🧪 Materials

Commercially pure aluminium (the 1xxx series, 99% Al or better) is a soft, ductile, silvery metal made by electrolytic smelting of alumina from bauxite. Engineers pick it when low weight, corrosion resistance and good conductivity matter more than strength, as in conductors, foil and chemical equipment.

PropertiesDensity approx. 2.7 g/cm3, melting point approx. 660 °C, electrical conductivity roughly 60% of copper, a self-healing oxide film, and low strength (annealed tensile strength typically under about 120 MPa).

ApplicationsOverhead conductors and busbars, packaging foil, heat-exchanger fins, cooking utensils, lighting reflectors, chemical storage tanks and food-processing equipment.

SafetyFine aluminium powder and grinding dust are flammable and can form explosive clouds, so ventilate and remove ignition sources. Molten aluminium explodes on contact with moisture, so preheat tools, moulds and scrap.

Aluminium alloys add elements such as copper, magnesium, silicon, zinc or manganese to lift strength well above the pure metal, and are sold as wrought series (2xxx to 7xxx) or as cast grades. Heat treatment can multiply strength, letting designers keep the light weight in loaded structures.

PropertiesDensity stays near 2.7-2.8 g/cm3, while tensile strength ranges from about 100 MPa in 3003 to roughly 570 MPa in 7075-T6; corrosion resistance and weldability vary widely between series.

ApplicationsAircraft skins and frames (2024, 7075), car wheels and engine blocks, bicycle frames, ship superstructures (5083), extruded window sections (6063) and general structural members.

SafetyMachining produces fine chips and dust that can ignite, particularly in magnesium-rich grades, so keep swarf cleared. Welding fumes need extraction, and 7xxx alloys can crack under stress if wrongly tempered.

Copper is a reddish, ductile metal usually supplied at 99.9% purity and refined electrolytically from sulphide ores. Its outstanding electrical and thermal conductivity makes it the default for wiring and heat transfer, and it also resists atmospheric and fresh-water corrosion.

PropertiesDensity approx. 8.96 g/cm3, melting point approx. 1085 °C, electrical conductivity 100% IACS (the reference standard), thermal conductivity approx. 390-400 W/m.K, and excellent ductility.

ApplicationsElectrical cables and windings, busbars, transformer and motor coils, printed-circuit traces, water and refrigerant tubing, heat exchangers and solar thermal collectors.

SafetyWelding or brazing copper gives fumes that can cause metal-fume fever, so use local exhaust. Because it conducts so well, isolate and lock out circuits before working on busbars, and expect hot tubes to burn.

Copper alloys are the family in which copper is the main element, combined with zinc (brass), tin (bronze), nickel (cupronickel), aluminium or beryllium. Alloying trades away some conductivity for strength, wear resistance, machinability or seawater resistance when pure copper is too soft.

PropertiesDensity about 7.5-9 g/cm3; tensile strength spans roughly 200 MPa in soft brass to above 1000 MPa in heat-treated beryllium copper, with good corrosion resistance and lower conductivity than pure copper.

ApplicationsValves and fittings, ship propellers and condenser tubes, bearings and bushes, electrical connectors and springs, coinage, musical instruments and architectural hardware.

SafetyBeryllium copper dust and fume are toxic and need strict controls, and free-cutting leaded alloys release lead when machined. Confirm the alloy composition and follow the supplier safety data sheet.

Brass is a copper-zinc alloy, typically 55-90% copper, sometimes with small additions of lead, tin or aluminium. It casts and machines cleanly and has a gold-like colour, which is why it is a common choice for fittings, fasteners and decorative parts.

PropertiesDensity approx. 8.4-8.7 g/cm3, melting range roughly 880-950 °C, tensile strength about 300-600 MPa depending on zinc content, with excellent machinability in free-cutting grades and fair corrosion resistance.

ApplicationsPlumbing fittings, valve bodies, taps, electrical terminals, cartridge cases, screws, locks, radiator cores and instruments such as trumpets.

SafetyZinc vaporises when brass is welded or melted, giving white fume that causes metal-fume fever, so extract it. Leaded free-cutting brass is restricted in drinking-water parts; use lead-free grades there.

Bronze is traditionally copper alloyed mainly with tin, often 5-12%, although aluminium, silicon and phosphorus bronzes also exist. It is harder and more wear-resistant than brass, handles seawater well and runs with low friction against steel, so it is favoured for bearings and marine parts.

PropertiesDensity approx. 8.7-8.9 g/cm3, melting range roughly 900-1050 °C, tensile strength approx. 250-700 MPa across grades, with good wear resistance, seawater corrosion resistance and low friction.

ApplicationsSleeve bearings and bushes, worm-wheel gears, ship propellers, pump impellers, bells, phosphor-bronze springs and statues.

SafetyMolten bronze spatters violently if moulds or scrap are damp, so preheat everything. Leaded bearing bronzes release lead dust and fume when melted or machined; use extraction and wash hands.

Mild steel is low-carbon steel with roughly 0.05-0.25% carbon and little alloying, rolled into plates, bars, angles and sheets. It is cheap, tough and easy to weld, bend and machine, making it the default structural and fabrication material in workshops.

PropertiesDensity approx. 7.85 g/cm3, melting point about 1425-1500 °C, tensile strength roughly 400-550 MPa, yield about 250 MPa in IS 2062 E250, rusts readily and does not harden much on quenching.

ApplicationsStructural beams and columns, machine frames, brackets, low-duty shafts, bolts, pipes, tanks, vehicle body panels and general fabrication work.

SafetyGas cutting and welding throw sparks and produce fume, so remove paint or galvanising first and ventilate. Cut edges are sharp, and bare surfaces rust, so paint or coat after fabrication.

Carbon steel is the broad class of iron-carbon steels whose properties are set mainly by carbon content rather than by deliberate alloying, split into low, medium and high carbon grades. It lets designers trade ductility and weldability against hardness and strength through a single element.

PropertiesDensity approx. 7.85 g/cm3; carbon ranges from about 0.05% to over 1%, with strength and hardness rising and ductility falling as carbon increases, and heat treatment becoming effective above about 0.3% C.

ApplicationsRails, wire, pressure vessels, forged crankshafts, gears, axles, knives, cutting tools, springs and reinforcement bars, depending on the carbon grade selected.

SafetyQuenching in oil or water brings fire and steam-splash risks, so guard the bath. Grinding and machining throw hot sparks and swarf; wear eye protection and keep oily scrap away from ignition.

Medium carbon steel contains about 0.30-0.60% carbon, usually with 0.6-1.65% manganese. It can be quenched and tempered to give a good balance of strength, toughness and wear resistance, as in IS C45 or AISI 1045 shafts and gears.

PropertiesDensity approx. 7.85 g/cm3; tensile strength roughly 570-700 MPa as rolled or normalised and above 800 MPa when quenched and tempered, with fair machinability and weldability that needs preheat.

ApplicationsCrankshafts, axles, connecting rods, gears, shafts, couplings, studs, rail wheels and forged machine parts that need strength with some toughness.

SafetyWelding without preheat can leave hard, crack-prone heat-affected zones. Quench cracking and flying fragments are risks in heat treatment, so use guards, the correct quenchant and face protection.

High carbon steel holds roughly 0.60-1.5% carbon, giving a hard, strong but less ductile metal once heat-treated. The martensitic hardness suits cutting edges and springs, while the high carbon makes welding and cold forming difficult.

PropertiesDensity approx. 7.85 g/cm3; tensile strength commonly 700-1000 MPa or more after heat treatment, quenched hardness up to approx. 60-65 HRC, low ductility, poor weldability and good wear resistance.

ApplicationsChisels, hammers, punches, files, saw blades, wire ropes, piano wire, railway rails and knives, wherever hardness and edge retention matter.

SafetyHardened pieces are brittle and can shatter when struck, so wear eye protection. Quenching and tempering involve hot oil and furnaces, and welding needs preheat and slow cooling to avoid cracking.

Alloy steel is steel deliberately alloyed with chromium, nickel, molybdenum, vanadium or similar elements, usually totalling up to about 5%. These additions deepen hardenability and improve toughness at section sizes where plain carbon steel through-hardens poorly.

PropertiesDensity approx. 7.85 g/cm3; quenched and tempered grades such as 4140 reach tensile strengths of roughly 900-1200 MPa, with good toughness and fatigue resistance but welding that needs careful control.

ApplicationsGears, crankshafts, axles, high-strength bolts, aircraft landing-gear parts, hydraulic shafts and oil-field tooling, in grades like 4140, 4340 and 8620.

SafetyMany alloy steels air-harden next to welds and need preheat and slow cooling to prevent cracks. Welding or flame-cutting chromium and nickel grades gives toxic fume, so extract it.

Stainless steel is iron alloyed with at least 10.5% chromium, which forms a thin self-healing oxide film. Austenitic 304 and 316, ferritic 430, martensitic 410 and 420 and duplex 2205 are the main families, selected by corrosion environment, strength and cost.

PropertiesDensity approx. 7.7-8.0 g/cm3; annealed 304 has tensile strength of at least about 515 MPa and is non-magnetic, duplex grades have roughly twice its yield strength, and pitting resistance rises with molybdenum.

ApplicationsKitchen sinks and cookware, food and dairy plant, chemical tanks, surgical instruments, pharmaceutical piping, architectural cladding, marine fittings and exhaust systems.

SafetyWelding and grinding release chromium and nickel fume, including hexavalent chromium, so use extraction and respiratory protection. Use dedicated stainless tools, since carbon-steel contamination causes rust spots.

Tool steels are high-hardness steels made with controlled carbon and alloying elements such as tungsten, molybdenum, vanadium and chromium. They hold an edge, resist wear and keep strength under heat or impact, so they are used to cut, form and shape other materials.

PropertiesDensity approx. 7.7-8.1 g/cm3; working hardness typically 55-67 HRC; grades include water-hardening (W), cold-work (O, A, D), shock-resisting (S), hot-work (H) and high-speed (M, T) types.

ApplicationsDrill bits, taps, milling cutters, punches and dies, forging and die-casting dies, plastic injection moulds, shear blades and knives.

SafetyHeat treatment uses salt baths and furnaces with burn and fume hazards. Fully hardened tool steel can chip sharply under impact, so wear eye protection and extract grinding dust from cobalt-bearing grades.

Spring steel covers medium-to-high carbon and low-alloy steels such as 1095, 5160, 9260 and chrome-vanadium grades, chosen for a high elastic limit. After quench and temper they return to shape after large deflections, which is exactly what springs require.

PropertiesDensity approx. 7.85 g/cm3; tensile strength commonly 1200-2000 MPa after heat treatment, high yield strength, good fatigue resistance and an elastic modulus of approx. 200 GPa.

ApplicationsLeaf springs, coil and valve springs, clips, circlips, saw blades, clock springs, thin shim stock, lock washers and vehicle suspension parts.

SafetyStored energy is the main hazard, since compressed springs can release suddenly and injure. Use spring compressors and eye protection, and avoid welding or overheating, which destroys the temper.

Bearing steel is a high-carbon chromium steel such as AISI 52100 (about 1% C and 1.5% Cr), melted extra clean to limit non-metallic inclusions. After through-hardening it resists rolling-contact fatigue, which is why ball and roller bearings use it.

PropertiesDensity approx. 7.8 g/cm3; hardened to approx. 58-65 HRC, with high wear resistance and rolling-contact fatigue life, but limited corrosion resistance and poor weldability.

ApplicationsBall and roller bearing races and rolling elements, precision spindles, ball screws, linear guides, needle rollers and gauge components.

SafetyHardened races are brittle and fracture if hammered, so fit them with presses or induction heaters. Heated bearings should generally stay below about 120 °C, and hot parts need gloves.

Cast iron is the family of iron alloys with more than about 2% carbon, typically 2.5-4%, plus silicon, poured into moulds. Free graphite or carbides in the structure give excellent castability, damping and wear resistance, but brittleness limits it to compression-loaded shapes.

PropertiesDensity approx. 6.9-7.4 g/cm3; melting range about 1150-1200 °C; high compressive strength, good damping and machinability, but low ductility and lower tensile strength than steel.

ApplicationsMachine tool beds, engine blocks, pump casings, pipes and fittings, brake drums and discs, manhole covers, flywheels and cookware.

SafetyMachining produces fine abrasive dust, so extract it. Molten iron with damp moulds or scrap is an explosion and burn hazard, and large castings need proper lifting gear.

Grey cast iron holds its carbon as flake graphite, which gives fractured surfaces a grey colour. The flakes damp vibration, conduct heat well and make machining easy, but they also act as crack starters, so tensile strength and ductility stay low.

PropertiesDensity approx. 7.1-7.3 g/cm3; tensile strength about 150-400 MPa (IS 210 grades FG 150 to FG 400); compressive strength several times higher; excellent damping and machinability; almost no ductility.

ApplicationsLathe and milling machine beds, engine cylinder blocks and liners, brake discs and drums, gearbox housings, pump bodies and flywheels.

SafetyBrittle material that shatters if dropped or struck, so wear safety shoes when handling castings. Dry machining raises graphite and iron dust that irritates the lungs; extract it.

Ductile iron, also called spheroidal graphite (SG) or nodular iron, is made by treating molten iron with magnesium or cerium so the graphite forms spheres instead of flakes. This removes the crack-starting effect and gives steel-like strength and elongation with good castability.

PropertiesDensity approx. 7.1 g/cm3; tensile strength about 400-800 MPa and elongation roughly 2-18% depending on grade (for example SG 400/15 and SG 500/7); good fatigue strength and wear resistance.

ApplicationsWater and sewage pipes, crankshafts, gears, suspension knuckles, hydraulic housings, wind-turbine hubs and heavy-duty pipe fittings.

SafetyMagnesium treatment causes intense flare, fume and splashing, so foundries need shields and protective clothing. Extract machining dust, and use correct lifting equipment for heavy castings.

Malleable iron starts as white cast iron, which is then annealed for many hours so the hard carbide breaks down into temper-carbon nodules. The result is a tough, shock-resistant casting in thin sections, though ductile iron has replaced it in many larger parts.

PropertiesDensity approx. 7.2-7.4 g/cm3; tensile strength typically 300-700 MPa; good ductility, shock resistance and machinability, but section thickness is limited because castings must first solidify as white iron.

ApplicationsPipe fittings, hand-tool bodies, brackets, hinges, chain links, small gear housings, agricultural and railway fittings and electrical line hardware.

SafetyAnnealing furnaces run above about 900 °C, so burns and furnace-atmosphere hazards apply. Machining dust should be extracted, and thin sections can still crack if cold-hammered.

Wrought iron is nearly carbon-free iron, under about 0.1% C, containing fibrous slag stringers, historically produced by puddling and hammering. It is soft, tough and forge-welds easily; modern production has virtually ceased and mild steel is the usual substitute.

PropertiesDensity approx. 7.7-7.8 g/cm3; tensile strength roughly 250-350 MPa; very low carbon, a fibrous grain with good forge-welding and corrosion resistance, but low strength compared with steel.

ApplicationsTraditional gates, railings, anchors, chains and hooks, and restoration of historic bridges and buildings; new ornamental ironwork is usually mild steel.

SafetyHot forging brings burns and flying scale. Old wrought ironwork may carry lead-based paint, so test it before sanding or flame-cutting restoration items.

Commercially pure titanium (ASTM grades 1-4) is a silvery metal with a stable oxide film, extracted from rutile or ilmenite by the Kroll process. Grades differ mainly in oxygen content, and it offers outstanding seawater and chloride resistance at a high cost.

PropertiesDensity approx. 4.5 g/cm3, melting point approx. 1668 °C, tensile strength approx. 240-550 MPa from grade 1 to grade 4, low thermal expansion, non-magnetic, and excellent resistance to seawater.

ApplicationsChemical-plant heat exchangers, desalination and marine condensers, medical and dental implants, surgical tools and pharmaceutical equipment.

SafetyTitanium chips, fines and dust are flammable and burn intensely, so use sharp tools, plenty of coolant and Class D extinguishers. Welding needs full inert-gas shielding.

Titanium alloys, led by Ti-6Al-4V (grade 5), add aluminium, vanadium and other elements to raise strength far above pure titanium. They are classed as alpha, alpha-beta or beta and are chosen where strength-to-weight and heat resistance justify the cost.

PropertiesDensity approx. 4.4-4.8 g/cm3; annealed Ti-6Al-4V has tensile strength of roughly 900-1100 MPa and serves to about 400 °C, with high specific strength and fatigue resistance.

ApplicationsJet-engine compressor blades, airframe fittings, landing gear, orthopaedic implants, racing-engine valves, bicycle frames and offshore risers.

SafetyMachining throws sparks and flammable swarf, and fine powder can be pyrophoric, so avoid dry cutting. Hot work leaves a brittle oxygen-rich layer, so weld under inert gas.

Nickel is a silvery, ferromagnetic metal supplied as 99%+ pure rod, sheet, wire and anodes, produced mostly from sulphide and laterite ores. It resists caustic alkalis and many chemicals, holds up at heat, and underpins plating and alloy production.

PropertiesDensity approx. 8.9 g/cm3, melting point approx. 1455 °C, ferromagnetic below a Curie point of about 358 °C, good ductility and excellent resistance to caustic alkalis.

ApplicationsElectroplating and electroforming, battery electrodes (NiCd, NiMH), caustic-soda process equipment, coinage cladding, heating elements and alloy production for stainless steel.

SafetyNickel is a common skin sensitiser causing contact dermatitis, and inhaling nickel dust or compounds is a recognised cancer hazard. Wear gloves, control dust and fume, and follow the SDS limits.

Nickel alloys form a wide group in which nickel is the main element, combined with chromium, copper, iron, molybdenum or cobalt. Inconel, Monel, Hastelloy and Nimonic are examples, selected for oxidation, creep or acid resistance beyond what stainless steel offers.

PropertiesDensity approx. 8.2-9.0 g/cm3; many retain useful strength to roughly 700-1000 °C depending on alloy, resist oxidation, acids and stress corrosion, but work-harden strongly and cost more.

ApplicationsGas-turbine and jet-engine parts, chemical reactors, nuclear steam-generator tubes, furnace fixtures, sour-service oil and gas valves and Ni-Cr heater wire.

SafetyWork-hardening makes machining difficult, with hot chips and tool breakage, so use rigid setups and coolant. Welding and grinding fumes contain nickel and chromium and need extraction.

Inconel is the Special Metals trade name for a family of austenitic nickel-chromium superalloys, including 600, 625 and 718. Their chromium, molybdenum or niobium content resists oxidation and keeps strength at temperatures where steels soften.

PropertiesDensity approx. 8.2-8.5 g/cm3; melting range roughly 1260-1430 °C; aged Inconel 718 exceeds about 1200 MPa tensile strength, and the family resists oxidation and creep up to around 700 °C.

ApplicationsTurbine blades and discs, exhaust systems, rocket-engine parts, furnace muffles, nuclear reactor components, chemical process pipework and heat-treatment baskets.

SafetyStrong work-hardening produces tough, hot chips, so use sharp carbide tools and coolant. Welding fume contains nickel, chromium and niobium compounds; extract it and wear a respirator as the SDS directs.

Monel is the trade name for nickel-copper alloys of roughly 63-67% nickel and 28-34% copper, notably Monel 400 and the age-hardening K-500. It is outstanding in seawater, hydrofluoric acid and alkalis and is fabricated much like stainless steel.

PropertiesDensity approx. 8.8 g/cm3; melting range about 1300-1350 °C; Monel 400 tensile strength roughly 480-620 MPa; excellent seawater and HF resistance, while K-500 can be precipitation-hardened.

ApplicationsMarine pump and propeller shafts, valve trim, seawater piping, heat exchangers, hydrofluoric-acid process equipment and refinery equipment.

SafetyIt work-hardens, so avoid light rubbing cuts when machining. Welding and grinding fumes contain nickel and copper and need extraction, and pickling acids used in fabrication call for care.

Chromium is a hard, brittle, silvery-white metal obtained from chromite ore. In bulk it is rarely a structural metal; instead it is chiefly added to steel to make it stainless, or electroplated as a bright, hard, corrosion-resistant layer.

PropertiesDensity approx. 7.15 g/cm3, melting point approx. 1907 °C, very hard (hard-chrome plating about 800-1000 HV), brittle at room temperature, and forms a passive oxide film that resists tarnish.

ApplicationsStainless and alloy steel production, decorative and hard chrome plating of hydraulic rods and rolls, nichrome heating wire, refractory bricks and chrome pigments.

SafetyHexavalent chromium in plating baths and in stainless-steel welding fume is toxic and carcinogenic; use extraction, protective gear and controlled waste handling. The bulk metal is far less hazardous.

Zinc is a bluish-white metal produced from sphalerite ore, relatively soft and brittle at room temperature. Its main engineering role is sacrificial corrosion protection as galvanising on steel, with further use in die casting and brass making.

PropertiesDensity approx. 7.14 g/cm3, melting point approx. 420 °C, low hardness, anodic to iron so it corrodes first, brittle near room temperature but malleable at about 100-150 °C.

ApplicationsHot-dip galvanising of sheet, sections and fasteners, sacrificial anodes for ship hulls, dry-cell battery cans, brass production and roofing sheet.

SafetyFume from welding galvanised steel or from molten zinc causes metal-fume fever, so use extraction. Molten zinc spits violently on contact with damp tools, and zinc dust is flammable.

Zinc alloys combine zinc with aluminium, copper and magnesium, notably the Zamak 3 and 5 and the ZA-8, ZA-12 and ZA-27 families. Their low melting point suits high-volume die casting of thin-wall, detailed parts with good dimensional accuracy.

PropertiesZamak density approx. 6.6 g/cm3, melting range about 380-390 °C, tensile strength approx. 280-330 MPa, with excellent castability and surface finish but poor creep resistance at elevated temperature.

ApplicationsDie-cast door handles, locks, zip fasteners, toy cars, carburettor bodies, plumbing fixtures, small gears and electrical connector housings.

SafetyLead, tin or cadmium contamination causes intergranular corrosion and cracking, so keep scrap segregated. Die-casting machines present molten metal, splash and fume risks; never add damp scrap.

Magnesium is the lightest structural metal, produced from magnesite, brine or seawater by electrolysis or the Pidgeon process. Unalloyed magnesium is weak and rarely used structurally, but it matters as an alloying element, reducing agent and sacrificial anode.

PropertiesDensity approx. 1.74 g/cm3, melting point approx. 650 °C, hexagonal crystal structure with limited room-temperature formability, low unalloyed strength, and strongly anodic corrosion behaviour.

ApplicationsSacrificial anodes for pipelines and water heaters, alloying additive in aluminium, steel desulphurisation, flares and flash powder.

SafetyMagnesium burns with intense white light, and water makes the fire worse. Fine ribbon, powder and swarf are fire hazards, so use Class D agent or dry sand and never stare at the flame.

Magnesium alloys such as cast AZ91 and wrought AZ31 add aluminium, zinc, manganese or rare earths to magnesium. They offer the lowest density of any structural metal with excellent machinability and damping, which suits lightweight housings.

PropertiesDensity approx. 1.74-1.85 g/cm3; tensile strength typically 160-350 MPa; high specific strength, excellent machinability and damping, but poor corrosion and creep resistance and limited cold formability.

ApplicationsLaptop and camera bodies, gearbox casings, steering-wheel and seat frames, aerospace housings, power-tool bodies and wheel rims.

SafetyThin chips and fine dust ignite easily and burn fiercely, so keep swarf cleared and water away from fires. Steel contact promotes galvanic corrosion, so isolate fasteners.

Lead is a dense, soft, grey metal obtained mainly from galena. It is easy to cast and work, resists many acids, and its high density gives excellent radiation shielding, although toxicity has reduced its use in many products.

PropertiesDensity approx. 11.34 g/cm3, melting point approx. 327 °C, very soft and ductile, resistant to sulphuric acid, strongly attenuates X-rays and gamma rays, and creeps at room temperature.

ApplicationsLead-acid battery plates, X-ray and nuclear radiation shielding, cable sheathing in older cables, ballast weights, acid-resistant linings and exempt solder applications.

SafetyToxic by ingestion and by inhaling dust or fume, with cumulative effects, so never eat, drink or smoke near it. Avoid dry sanding, wash hands, and follow local lead exposure and disposal rules.

Tin is a soft, silvery, corrosion-resistant metal produced from cassiterite. It is seldom used alone as structure but is valued for coating steel as tinplate, forming solder and bronze, and as a low-toxicity alloying metal.

PropertiesDensity approx. 7.3 g/cm3, melting point approx. 232 °C, very soft and ductile, non-toxic and corrosion-resistant, and can suffer tin pest, a change to brittle grey tin, after long exposure to deep cold.

ApplicationsTinplate food cans, lead-free solders, bronze and pewter production, bearing alloys such as babbitt, tin-coated copper wire and float-glass bath.

SafetyMetallic tin has low toxicity, but soldering flux fume irritates the respiratory tract, so extract it. Molten tin causes severe burns, and flux residue should be cleaned from electronics.

Cobalt is a hard, blue-silvery ferromagnetic metal obtained mostly as a by-product of nickel and copper mining. It goes chiefly into superalloys, hard-facing alloys, magnets and lithium-ion battery cathodes, where it keeps strength and magnetism at high temperature.

PropertiesDensity approx. 8.9 g/cm3, melting point approx. 1495 °C, ferromagnetic with a Curie temperature near 1115 °C, hard, wear-resistant, and retains strength at high temperature.

ApplicationsLithium-ion battery cathodes, jet-engine superalloys, permanent magnets (alnico, samarium-cobalt), cemented-carbide binder, catalysts, blue pigments and Co-60 radiotherapy sources.

SafetyCobalt dust and fume can sensitise skin and lungs and are suspected carcinogens, so control dust and wear gloves. Radioactive Co-60 sources require licensed handling and shielding.

Cobalt alloys include cobalt-chromium-tungsten Stellite wear alloys, cobalt-chromium-molybdenum (CoCrMo) biomedical alloys and cobalt-based superalloys such as Haynes 25. They resist wear, galling, corrosion and heat where severe service would soften steel, and are chosen for valve seats, implants and hard-facing despite difficult machining.

PropertiesDensity approx. 8.3-9.0 g/cm3; Stellite 6 hardness is roughly 40 HRC as deposited; many grades keep strength to approx. 800-1000 °C, with excellent galling, wear and corrosion resistance.

ApplicationsEngine valve seats and hard-facing, hip and knee implants, dental prostheses, cutting-tool edges, turbine vanes and pump wear rings.

SafetyMachining and grinding create cobalt- and chromium-bearing dust that can sensitise skin and lungs; use extraction and gloves. Hard-facing weld fume needs local exhaust and respiratory protection.

Tungsten is a dense grey-white metal with the highest melting point of any metal, obtained from wolframite and scheelite. Because it cannot be melted conveniently, it is shaped by powder metallurgy and sintering, and it underlies carbide tools and filaments.

PropertiesDensity approx. 19.3 g/cm3, melting point approx. 3422 °C, very high stiffness and hardness, low thermal expansion, strength retained at high temperature, and brittle at room temperature unless worked.

ApplicationsLamp filaments, TIG welding electrodes, X-ray anodes, heavy counterweights, rocket nozzles and as the base of tungsten carbide cutting tools.

SafetyPure tungsten is of low toxicity, but fine powder irritates lungs. Grinding thoriated TIG electrodes produces weakly radioactive dust, so prefer lanthanated or ceriated types and extract dust.

Molybdenum is a silvery-grey refractory metal produced mainly from molybdenite and as a by-product of copper mining. Mostly used to alloy steels, it also serves alone in high-temperature furnace parts thanks to its high melting point and good thermal conductivity.

PropertiesDensity approx. 10.2 g/cm3, melting point approx. 2623 °C, high stiffness (modulus approx. 330 GPa), low thermal expansion and good conductivity, but it oxidises rapidly in air above about 600 °C.

ApplicationsAlloying in stainless and high-strength steels, furnace heating elements and hot zones, glass-melting electrodes, X-ray targets and molybdenum disulphide lubricant.

SafetyThe metal has low toxicity, but dust and molybdenum trioxide fume from hot oxidation irritate the lungs, so use extraction. Hot parts need vacuum or hydrogen furnaces to avoid rapid oxidation.

Vanadium is a hard, silvery-grey metal obtained from vanadium-bearing magnetite slag and ores. It is rarely used pure; nearly all goes into steel as small additions that refine grain and form hard carbides, and into titanium alloys and redox batteries.

PropertiesDensity approx. 6.1 g/cm3, melting point approx. 1910 °C, ductile when pure, forms hard stable carbides in steel, and its oxide film resists many acids and alkalis.

ApplicationsHigh-speed and tool steels, spring and HSLA steels, Ti-6Al-4V alloy, vanadium redox flow batteries and V2O5 catalyst for sulphuric acid production.

SafetyVanadium pentoxide dust and fume are toxic and irritate the eyes and lungs, with possible long-term effects, so use extraction and a respirator and follow the SDS exposure limits.

The most widely produced thermoplastic, made by polymerising ethylene into a semi-crystalline, waxy-feeling polymer. It is tough, chemically inert and easy to extrude, blow-mould or rotomould, so engineers use it where low cost, moisture resistance and electrical insulation matter more than stiffness or heat resistance.

PropertiesDensity approx. 0.91-0.96 g/cm3 depending on branching; melts at approx. 105-135 °C; low moisture absorption, excellent chemical and electrical insulation properties, but low stiffness and poor UV resistance unless stabilised.

ApplicationsWater and gas pipes, cable insulation, packaging films, tanks, bottles, chemical-resistant liners, and food containers across agriculture, utilities and consumer goods.

SafetyBurns readily with a dripping flame, so keep away from ignition sources and hot work. Molten polymer causes severe burns; extrusion fumes from overheating need local ventilation.

A mostly linear form of polyethylene with little chain branching, giving higher crystallinity than LDPE. That makes it stiffer, stronger and more heat tolerant, which is why it is preferred for pressure pipes, rigid containers and fuel or chemical tanks.

PropertiesDensity approx. 0.94-0.97 g/cm3; melting point approx. 130 °C; tensile strength approx. 20-37 MPa; good chemical and impact resistance, but notch sensitive and prone to stress cracking.

ApplicationsWater and gas distribution pipes, jerrycans, fuel tanks, geomembranes, crates, milk and detergent bottles, and wear liners for chutes and hoppers.

SafetyFlammable and drips when burning; do not butt-fuse pipes with damaged heater plates or without cooling time. Hot fusion tools cause burns and welding fumes should be ventilated.

A highly branched polyethylene made by high-pressure polymerisation, which keeps chains from packing tightly. The result is a soft, flexible, transparent-to-translucent material with excellent toughness at low temperature, chosen for films, coatings and flexible tubing rather than load-bearing parts.

PropertiesDensity approx. 0.91-0.93 g/cm3; melts at approx. 105-115 °C; tensile strength approx. 8-20 MPa; very flexible, low moisture absorption and good chemical resistance.

ApplicationsShrink and stretch films, carrier bags, squeeze bottles, wire and cable sheathing, extrusion coatings on paperboard, and flexible tubing for water or laboratory use.

SafetyLow melting point means parts soften near hot surfaces, so keep clear of heaters and steam lines. Burns with a drip; hot extrusion melt and fumes need ventilation and heat-resistant gloves.

A lightweight semi-crystalline thermoplastic made from propylene. It has a higher melting point and stiffness than polyethylene and an excellent fatigue life, which allows thin-section living hinges, so it is used for automotive parts, containers and fibres.

PropertiesDensity approx. 0.90-0.91 g/cm3, the lowest of the common plastics; homopolymer melts at approx. 160-170 °C; tensile strength approx. 25-40 MPa; good chemical resistance but brittle in cold and degraded by UV.

ApplicationsCar bumpers and battery cases, appliance housings, chemical-resistant tanks and pipes, bottle caps with integral hinges, woven sacks, ropes and nonwoven medical fabrics.

SafetyFlammable and burns with dripping molten plastic. Avoid prolonged sunlight exposure for unstabilised parts, and ventilate during hot welding or moulding where degradation vapours form.

A chlorine-containing thermoplastic produced in rigid (uPVC) and plasticised flexible forms. Its low cost, flame-retarding chlorine content and good corrosion resistance make it the default material for water pipes, conduit and window profiles in construction.

PropertiesRigid grades have density approx. 1.3-1.45 g/cm3 and tensile strength approx. 40-60 MPa; maximum service temperature only approx. 60 °C; self-extinguishing, with good chemical and weather resistance.

ApplicationsDrainage and water pipes, electrical conduit, window frames, cable insulation and sheathing, flooring, tubing, and chemical process piping at modest temperatures.

SafetyOverheating or burning releases corrosive hydrogen chloride gas, so avoid hot work near it and never overheat in processing. Solvent cement fumes are flammable; ventilate and follow the data sheet.

Made by post-chlorinating PVC resin, which raises its chlorine content and so its heat deflection temperature. Compared with ordinary PVC, it handles hot water and hotter corrosive fluids while keeping similar ease of solvent-cement jointing.

PropertiesDensity approx. 1.5 g/cm3; service up to roughly 90-95 °C for pressure piping, well above standard PVC; excellent resistance to acids, salts and chlorinated water; inherently flame retardant.

ApplicationsHot and cold potable water plumbing, fire sprinkler systems, industrial chemical process pipes, and hot-acid or bleach handling lines in plating and water treatment plants.

SafetySolvent cements are flammable and give off irritating vapours, so ventilate and avoid ignition sources. Burning or overheating releases hydrogen chloride; keep pipe away from heat tracing beyond its rating.

A clear, rigid, amorphous thermoplastic made by polymerising styrene. General-purpose grade is stiff and cheap but brittle, while high-impact (HIPS) adds rubber for toughness; expanded PS foam serves as a lightweight insulating and packaging material in many industries.

PropertiesSolid density approx. 1.04-1.05 g/cm3; glass transition near 100 °C; tensile strength approx. 35-55 MPa; brittle, easy to mould, poor resistance to solvents, oils and UV.

ApplicationsDisposable cups and cutlery, CD cases, appliance housings, laboratory ware, model kits, and expanded foam for packaging and building insulation boards.

SafetyHighly flammable, burning with heavy black smoke and styrene vapour. Keep away from hot work and solvents such as acetone, which dissolve and craze it; ventilate when hot-wire cutting foam.

A terpolymer of acrylonitrile, butadiene and styrene in which rubbery butadiene particles toughen a rigid styrene-acrylonitrile matrix. It balances impact strength, stiffness and surface finish, and it machines, glues and plates well, which is why it is a staple for housings and 3D printing.

PropertiesDensity approx. 1.04-1.06 g/cm3; tensile strength approx. 40-50 MPa; glass transition near 105 °C; tough at low temperature but with limited UV and solvent resistance unless protected.

ApplicationsInstrument and appliance housings, automotive trim, pipes and fittings, LEGO-type bricks, helmets, luggage shells, and fused-filament 3D printing parts.

SafetyFlammable and emits styrene and acrylonitrile vapours when overheated or burned. Use fume extraction while 3D printing or hot cutting, and keep melt temperatures within the supplier range.

The common name for aliphatic polyamides, mainly PA6 and PA66, made by polymerising lactams or diacid and diamine. Their hydrogen-bonded chains give high toughness, fatigue life and wear resistance, but they absorb moisture, which changes dimensions and properties.

PropertiesDensity approx. 1.13-1.15 g/cm3; melting point approx. 220 °C (PA6) to 260 °C (PA66); dry tensile strength approx. 60-80 MPa; absorbs approx. 2-3% moisture at room humidity, lowering stiffness.

ApplicationsGears, bushes, bearing cages, cable ties, fasteners, rollers, automotive under-bonnet parts, fishing line, textiles, and glass-filled structural components.

SafetyDry resin before moulding because moisture causes defects and hydrolysis. Hot melt causes burns; overheating produces irritating fumes, and glass-filled grades give abrasive dust when machined.

A transparent amorphous thermoplastic based on bisphenol A carbonate linkages. It is valued for extraordinary impact strength combined with optical clarity and dimensional stability, making it the standard choice wherever glass would shatter or break under shock loading.

PropertiesDensity approx. 1.20 g/cm3; glass transition near 147 °C; tensile strength approx. 55-70 MPa; light transmission approx. 88%; very high impact strength but poor scratch and chemical stress-crack resistance.

ApplicationsMachine guards and safety visors, helmets, headlamp lenses, optical discs, roofing sheets, electrical housings, and transparent enclosures for instruments.

SafetyMust be dried before moulding; avoid contact with solvents, fuel and some cleaning agents that cause stress cracking. Burns slowly; hot processing needs ventilation, and cut edges can be sharp.

Polytetrafluoroethylene, a fully fluorinated polymer whose strong carbon-fluorine bonds make it almost chemically inert. It cannot be melt-processed normally, so it is sintered or paste-extruded, and it offers the lowest friction of any common solid.

PropertiesDensity approx. 2.1-2.3 g/cm3; melting point approx. 327 °C with service up to about 260 °C; friction coefficient approx. 0.05-0.1; inert to nearly all chemicals but soft and prone to creep.

ApplicationsChemical-resistant seals and gaskets, lined pipes and valves, bearing pads, wire insulation, non-stick coatings, thread sealing tape, and laboratory ware.

SafetyHeating above about 300 °C releases toxic fumes that can cause polymer fume fever, so avoid smoking or welding near it. Do not machine or sinter without ventilation.

Polyether ether ketone, a high-performance semi-crystalline thermoplastic with an aromatic backbone. It retains strength at high temperature and resists hot water, steam and many chemicals, so it replaces metals in demanding, lightweight components where weight and corrosion matter.

PropertiesDensity approx. 1.30-1.32 g/cm3; melts near 343 °C with continuous service approx. 250 °C; tensile strength approx. 90-100 MPa unfilled; excellent wear, hydrolysis and chemical resistance.

ApplicationsAerospace brackets, oil and gas seals and back-up rings, semiconductor wafer handling parts, spinal implants, pump wear rings, and high-temperature bearings.

SafetyProcessing needs high barrel and mould temperatures around 380-400 °C, so burn hazards are significant. Avoid overheating that releases fumes; machining chips and carbon-filled dust need extraction.

Polyoxymethylene, sold as acetal, is a dense semi-crystalline polymer made in homopolymer (Delrin type) and copolymer forms. It is stiff, dimensionally stable, slippery and machines cleanly, making it a favourite for precision moving parts in machinery.

PropertiesDensity approx. 1.41-1.42 g/cm3; melts approx. 165 °C (copolymer) to 175 °C (homopolymer); tensile strength approx. 60-70 MPa; low friction, low moisture uptake, creep resistant, poor UV and strong-acid resistance.

ApplicationsPrecision gears, cams, bearings, conveyor chain links, fuel system parts, zip fasteners, pump impellers, and valve components.

SafetyOverheating above about 230 °C decomposes it, releasing formaldehyde, an irritant and suspected carcinogen. Keep it out of PVC-contaminated processing equipment and ventilate when machining or moulding.

Polymethyl methacrylate is a rigid, transparent thermoplastic produced as cast or extruded sheet, rod and moulding granules. It has glass-like clarity and good weathering, with far lower weight than glass, but it is more brittle than polycarbonate.

PropertiesDensity approx. 1.18 g/cm3; light transmission approx. 92%; tensile strength approx. 50-75 MPa; glass transition near 105 °C; excellent weathering but scratches easily and is attacked by many solvents.

ApplicationsAquarium and display windows, sign letters, light guides and lenses, vehicle tail lamps, skylights, machine guards, and bone cement in orthopaedics.

SafetyBurns readily and drips. Laser cutting and hot work produce methyl methacrylate vapour, so extract fumes; bonding solvents are flammable, and sheet can crack from stress if cemented without annealing.

A polymer formed by reacting polyols with isocyanates, giving materials ranging from soft foam to hard cast elastomers. Cast PU bridges rubber and plastic, offering excellent abrasion and tear resistance with adjustable hardness for wheels, seals and linings.

PropertiesSolid elastomer density approx. 1.1-1.25 g/cm3; hardness adjustable from soft Shore A grades to hard Shore D; outstanding abrasion and cut resistance; limited hot-water and strong-acid resistance, with max service roughly 80-100 °C.

ApplicationsConveyor and screen wheels, rollers, seals and wipers, hydraulic cylinder seals, mining screens, shoe soles, foam insulation, coatings, and cushioning.

SafetyUncured isocyanates are respiratory sensitisers, so spray or cast only with ventilation and approved respiratory protection. Burning foam releases toxic gases including hydrogen cyanide; keep away from hot work.

Polyethylene terephthalate is a thermoplastic polyester produced by condensing terephthalic acid with ethylene glycol. It can be made clear and oriented for bottles and films or crystallised and glass-filled for engineering parts, with good barrier properties and strength-to-weight.

PropertiesDensity approx. 1.33-1.38 g/cm3; glass transition about 70-80 °C and melting point approx. 250-260 °C; tensile strength approx. 55-75 MPa; low moisture absorption and good gas barrier.

ApplicationsBeverage bottles, food trays, polyester textile fibres, magnetic tape and insulating films, gears and rollers in the engineering (PET-P) form, and 3D printing filament.

SafetyPellets must be dried thoroughly before melting to avoid hydrolysis. Molten polymer burns skin, and burning emits dense smoke; ventilate when hot-forming or welding recycled material.

Polybutylene terephthalate is a semi-crystalline thermoplastic polyester made from terephthalic acid and 1,4-butanediol. Unlike PET it crystallises quickly, so it moulds fast at low mould temperatures, and it is a mainstay for glass-filled electrical parts.

PropertiesDensity approx. 1.30-1.31 g/cm3; melting point approx. 223-225 °C; unfilled tensile strength approx. 50-60 MPa; very low moisture absorption, good electrical insulation and dimensional stability.

ApplicationsAutomotive connectors and sensor housings, relay and switch parts, appliance components, fuse boxes, gear housings and ignition coil bobbins.

SafetyDry before moulding to prevent hydrolysis. Flame-retarded grades may release halogenated fumes if overheated or burned; wear heat protection and ventilate near melt, and avoid dust from glass-filled grades.

A thermosetting polymer formed when epoxide-bearing resin is cured with a hardener such as an amine or anhydride. It cures with little shrinkage and bonds strongly to metals, glass and composites, which is why it is used for adhesives, coatings and composite matrices.

PropertiesCured density approx. 1.1-1.4 g/cm3; tensile strength approx. 50-90 MPa; glass transition anywhere from about 60 °C to over 200 °C depending on hardener; excellent adhesion, low shrinkage and chemical resistance.

ApplicationsStructural adhesives, printed circuit board laminates, potting of electronics, floor coatings, tooling, composite matrices for aircraft and wind blades, and anchoring bolts.

SafetyResins and amine hardeners cause skin sensitisation and dermatitis; wear nitrile gloves and avoid vapour. Large mixed batches generate exothermic heat, and sanding cured epoxy produces irritating dust.

A thermoset made by reacting phenol with formaldehyde, the original Bakelite chemistry. It forms a rigid, heavily cross-linked network that resists heat, flame and electricity, and is used with paper, cloth or wood flour fillers.

PropertiesUnfilled density approx. 1.25-1.4 g/cm3; useful continuously to roughly 150-200 °C; good electrical insulation, hardness and flame resistance, but brittle with a dark colour.

ApplicationsBrake linings and clutch facings, electrical switchgear parts, laminate boards (paper or cotton fabric), foundry core binders, pan handles, and grinding wheel bonding.

SafetyResidual phenol and formaldehyde can be released during curing, heating or machining, so ventilate and avoid skin contact. Fine dust from machining laminates should be extracted.

Melamine-formaldehyde is a hard thermosetting resin made from melamine and formaldehyde. Its scratch-resistant, heat-tolerant, stain-resistant surface can be cured under pressure as decorative laminate overlays and moulded tableware, and it is a common hard-wearing furniture surface in homes and offices.

PropertiesDensity approx. 1.5 g/cm3; very hard surface, scratch resistant and heat resistant relative to most plastics, good electrical arc resistance, and does not melt but chars at high temperature.

ApplicationsDecorative laminate surfaces for furniture and counters, moulded dinnerware, electrical insulating parts, surface coatings, and as a binder in wood panels.

SafetyFormaldehyde can be released from uncured or poorly cured products, so ventilate during pressing and curing. Sanding laminates produces fine dust; avoid overheating moulded ware, which can degrade.

A group of polysiloxane polymers whose backbone is silicon and oxygen rather than carbon, available as fluids, greases, rubbers and resins. Their stable backbone gives them a very wide temperature range and good dielectric behaviour.

PropertiesElastomer service range approx. -55 °C to 200-230 °C; density approx. 1.1-1.5 g/cm3; low compression set, excellent weathering and electrical insulation, but modest tear and tensile strength.

ApplicationsGaskets and O-rings, cable insulation, high-temperature hoses, sealants and adhesives, mould-making rubber, medical tubing, electronic potting and lubricant fluids.

SafetyAcetoxy-cure sealants release acetic acid vapour while curing, so ventilate. Burning leaves fine silica dust, and silicone oils contaminate surfaces and spoil painting or bonding nearby.

The broad polymer family with amide linkages in the chain, wider than everyday nylons. It includes aliphatic grades like PA6, PA66, PA11 and PA12, and aromatic polyamides (aramids). Choose it by grade according to stiffness, moisture absorption and heat requirements.

PropertiesAliphatic grades have density approx. 1.0-1.15 g/cm3 and melting points approx. 180-260 °C; they combine toughness and wear resistance, with moisture uptake falling from PA6 and PA66 to the long-chain PA11 and PA12.

ApplicationsFuel and brake lines (PA11/PA12), powder-bed 3D printing (PA12), textile fibres, engine covers, electrical connectors, and flame-resistant aramid fabrics.

SafetyDry before processing since moisture degrades the melt. Powder-bed polyamide dust is combustible, so control ignition sources and housekeeping; hot melt and thermal decomposition fumes call for ventilation.

A broad family of polymers joined by ester linkages. In engineering, it mostly means unsaturated polyester resin, a thermoset cured with styrene and a peroxide catalyst as the standard matrix for fibreglass laminates; thermoplastic polyesters appear separately as PET and PBT.

PropertiesCured resin density approx. 1.1-1.25 g/cm3; tensile strength approx. 40-70 MPa unreinforced; good water and weather resistance, moderate cost, but notable cure shrinkage and lower adhesion than epoxy.

ApplicationsBoat hulls, storage tanks, pipes, cladding panels and bath units in fibreglass, polymer concrete, cast buttons and polyester fabric.

SafetyStyrene vapour from open moulding is flammable and irritating, so use extraction and respirators. Organic peroxide catalysts (MEKP) are corrosive and can ignite if mixed directly with accelerators.

Polymers of acrylic and methacrylic acids and their esters, found as emulsions, solutions and cross-linked resins. In industry this mostly means acrylic binders in paints, adhesives and sealants, while the rigid sheet form is PMMA.

PropertiesProperties vary widely by monomer, but typical acrylics have excellent UV and weather stability, good clarity, strong adhesion to many substrates, and glass transition temperatures tunable from below zero to over 100 °C.

ApplicationsExterior paints and coatings, pressure-sensitive adhesives, construction sealants, textile finishes, leather and paper coatings, and superabsorbent polymers.

SafetyUncured acrylate monomers are skin and respiratory sensitisers with strong odour and flammable vapour. Wear gloves, ventilate during mixing and spraying, and check the supplier safety data sheet.

Natural rubber is cis-1,4-polyisoprene obtained from Hevea brasiliensis latex and then vulcanised with sulphur. It offers the best combination of resilience, tear strength and low heat build-up among general-purpose rubbers, but is weak against oils, ozone and sunlight.

PropertiesDensity approx. 0.92-0.95 g/cm3, elongation commonly 500-700%, gum tensile strength often above 20 MPa, service roughly -50 to 80 °C, with high resilience and poor oil, ozone and weather resistance.

ApplicationsTyre treads and truck tyres, anti-vibration engine mounts, bridge bearings, rubber bushes, conveyor belt covers, hoses and surgical gloves.

SafetyLatex proteins cause allergic reactions in some people, so offer non-latex gloves. Rubber is flammable, and ozone, sunlight and oils degrade it, so store parts cool, dark and clean.

SBR (styrene-butadiene rubber) is a synthetic copolymer, typically about 23% styrene, and is the highest-volume general-purpose synthetic rubber. It is cheaper than natural rubber and wears well once reinforced with carbon black, though it is weak in oil and ozone.

PropertiesDensity approx. 0.94 g/cm3, service roughly -40 to 100 °C, good abrasion resistance after filler reinforcement, moderate tensile strength, and poor resistance to oils, ozone and weathering.

ApplicationsPassenger-car tyre treads, conveyor belts, shoe soles, floor mats, general hoses, gaskets and cable insulation.

SafetyProcessing and curing release fumes and residual monomer vapours, so ventilate mixing and vulcanising areas. Carbon black dust soils skin and lungs, and burning rubber gives dense toxic smoke.

Nitrile rubber is a copolymer of butadiene and acrylonitrile, with acrylonitrile content from about 18% to 50%. A higher nitrile level improves resistance to petroleum oils and fuels but reduces low-temperature flexibility, making it the standard seal rubber for oil systems.

PropertiesDensity approx. 1.0 g/cm3, service roughly -30 to 100 °C (specialised grades higher), excellent resistance to mineral oils and fuels, good abrasion resistance, but poor ozone, weather and polar solvent resistance.

ApplicationsO-rings, oil seals, fuel and hydraulic hoses, gaskets, diaphragms, printing rollers and disposable oil-resistant gloves.

SafetyBurning or severe overheating can release hydrogen cyanide and nitrogen oxides, so never incinerate or weld near it. Avoid ketones and esters, which swell it, and ensure ventilation in storage.

EPDM is ethylene-propylene-diene rubber, a saturated-backbone elastomer cured with sulphur or peroxide. Its backbone resists ozone, weather, steam and polar fluids, making it the standard outdoor seal rubber, but it swells badly in mineral oils and fuels.

PropertiesCompounds approx. 1.1-1.3 g/cm3, service roughly -50 to 150 °C, excellent ozone, weather, hot water and steam resistance, good electrical insulation, but poor resistance to petroleum oils and hydrocarbons.

ApplicationsAutomotive door and window seals, radiator hoses, roofing membranes, steam hoses, glycol-based brake seals, cable insulation and swimming-pool liners.

SafetyNever fit EPDM in contact with mineral oil, grease or fuel, since swelling causes seal failure. Burning gives dense black smoke, and keep peroxide curatives away from heat and flame.

Neoprene is the DuPont trade name for polychloroprene (CR), a chlorine-containing synthetic rubber. It balances moderate oil resistance, good weathering and ozone resistance and inherent flame retardancy, which is why it serves in demanding but general conditions.

PropertiesDensity approx. 1.23 g/cm3, service roughly -40 to 100 °C, good ozone, weather and flame resistance, moderate oil resistance, good flex fatigue, and fair compression set.

ApplicationsWetsuits, power transmission belts, cable jackets, bridge bearings, hose covers, gaskets, adhesives and engine-compartment boots.

SafetyBurning releases hydrogen chloride, so keep away from open flame and welding. Solvent-based contact adhesives are flammable and need ventilation, and uncured stocks should be stored cool to avoid scorching.

Silicone rubber is a polysiloxane elastomer with a silicon-oxygen backbone, cured by peroxide, platinum or condensation chemistry. It stays flexible over a very wide temperature range and is inert and physiologically neutral, though mechanically weaker than organic rubbers.

PropertiesDensity approx. 1.1-1.5 g/cm3, service roughly -55 to 200 °C (some grades higher), low tensile strength (about 4-10 MPa), excellent electrical insulation, high gas permeability, and poor tear and abrasion resistance.

ApplicationsOven and appliance gaskets, medical tubing, baking moulds, keypads, spark-plug boots, cable insulation and baby-bottle teats.

SafetyAcetoxy-cure sealants release acetic acid vapour while curing, so ventilate. Burning silicone leaves abrasive silica ash, and oils and fluids extracted from it can contaminate painted surfaces.

Viton is the Chemours trade name for fluoroelastomers, designated FKM. Their high fluorine content gives outstanding resistance to heat, oils, fuels and many acids, which justifies their much higher price compared with NBR in hot, aggressive fluid service.

PropertiesDensity approx. 1.8-1.9 g/cm3, continuous service to roughly 200-230 °C, excellent resistance to oils, fuels and acids, poor resistance to ketones, amines and hot steam, and limited low-temperature flexibility.

ApplicationsFuel-system O-rings, crankshaft and valve-stem seals, chemical pump seals, aerospace sealing and semiconductor process equipment.

SafetyAbove about 300 °C it decomposes, releasing toxic hydrogen fluoride; never burn it, and wear gloves when handling fire-damaged FKM seals. Keep away from tobacco and flames.

Polyurethane elastomer is normally a cast or millable thermoset made by reacting a polyol with an isocyanate and a chain extender. It carries loads and resists abrasion better than most rubbers, bridging the gap between rubber and hard plastic.

PropertiesDensity approx. 1.1-1.25 g/cm3, hardness from about Shore 60A to 75D, outstanding abrasion and tear resistance, high load capacity, service roughly -30 to 80 °C, and ester types hydrolyse in hot water.

ApplicationsIndustrial rollers and wheels, hydraulic seals, cyclone and screen liners, bushes, couplings, mining screens and conveyor scrapers.

SafetyIsocyanate prepolymers are respiratory sensitisers, so cast in ventilated areas with proper protection. Some curatives such as MOCA are suspected carcinogens; follow the SDS and avoid skin contact.

Butyl rubber is a copolymer of isobutylene with a few percent of isoprene (IIR). Its tightly packed chains give extremely low gas permeability and good damping, but it cures slowly and swells in petroleum oils.

PropertiesDensity approx. 0.92 g/cm3, service roughly -40 to 120 °C, very low gas and moisture permeability, good ozone, weather and chemical resistance, high damping, and poor oil resistance.

ApplicationsTyre inner tubes and tubeless inner liners, pharmaceutical vial stoppers, roofing membranes, vibration dampers, hose linings and sealants.

SafetyKeep it away from mineral oils and solvents, which cause swelling and failure. Butyl is flammable, and halobutyl compounds release acidic gases when burned, so avoid hot work nearby.

Hypalon is the DuPont trade name for chlorosulfonated polyethylene, standard term CSM, a chlorine- and sulphur-bearing synthetic rubber. It is notable for ozone, weather and oxidising-chemical resistance with stable colours, but the original brand has been discontinued.

PropertiesDensity approx. 1.1-1.3 g/cm3, service up to roughly 120 °C, outstanding ozone, UV and weather resistance, good resistance to oxidising chemicals and acids, fair oil resistance, and moderate compression set.

ApplicationsRoofing membranes, inflatable boats such as rigid inflatables, chemical tank linings, cable jackets, pond liners and industrial hoses.

SafetyBurning releases hydrogen chloride and sulphur dioxide, so avoid hot work close to it. Solvent-based adhesives used for seaming are flammable and need ventilation and non-sparking tools.

Thermoplastic elastomers are rubbery materials that melt and can be moulded like plastics, such as SBS and SEBS block copolymers, thermoplastic vulcanisates and olefinic types. They need no vulcanisation and are recyclable, but tolerate less heat than thermoset rubber.

PropertiesDensity approx. 0.9-1.3 g/cm3, hardness roughly Shore 20A to 60D, easily injection-moulded and extruded, service typically -40 to 100 °C, and higher compression set than vulcanised rubber.

ApplicationsSoft-touch grips and handles, seals and gaskets, medical tubing, cable jackets, bellows, toothbrush handles and overmoulded tool parts.

SafetyOverheating during moulding causes degradation and irritating fume, so control melt temperature and ventilate. Molten polymer and hot barrels cause burns, and purge machines properly.

Thermoplastic polyurethane is a melt-processable block copolymer of hard and soft segments, with polyester or polyether soft types. Unlike cast polyurethane elastomer, it can be injection moulded, extruded and 3D printed, while keeping strong abrasion and tear resistance.

PropertiesDensity approx. 1.1-1.25 g/cm3, hardness about Shore 60A to 75D, tensile strength often 25-60 MPa, excellent abrasion and tear resistance, service roughly -40 to 90 °C, and absorbs moisture before processing.

ApplicationsHoses, cable sheathing, caster wheels, phone cases, ski-boot shells, 3D-printing filament, films and footwear soles.

SafetyIt absorbs moisture and must be dried before processing, or bubbles and degradation result. Overheating releases irritating decomposition fumes, including isocyanates, so ventilate and watch melt temperature.

Aluminium oxide (Al2O3), the most common technical ceramic, supplied at purities from about 85% to over 99.5%. It is hard, electrically insulating and chemically stable, and it is produced by pressing and sintering powder, giving a cost-effective balance of properties.

PropertiesDensity approx. 3.7-3.98 g/cm3; melting point approx. 2,070 °C; hardness around 9 on the Mohs scale; flexural strength approx. 300-400 MPa; excellent insulation and wear resistance but brittle.

ApplicationsWear liners, spark plug insulators, substrates for electronics, pump seals, cutting tool inserts, furnace tubes, grinding media and biomedical hip components.

SafetyFine ceramic dust is a respiratory irritant, so extract during grinding or sawing. Fired parts are brittle and can chip into sharp fragments, and thermal shock can crack them.

A synthetic compound of silicon and carbon made by sintering, reaction bonding or the Acheson process. It combines extreme hardness, high thermal conductivity and low thermal expansion, so it serves where abrasion and heat meet.

PropertiesDensity approx. 3.1-3.2 g/cm3; hardness approx. 9.5 Mohs; decomposes rather than melts near 2,700 °C; high thermal conductivity, good thermal shock resistance, and strong resistance to acids.

ApplicationsMechanical seal faces, abrasive wheels and sandpaper, kiln furniture, heating elements, furnace linings, armour tiles, and power semiconductor substrates.

SafetyMachining and grinding produce hard abrasive dust that irritates lungs and eyes, so use wet methods or extraction. Work only with diamond tooling, and wear gloves around sharp broken edges.

A covalent ceramic made by reaction bonding, hot pressing or gas-pressure sintering of silicon and nitrogen. Its elongated grain structure gives high toughness for a ceramic, and its good thermal shock resistance suits it to rolling and hot service.

PropertiesDensity approx. 3.2-3.3 g/cm3; flexural strength approx. 700-1,000 MPa for dense grades; fracture toughness approx. 6-7 MPa·m^0.5; service up to roughly 1,200-1,300 °C; high wear resistance.

ApplicationsHybrid ceramic bearing balls, turbocharger rotors, cutting tool inserts, molten-aluminium handling parts, glow plugs, and welding fixtures.

SafetyDust from grinding is irritating and fine powders should be handled with ventilation. Components are hard but brittle, so avoid impact loads and use diamond tooling for finishing.

Zirconium dioxide (ZrO2), usually stabilised with yttria so its tetragonal phase transforms under stress and blocks cracks. This transformation toughening makes it the toughest of the oxide ceramics, while its low thermal conductivity also gives useful insulation.

PropertiesDensity approx. 6.0 g/cm3; flexural strength approx. 900-1,200 MPa for yttria-stabilised grades; fracture toughness approx. 5-10 MPa·m^0.5; low thermal conductivity; becomes ionically conductive at high temperature.

ApplicationsDental crowns, ceramic knife blades, oxygen sensors, fuel cell electrolytes, thermal barrier coatings, bearing and pump parts, and wire-drawing dies.

SafetyMachine only with diamond tools and extract dust. Zirconia powders may contain trace radioactive impurities, so follow supplier guidance, and avoid long hot exposure of unstabilised grades that can crack by phase change.

A very hard ceramic (B4C) produced by carbothermal reduction of boron oxide and then hot pressing. It is among the hardest known materials and also very light, so it is used in armour and where neutron absorption is needed.

PropertiesDensity approx. 2.5 g/cm3; hardness approx. 2,800-3,500 HV, third hardest after diamond and cubic boron nitride; melting point approx. 2,450 °C; brittle and expensive to sinter.

ApplicationsBallistic armour plates for personnel and vehicles, sand-blasting nozzles, neutron-absorbing control rods and shielding in nuclear plants, and abrasive lapping powder.

SafetyFine powder and dust are respiratory hazards; use dust control and eye protection. Hard but brittle plates shatter on impact, and it reacts with ferrous metals when hot, so it is unsuitable for machining steel.

A vitrified ceramic fired from clay, feldspar and quartz at about 1,250-1,400 °C. The glassy phase fills pores and a glaze gives a smooth, nonabsorbent surface, so electrical porcelain is used as a durable high-voltage insulator.

PropertiesDensity approx. 2.3-2.5 g/cm3; high dielectric strength and compressive strength; non-porous and chemically resistant when glazed, but brittle with moderate tensile strength and sensitivity to thermal shock.

ApplicationsHigh-voltage line and post insulators, bushings, fuse bodies, spark plug insulators, sanitary ware, laboratory crucibles and tableware.

SafetyInsulators are heavy and can shatter, so use lifting aids and protective gear. Chipped glazed edges are sharp, and silica-containing dust arises during cutting or grinding of fired body.

A magnesium silicate ceramic made mostly from talc (steatite) with a small flux content, fired to a dense body. Its low dielectric loss at high frequency and good mechanical strength make it a standard electrical insulator in heating and radio-frequency equipment.

PropertiesDensity approx. 2.6-2.9 g/cm3; low dielectric loss, good dimensional accuracy after firing and arc resistance; stronger than porcelain in compression, but poor thermal shock resistance.

ApplicationsHeater element supports and bobbins, high-frequency insulators, thermostat and switch parts, fuse holders, and cable bushings.

SafetyTalc dust irritates lungs, so control dust when machining unfired or green bodies and use extraction. Source from asbestos-free talc; fired parts are brittle and can fracture under thermal shock.

A magnesium aluminium silicate ceramic (2MgO·2Al2O3·5SiO2) known for its very low thermal expansion. That lets it survive rapid heating and cooling, so it is used in honeycomb catalyst carriers, kiln furniture and burner parts. It is porous and lightweight.

PropertiesDensity approx. 2.1-2.6 g/cm3 depending on porosity; thermal expansion extremely low, around 1-3 x 10^-6 per K; excellent thermal shock resistance, with moderate strength and use up to about 1,200-1,300 °C.

ApplicationsCatalytic converter honeycomb substrates, diesel particulate filters, kiln shelves and setters, burner nozzles, and heat-exchanger components.

SafetyCutting or cleaning generates fine silicate dust, so wear respirators and use extraction. Honeycomb parts are fragile, and used filters may hold soot or heavy-metal residues.

An aluminosilicate ceramic (3Al2O3·2SiO2) that forms naturally at high temperature and is produced synthetically by sintering or fusing alumina and silica. It offers good creep resistance and low thermal expansion, so it keeps strength in hot furnaces.

PropertiesDensity approx. 2.8-3.1 g/cm3; decomposes incongruently near 1,840 °C; thermal expansion approx. 5 x 10^-6 per K; good creep and thermal shock resistance and low thermal conductivity.

ApplicationsKiln furniture and setters, furnace tubes and thermocouple sheaths, refractory linings, protective tubes in glass and metal processing, and electronic substrates.

SafetyFine dust from cutting or demolition is a respiratory hazard, with possible crystalline silica content. Use dust extraction; hot parts remain dangerous long after furnace shutdown.

A refractory clay with moderate alumina content, mostly kaolinite, that resists high temperature without softening. It is mixed and fired into fireclay bricks, shapes and mortars, and is the lowest-cost general-purpose refractory material available to industry.

PropertiesAlumina content typically approx. 25-45%; refractoriness roughly 1,500-1,700 °C by pyrometric cone equivalent; low cost and good thermal shock resistance, but weaker against basic slags and erosion than high-alumina products.

ApplicationsLining of boilers, chimney flues, domestic stoves, kilns, brick-making furnaces, foundry ladles and ordinary forge hearths.

SafetyDry grinding, mixing and used-lining removal raise silica and cristobalite dust. Wear respirators, wet down demolition work, and allow hot structures to cool before entry.

Shaped, fired or chemically bonded blocks for furnace walls, grouped by chemistry: fireclay, high-alumina, silica, magnesia and magnesia-chrome or carbon types. Unlike loose fire clay, these are pre-formed units chosen to match the slag and temperature of each zone.

PropertiesMax service temperature spans from roughly 1,300 °C for fireclay to over 1,700 °C for magnesia or high-alumina; key properties are refractoriness under load, porosity, slag resistance and thermal shock behaviour.

ApplicationsLining of blast furnaces, steel ladles, cement kilns, glass tanks, boilers, incinerators, coke ovens and foundry furnaces.

SafetyBricks are heavy and cut-prone, so use team lifts. Cutting generates silica and alumina dust; used chrome-bearing bricks may contain hazardous chromium compounds and need careful disposal.

Lightweight insulation made by spinning or blowing molten alumina-silica into fibres, then forming blankets, boards, papers and modules. Its very low density and thermal conductivity cut heat loss, which makes it widely used for lining furnaces and thermal insulation.

PropertiesBlanket density approx. 64-192 kg/m3; classification temperatures up to about 1,260 °C for alumina-silica and higher for zirconia or alumina grades; low thermal conductivity, low heat storage and good thermal shock resistance.

ApplicationsFurnace and kiln hot-face linings, expansion joint seals, heat-treatment oven doors, high-temperature gaskets, fire-protection wraps, and exhaust and turbine insulation.

SafetyRefractory ceramic fibre is classified as a suspected carcinogen in many regions; use respirators, protective clothing, damp handling and vacuum cleaning. Heated fibre can form crystalline silica, so avoid dry sweeping.

A material made by melting and forming a glass, then heat treating it so fine crystals grow inside the glass in a controlled way. The result is non-porous and can have near-zero thermal expansion, giving unusual resistance to thermal shock.

PropertiesDensity approx. 2.4-2.6 g/cm3; thermal expansion can be near zero in cooktop and mirror-substrate grades; non-porous, hard, chemically stable, and stronger than the parent glass but brittle.

ApplicationsCooktop panels, telescope mirror blanks, laboratory hotplates, fireplace and oven windows, dental restorations, and ceramic cookware.

SafetyBroken pieces are razor sharp, so use gloves and eye protection. Do not subject it to impact on edges or to heating beyond rated temperature; cutting dust requires extraction.

Not a single standard material, the term normally means carbon-bonded refractories in which graphite is combined with ceramic oxides, such as alumina-graphite, magnesia-carbon bricks and clay-graphite crucibles. Graphite adds thermal conductivity and keeps molten metal and slag from wetting the refractory.

PropertiesGraphite content typically approx. 5-30%; good thermal shock resistance, high thermal conductivity and poor slag wetting; weakness is oxidation of the carbon in air at several hundred degrees Celsius unless protected.

ApplicationsSteel ladle slag lines, magnesia-carbon converter linings, continuous casting nozzles and stoppers, and clay-graphite crucibles for melting brass, bronze and aluminium.

SafetyCarbon dust is combustible and conductive, so keep it away from electrical equipment and ignition sources. Hot refractory in air burns away, giving carbon monoxide risk in poorly ventilated spaces.

Soda-lime glass is the common commercial glass, made from roughly 70-74% silica with sodium and calcium oxides, melted from sand, soda ash and limestone. It is cheap, easy to form and recyclable, but handles thermal shock poorly.

PropertiesDensity approx. 2.5 g/cm3, softening point about 700-730 °C, thermal expansion approx. 9 x 10^-6 per K, Young's modulus around 70 GPa, and poor resistance to sudden temperature changes.

ApplicationsWindow panes, bottles and jars, drinking glasses, light bulbs, mirrors, float glass for buildings and vehicles and the base for tempered and laminated glass.

SafetyBroken edges are razor-sharp, so wear cut-resistant gloves and eye protection. Do not heat it unevenly or pour boiling liquid into it, and lift large sheets with suction cups.

Borosilicate glass contains roughly 80% silica and 12-13% boron trioxide, giving a much lower thermal expansion than soda-lime. This makes it resistant to thermal shock and chemically durable, so it is standard in laboratories and ovenware.

PropertiesDensity approx. 2.2-2.3 g/cm3, thermal expansion approx. 3.3 x 10^-6 per K for common types, softening point near 820 °C, excellent chemical durability and good thermal shock resistance.

ApplicationsLaboratory beakers and flasks, process pipelines, oven dishes, sight glasses, gauge glasses, high-power lamp envelopes and pharmaceutical vials.

SafetyIt still breaks under thermal shock if scratched or chipped, so inspect glassware before heating. Vacuum or pressurised vessels can implode; never heat closed vessels, and use eye protection.

Tempered glass is soda-lime glass heated to roughly 620-650 °C and rapidly air-quenched, leaving the surface in compression and the core in tension. It is several times stronger than annealed glass and breaks into small blunt pieces, but cannot be cut afterwards.

PropertiesDensity approx. 2.5 g/cm3, surface compression commonly 69 MPa or more, flexural strength roughly four to five times that of annealed glass, and breakage into small granular fragments.

ApplicationsCar side and rear windows, shower enclosures, glass doors, table tops, appliance panels, balustrades and facade glazing.

SafetyCut, drill and edge all work before tempering, since the pane will shatter if worked afterwards. Edge damage can trigger sudden failure, and nickel-sulphide inclusions can cause rare spontaneous breakage.

Laminated glass bonds two or more glass sheets with an interlayer such as PVB, EVA or ionoplast under heat and pressure. If broken, the fragments stay attached to the interlayer, so the pane remains in place and keeps its barrier function.

PropertiesGlass density approx. 2.5 g/cm3, interlayers commonly 0.38 mm PVB multiples, good impact retention and acoustic damping, blocks more than 99% of UV, and holds fragments after cracking.

ApplicationsCar windscreens, overhead and facade glazing, security and bullet-resistant glazing, balustrades, aquarium panels and sound-insulating windows.

SafetyExposed edges can delaminate if left wet, so protect edges with sealant or framing. Cracked panes stay in place but must still be replaced, and large units are heavy to handle.

Fused silica is amorphous, high-purity silicon dioxide, often made synthetically by flame hydrolysis of silicon tetrachloride. It combines very low thermal expansion with transparency from the deep ultraviolet to the infrared, which no ordinary glass offers.

PropertiesDensity approx. 2.2 g/cm3, thermal expansion approx. 0.55 x 10^-6 per K, refractive index near 1.458, UV transmission down to roughly 160-180 nm, and a very high softening temperature near 1600 °C.

ApplicationsUV and laser optics, semiconductor photomask substrates, optical-fibre preforms, space telescope components and precision windows.

SafetyFractured pieces are sharp, and hydrofluoric acid used for etching is extremely hazardous. Grinding or devitrified material may generate crystalline silica dust, so use wet methods and extraction.

Quartz glass is the industrial term for glass made by melting natural quartz crystal or sand, often called fused quartz. Compared with synthetic fused silica, it usually holds more trace impurities, but it is cheaper and still withstands very high temperature.

PropertiesDensity approx. 2.2 g/cm3, continuous use up to roughly 1100 °C and short exposure higher, very low thermal expansion, high chemical resistance except to hydrofluoric acid and hot alkalis, and good UV transmission.

ApplicationsFurnace and diffusion tubes, halogen and UV lamp envelopes, crucibles for silicon growth, laboratory ware and protective sleeves for sensors.

SafetyHot quartz looks like cold glass, so handle with tongs and gloves. Fingerprints can devitrify the surface at high temperature, and devitrified cristobalite dust is a silicosis hazard.

Fiberglass is glass drawn into fine filaments, usually E-glass, and supplied as chopped strands, woven roving, mat or insulation wool. Embedded in polyester, vinyl ester or epoxy resin, it forms glass-reinforced plastic (GRP) with high strength for its weight.

PropertiesE-glass filament density approx. 2.55 g/cm3, filament tensile strength several GPa and modulus approx. 72 GPa, non-conductive and non-combustible, with GRP laminates typically 100-400 MPa depending on layup.

ApplicationsBoat hulls, tanks and pipes, wind-turbine blades, printed-circuit boards, thermal insulation, roofing sheets, car body panels and filtration media.

SafetyFibres and cutting dust irritate skin, eyes and throat, so wear sleeves, gloves, goggles and a particulate respirator. Resin styrene vapour and catalyst peroxide are fire hazards during lay-up.

Optical glass is made to tight standards of refractive index, homogeneity and low striae, and is divided into crown and flint types. Controlled melting and fine annealing give predictable bending and dispersion of light for lenses and prisms.

PropertiesBK7 borosilicate crown has refractive index near 1.517 and Abbe number near 64, density approx. 2.5 g/cm3, and transmits from roughly 350 nm to 2 µm, while flint glasses disperse light more strongly.

ApplicationsCamera, microscope and telescope lenses, prisms, binoculars, spectacle lenses, laser windows, rangefinders and projector optics.

SafetySurfaces scratch and stain from touch, so handle with gloves and lens tissue. Older glasses may contain lead, and polishing slurries and dust need control; follow the manufacturer safety data sheet.

Low-E glass is float glass with a microscopically thin metallic or metal-oxide coating that reflects long-wave infrared heat. Pyrolytic hard coats are applied on the float line, while sputtered silver soft coats must sit inside a sealed double-glazed unit.

PropertiesCoating emissivity approx. 0.04-0.2 versus about 0.84 for plain glass, double-glazed U-value falling from around 2.8 to roughly 1.1-1.6 W/m2.K, and visible transmission typically 60-80%.

ApplicationsDouble-glazed windows, curtain-wall facades, refrigerated display doors, greenhouses, skylights and energy-efficient vehicle glazing in cold or hot climates.

SafetySoft coatings scratch and corrode if exposed, so keep edges sealed and handle only with clean gloves. Fit coated faces in the specified position, and plan for heavy, sharp-edged panes.

Ceramic glass is the standard industrial term glass-ceramic, a material melted as glass and then heat-treated so tiny crystals grow within it. Lithium aluminosilicate types such as Ceran, Robax and Zerodur have near-zero thermal expansion, unlike ordinary glass.

PropertiesDensity approx. 2.5 g/cm3, thermal expansion near zero (about 0 to 1 x 10^-6 per K), continuous use of cooktop types to roughly 700 °C, high thermal shock resistance and chemical durability.

ApplicationsInduction and radiant cooktop panels, stove and fireplace doors, telescope mirror blanks, laboratory hotplates and oven windows.

SafetyHot surfaces look unchanged, so rely on residual-heat indicators. Sharp point impacts or edge strikes can shatter panels, and spilled sugar fused onto a hot surface can pit it.

The common trade term for glass-fibre-reinforced thermoset laminates, typically polyester or vinyl ester resin, made by hand lay-up, spray-up or pultrusion. In practice it means large corrosion-proof structures such as tanks and grating, built cheaply rather than optimised for stiffness.

PropertiesDensity approx. 1.5-2.0 g/cm3; tensile strength roughly 70-300 MPa depending on fibre form and content; excellent corrosion, weather and electrical insulation properties, with relatively low stiffness compared with metals.

ApplicationsChemical storage tanks, cooling tower parts, walkway grating, pipes and ducts, boat hulls, truck body panels, and non-conductive ladders.

SafetyStyrene vapour during lay-up needs ventilation and respirators. Cutting and sanding release glass dust and fibres that irritate skin and lungs; handle resin catalysts carefully.

A composite in which carbon fibres, usually in an epoxy matrix, carry the load. Aligned fibres give extremely high specific stiffness and fatigue resistance, so CFRP is selected for weight-critical structures despite its higher cost.

PropertiesDensity approx. 1.5-1.6 g/cm3; unidirectional tensile strength along fibres roughly 1,000-2,500 MPa with modulus around 120-150 GPa for standard fibres; low thermal expansion, but anisotropic and low impact tolerance.

ApplicationsAircraft fuselage and wing parts, racing car monocoques, bicycle frames, drone arms, pressure vessels, wind turbine blades, and robot arm structures.

SafetyConductive carbon dust can short electrical cabinets, and fibres irritate skin and lungs when cutting or sanding. Contact with aluminium or steel can cause galvanic corrosion; use proper PPE and extraction.

Glass fibres in a polymer matrix, usually used for engineered structural profiles and reinforcement rather than general fibreglass moulding. As compared with generic FRP, the term stresses designed fibre layouts such as pultruded shapes, rebar and filament-wound pipe.

PropertiesDensity approx. 1.9-2.1 g/cm3; unidirectional glass-epoxy tensile strength roughly 600-1,000 MPa with modulus around 35-45 GPa; electrically insulating, corrosion-proof, and lower stiffness than carbon composites.

ApplicationsPultruded structural beams, GFRP rebar in corrosive concrete, leaf springs, wind turbine blades, filament-wound pipes and pressure vessels, and electrical insulators.

SafetyCutting and drilling generate irritating glass-fibre dust, so wear gloves, long sleeves, respirator and use extraction. Uncured resin is a skin sensitiser; keep ignition sources away from styrene resins.

A laminate in which aramid (Kevlar or Twaron type) fabric reinforces epoxy or other resin. It trades some compressive strength for outstanding impact, vibration damping and ballistic energy absorption at lower weight than glass composites.

PropertiesDensity approx. 1.3-1.4 g/cm3; tensile strength is high with good toughness and damage tolerance, but compressive and bending strength are relatively poor; absorbs moisture and is degraded by prolonged UV.

ApplicationsBallistic panels and helmets, boat hulls and canoes, aircraft fairings, protective vehicle liners, and impact-resistant sports equipment.

SafetyFibres fray and are hard to cut, so use dedicated aramid shears and gloves. Machining dust is irritating, and exposed surfaces need UV protection and moisture sealing.

The reinforcing fibre itself, usually made by heating polyacrylonitrile (PAN) precursor to produce long thin filaments of mostly carbon. Supplied as tow, fabric or chopped strand, it is the load-carrying component of CFRP rather than a finished structural material.

PropertiesFilament diameter approx. 5-10 µm; density approx. 1.75-1.95 g/cm3; tensile strength roughly 3-7 GPa and modulus approx. 230-600 GPa; electrically conductive, very low thermal expansion, oxidises in air at high temperature.

ApplicationsReinforcement for composite aircraft parts, sports equipment, wind blades, friction materials, heating elements, and conductive fabrics.

SafetyLoose filaments and dust are electrically conductive and can short equipment; they also irritate skin and eyes. Handle with gloves, avoid dry sanding, and burn only under controlled conditions as fibres become airborne.

Thin filaments drawn from molten glass, most often E-glass, collected as roving, mat and woven cloth. It is the lowest-cost structural reinforcement for plastics and also serves for thermal insulation, electrical laminates and filtration media.

PropertiesE-glass density approx. 2.55-2.6 g/cm3; virgin filament tensile strength approx. 3.4 GPa; modulus approx. 72 GPa; softens near 840 °C; non-combustible and electrically insulating but notch sensitive.

ApplicationsReinforcement for GFRP and FRP parts, printed circuit board laminates, thermal insulation batts, filter cloths, roofing shingles, and cable reinforcement.

SafetyFibres cause itching and skin, eye and respiratory irritation. Wear gloves, long sleeves and a dust mask when handling or cutting, and wash with cool water rather than rubbing.

A synthetic para-aramid fibre (Kevlar, Twaron type) spun from rigid aromatic polyamide chains. It has very high tensile strength for its weight and resists cuts and abrasion, but it does not melt and is sensitive to UV light.

PropertiesDensity approx. 1.44 g/cm3; tensile strength roughly 2.8-3.6 GPa with modulus approx. 60-130 GPa; decomposes around 450-500 °C rather than melting; weak in compression and moisture-sensitive.

ApplicationsBody armour and helmets, cut-resistant gloves, ropes and cables, belt and hose reinforcement, tyre cord, and brake and clutch friction pads.

SafetyCut only with aramid-rated shears. Avoid fibre dust inhalation when machining, protect stored material from UV and moisture, and do not rely on it as flame barrier at high temperature.

A structural panel with two thin, strong face sheets bonded to a thick, light core such as foam, balsa or honeycomb. Separating the skins increases bending stiffness enormously at little added weight, so panels are common in aircraft, boats and trucks.

PropertiesOverall density is low, often well under 1 g/cm3 for the panel; bending stiffness rises roughly with the square of core thickness; properties depend on face material, core density and adhesive bond quality.

ApplicationsAircraft floor and wing panels, boat decks and hulls, truck and rail bodies, wind turbine blade shells, cleanroom walls, and cold store panels.

SafetyCut edges expose the core to water ingress and must be sealed. Dust from foam, glass or carbon skins needs extraction; avoid point loads that crush the core, and ventilate when bonding.

A hexagonal-celled core material, made from aluminium foil, Nomex aramid paper or thermoplastic, used as the lightweight middle layer of sandwich panels. It gives high compressive and shear strength per unit weight, and open cells allow venting.

PropertiesCore density approx. 16-200 kg/m3 depending on cell size and wall thickness; high specific compressive and shear strength; aluminium types resist heat, while Nomex is fire retardant and non-corroding.

ApplicationsAircraft floors, flaps and nacelles, rail and ship interior panels, satellite structures, acoustic liners, and honeycomb filters.

SafetyFoil edges are razor sharp and Nomex cuts give irritating dust, so wear gloves and masks. Crushed or wet honeycomb is weakened; seal against moisture and avoid contact between aluminium and carbon skins.

A metal such as aluminium, magnesium or titanium reinforced with ceramic particles, whiskers or fibres such as silicon carbide. It gains stiffness, wear resistance and thermal control, and keeps higher temperature capability than polymer composites.

PropertiesAluminium-silicon carbide grades have density approx. 2.8-3.0 g/cm3 with much higher stiffness and wear resistance than the base alloy, tailored thermal expansion, and reduced ductility and machinability.

ApplicationsBrake rotors, piston and cylinder liners, electronic heat-sink baseplates, aerospace struts, bicycle and golf components, and engine parts.

SafetyAbrasive ceramic particles quickly wear tools, so use diamond or carbide tooling. Fine aluminium swarf and dust is combustible, and cutting dust contains hard particles that need extraction.

A ceramic matrix, often silicon carbide or alumina, strengthened by ceramic or carbon fibres so cracks are bridged instead of running through. It removes much of the brittleness of monolithic ceramics while retaining heat tolerance.

PropertiesService temperatures can reach roughly 1,200-1,400 °C for SiC/SiC systems; density approx. 2-3 g/cm3, around a third of nickel superalloys; far better damage tolerance than plain ceramics but costly and hard to produce.

ApplicationsGas turbine shrouds and combustor liners, aircraft engine nozzles, carbon-ceramic brake discs, rocket nozzles, and heat-shield parts.

SafetyMachining uses diamond tools and creates fine ceramic and fibre dust, so extraction and respirators are needed. Parts stay hot for a long time and can fail abruptly if damaged.

A blend of wood flour or fibre, typically 50-70%, with polyethylene, polypropylene or PVC, extruded or moulded into boards and profiles. It looks like timber but resists rot and splintering, with less maintenance outdoors, which suits decking.

PropertiesDensity approx. 1.0-1.4 g/cm3; higher thermal expansion and creep than wood; absorbs some moisture and can show mould and UV fading; stiffness is lower than solid timber.

ApplicationsOutdoor decking boards, railings, fencing, wall cladding, window frames, automotive interior door panels, and garden furniture.

SafetyWood dust is combustible and a respiratory hazard in compounding and cutting, so control dust and ignition. Wet surfaces can be slippery, and boards burn, so check fire rating for building use.

Electrolytic tough pitch copper of about 99.9% purity, drawn into wire or rolled into strip, is the reference conductor for power and signal wiring. Engineers choose it for low resistivity, easy jointing and good behaviour at terminations, despite higher cost and weight than aluminium.

PropertiesResistivity approx. 1.72 x 10^-8 ohm-m at 20 C (about 100% IACS), density approx. 8.9 g/cm3, melting point approx. 1085 C, with good ductility, solderability and corrosion resistance in normal air.

ApplicationsBuilding wiring, motor and transformer windings, flexible cables, earthing conductors, switchgear connections and PCB tracks where compact size and reliable terminations matter.

SafetyHeavy coils cause lifting injuries and cut strand ends are sharp. Always isolate and prove circuits dead before work, and extract fumes and oxide dust produced by hot work or grinding.

Electrical-grade aluminium, such as EC grade 1350 or alloy 6201 for overhead lines, offers roughly 61% of copper's conductivity at about a third of the weight. Larger cross-sections make up the difference, which makes it economical for long-distance power distribution.

PropertiesDensity approx. 2.7 g/cm3, resistivity approx. 2.8 x 10^-8 ohm-m (about 61% IACS), melting point approx. 660 C; it forms an insulating oxide film and expands more than copper when heated.

ApplicationsOverhead transmission lines (ACSR), service cables, bus trunking, large distribution feeders and underground power cables where weight and material cost dominate.

SafetyOxide film causes high-resistance joints, so wire-brush, apply oxide-inhibiting compound and use aluminium-rated lugs to avoid overheating. Avoid damp contact with copper, which sets up galvanic corrosion; fine dust is combustible.

Polyvinyl chloride compounded with plasticisers, stabilisers and fillers is the most common low-voltage cable insulation and sheath. It is cheap, flexible, naturally flame retardant because of its chlorine content, and easy to extrude in many colours for wire identification.

PropertiesDensity approx. 1.3-1.5 g/cm3, conductor rating typically 70 C continuous (90 C for heat-resistant grades), good dielectric strength and self-extinguishing behaviour, but it softens when hot and stiffens in cold.

ApplicationsBuilding wires, house-wiring cables, control cables, appliance flexes and sheathing on low-voltage power cables up to 1.1 kV.

SafetyBurning or overheating releases hydrogen chloride and dense smoke, which are corrosive and irritant, so low-smoke zero-halogen cable is preferred in tunnels and crowded buildings. Plasticiser loss makes aged insulation brittle.

Cross-linked polyethylene is polyethylene whose molecular chains are joined into a network by peroxide, silane or radiation, so it does not melt like ordinary PE. This gives higher temperature capability and low dielectric loss, which is why it dominates medium- and high-voltage power cables.

PropertiesConductor rating approx. 90 C continuous and approx. 250 C for short circuit, density approx. 0.92-0.95 g/cm3, very low dielectric loss, high volume resistivity and good moisture and chemical resistance.

Applications11 kV to 400 kV underground and submarine power cables, LV armoured cables, solar DC cables and utility distribution feeders.

SafetyBurns readily with dense smoke and flaming drips unless halogen-free flame-retardant compounds are used. Terminations at medium voltage need correct stress-relief and tracking-resistant kits, and cured material cannot be remelted or easily recycled.

Ethylene propylene rubber, an elastomeric copolymer of ethylene and propylene (often EPDM), is cross-linked to form flexible, heat-resistant cable insulation. It stays pliable at low temperature and resists ozone and moisture, so it suits cables that are repeatedly bent.

PropertiesRated approx. 90 C continuous (higher in special grades), density approx. 1.1-1.3 g/cm3 when filled, good flexibility, ozone and weather resistance, but higher dielectric loss than XLPE.

ApplicationsFlexible medium-voltage cables, mining and crane trailing cables, ship and offshore wiring, wind turbine tower cables and railway rolling stock cables.

SafetyFilled rubber compounds burn with heavy smoke, so halogen-free fire-retardant grades are used in confined spaces. Soft insulation is easily nicked by stripping tools, leaving weak spots that later cause insulation failure.

Natural or synthetic rubber compounds, such as natural rubber, SBR, neoprene or silicone rubber, are vulcanised around conductors to make highly flexible insulation and sheath. They suit welding cables, mining trailing cables and appliance leads that must bend repeatedly and survive rough handling.

PropertiesVery flexible even at low temperature, good abrasion and impact resistance, with ratings of approx. 60-90 C for natural or SBR rubber and up to approx. 180 C for silicone; natural rubber ages in ozone, oil and sunlight.

ApplicationsArc welding cables, mining and portable power trailing cables, appliance leads, silicone-insulated heater and oven wiring, and flexible cords on construction sites.

SafetyNatural rubber degrades in sunlight, oil and ozone, so inspect for cracking before use. Latex can trigger allergies, and burning rubber gives dense toxic smoke.

Mica is a naturally occurring layered silicate mineral, mainly muscovite and phlogopite, that splits into thin tough sheets. Mica paper and tapes made from flakes bonded with resin or silicone give insulation that withstands both heat and electrical discharge in machines and heating elements.

PropertiesHigh dielectric strength in thin sheet, thermal stability of approx. 500-600 C for muscovite and approx. 800-900 C for phlogopite, low dielectric loss, and good resistance to corona, arcs and chemicals.

ApplicationsHigh-voltage generator and motor winding tapes, commutator segment insulation, heater supports in toasters and irons, fire-resistant cables and capacitor dielectrics.

SafetyFine mica dust irritates the lungs, so cut and handle with extraction and a dust mask. Thin sheets split into sharp splinters, and resin-bonded tapes can release fumes when first heated.

Kraft or cellulose paper, impregnated with insulating oil or compound, forms a long-established insulation for transformers, bushings and older high-voltage cables. Its low cost and good dielectric performance when oil-filled keep it in use despite its sensitivity to moisture.

PropertiesHigh dielectric strength when oil-impregnated, thermal class A (approx. 105 C), density approx. 0.8-1.2 g/cm3 depending on paper or pressboard, and it absorbs moisture readily, which shortens insulation life.

ApplicationsWinding insulation and pressboard barriers in oil-filled transformers, oil-paper bushings, paper-insulated lead-covered cables and capacitor dielectrics.

SafetyDry paper is combustible and oil-impregnated paper adds to the fire load. Keep it dry before assembly because moisture sharply cuts breakdown strength, and dispose of oil-soaked scrap properly.

Also called magnet wire, this is fine copper wire coated with thin layers of polymer varnish such as polyurethane, polyester-imide or polyamide-imide. The enamel gives turn-to-turn insulation with minimal thickness, allowing tight, compact windings in coils, motors and transformers.

PropertiesThermal class from approx. 130 C to 220 C depending on enamel type, film build of only tens of micrometres, sizes specified in SWG or mm, and solderable grades available for easy termination.

ApplicationsWindings in motors, transformers, relays, inductors, ceiling fans, solenoids, loudspeaker voice coils and automotive alternators, wherever compact insulated coils are needed.

SafetyBurning off enamel for soldering gives irritating fumes, so use extraction. Scratched film causes inter-turn short circuits, and fine wire ends can pierce skin; avoid sharp bends and nicks when winding.

High-conductivity copper, typically ETP grade C101, is rolled or extruded into flat bars, rods or tubes for carrying large currents inside switchgear and panels. Its rigidity, high current capacity and low contact resistance suit tightly packed distribution boards.

PropertiesConductivity at least 100% IACS, density approx. 8.9 g/cm3, rigid and self-supporting, typical design current density of about 1-2 A/mm2 for ventilated bars, and often tin or silver plated at joints.

ApplicationsMain and branch busbars in LV and MV switchgear, motor control centres, transformer terminations, rectifier and electrolysis plants and UPS panels.

SafetyBusbars can deliver very high fault currents, so keep clearances, fit shrouds and sleeves, and never touch without isolation and lockout. Loose bolted joints overheat, and bar edges can cut.

Electrical steel, in its common non-oriented (CRNO) form, is cold-rolled lamination sheet with similar magnetic behaviour in every direction, usually 0.35-0.65 mm thick with an insulating coating. It is stamped into stator and rotor cores where flux direction keeps rotating.

PropertiesLow core loss and high permeability, silicon content roughly 0.5-3% (some grades silicon-free), insulating inter-laminar coating, density approx. 7.6-7.8 g/cm3, and good punchability for mass production.

ApplicationsStator and rotor laminations of induction motors, generators, EV traction motors, fan motors, small transformers, ballasts and relays.

SafetyStamped laminations have sharp burrs that cut hands, so wear cut-resistant gloves. Burrs also short adjacent sheets and raise losses; stacks are heavy, and oily or dusty cutting residues should be controlled.

Silicon steel is an iron alloy with about 3% silicon, and in grain-oriented form (CRGO) the crystals are aligned along the rolling direction by cold rolling and annealing. Silicon raises resistivity and cuts eddy-current loss, so power transformer cores made from it waste little energy.

PropertiesSilicon approx. 3-3.5% in CRGO, density approx. 7.65 g/cm3, saturation flux density approx. 2.0 T, very low core loss and high permeability along the rolling direction but weaker properties across it.

ApplicationsCores of power and distribution transformers, large reactors, current transformers and other devices where the flux direction is fixed.

SafetyThin laminations have razor-sharp edges, and bending, hammering or drilling strains the grain structure and raises losses. Stacks are heavy, and coils should be kept dry to prevent rust.

Refined mineral oil, usually naphthenic or paraffinic, fills transformers to insulate live parts and carry heat from the core and windings to the radiators. Dielectric strength and viscosity are tested routinely, and ester or silicone fluids replace it where fire safety matters.

PropertiesFresh dry oil has high breakdown voltage across a 2.5 mm gap, flash point approx. 140 C or above, density below approx. 0.89 g/cm3, low viscosity and a low pour point.

ApplicationsPower and distribution transformers, reactors, circuit breakers, bushings and instrument transformers for insulation and cooling.

SafetyFlammable, so keep ignition sources away and provide fire protection around oil-filled equipment. Moisture and dissolved gases reduce dielectric strength; very old oil may contain PCBs, so test before handling, and prevent spills reaching drains.

Solutions of alkyd, polyester, epoxy or polyurethane resin in solvent, or solventless resins, are applied to wound coils by dipping or vacuum pressure impregnation. After baking, the varnish bonds turns, fills voids, improves heat transfer and seals against moisture and dirt.

PropertiesAvailable in thermal classes from approx. 130 C (B) to 180 C (H) and above, high dielectric strength after cure, strong bonding of windings, and resistance to moisture, oils and vibration.

ApplicationsImpregnation of motor and transformer windings, rewinding shops, ceiling-fan coils, generator stators and protective coating of electronic assemblies.

SafetySolvent-based varnishes are flammable and release vapours, so ventilate, earth containers and exclude ignition sources. Avoid skin contact, ventilate baking ovens, and keep containers closed and away from heat.

Phenol-formaldehyde thermoset resin, often filled with wood flour or reinforced with paper or cotton layers, was the first fully synthetic plastic. Once moulded and cured under heat and pressure it cannot be remelted, giving hard, rigid, tracking-resistant electrical parts at low cost.

PropertiesDensity approx. 1.3-1.4 g/cm3, good dielectric strength, arc and heat resistance (service roughly 120-150 C), hard and rigid, but brittle and limited to dark colours.

ApplicationsSwitch bases, plug and socket bodies, fuse holders, terminal blocks, laminated paper sheet (SRBP) for panels, and cookware handles.

SafetyMoulding and machining release phenol and formaldehyde vapours and fine dust, so use extraction and dust protection. The brittle material chips under impact, and overheated parts can char and conduct.

Elemental silicon from Group IV, purified to extreme levels and grown as a single crystal, is the basis of most integrated circuits and solar cells. It forms a stable native oxide, SiO2, which provides reliable insulating layers and explains why it displaced germanium.

PropertiesBand gap approx. 1.12 eV at room temperature, density approx. 2.33 g/cm3, melting point approx. 1414 C, diamond cubic crystal structure, and conductivity controlled by doping with boron or phosphorus.

ApplicationsMicroprocessors, memory chips, power MOSFETs and IGBTs, photovoltaic cells and MEMS sensors; metallurgical grade also goes into aluminium alloys and silicones.

SafetyFine silicon dust is combustible and irritates the lungs. Processing uses toxic or pyrophoric gases such as silane, phosphine and arsine and corrosive acids like HF, which need gas cabinets and trained handling.

Germanium is a brittle, silvery-grey Group IV semiconductor that powered the first transistors. Silicon has replaced it in most devices, but its high carrier mobility and infrared transparency keep it useful in detectors, optics and silicon-germanium chips.

PropertiesBand gap approx. 0.66 eV, density approx. 5.32 g/cm3, melting point approx. 938 C, high carrier mobility and infrared transparency, but leakage current rises quickly with temperature.

ApplicationsInfrared lenses and windows for thermal cameras, gamma-ray detectors, SiGe transistors, fibre-optic glass dopant and space solar cell substrates.

SafetyElemental germanium has low toxicity, but gases and compounds such as germane and germanium tetrachloride are toxic or corrosive. Avoid dust, and handle brittle crystals carefully because they cleave and fracture.

Gallium arsenide is a III-V compound semiconductor grown as single crystals or epitaxial layers. Its direct band gap and high electron mobility give efficient light emission and fast operation at microwave frequencies, though wafers cost more and are more fragile than silicon.

PropertiesDirect band gap approx. 1.42 eV, density approx. 5.3 g/cm3, melting point approx. 1238 C, electron mobility several times that of silicon, and semi-insulating substrates are available.

ApplicationsMobile phone RF power amplifiers, LEDs and laser diodes, multi-junction solar cells for satellites, microwave ICs and Hall sensors.

SafetyContains arsenic, so dust from sawing, grinding and scrap is toxic, and strong acids or heat can release arsine. Use extraction and wet processing, and send scrap for controlled hazardous disposal.

Gallium nitride is a wide band gap III-nitride semiconductor, typically grown as thin films on silicon, sapphire or SiC substrates. It sustains high electric fields and switches quickly, so converters and RF amplifiers built on it can be smaller and more efficient.

PropertiesDirect band gap approx. 3.4 eV, density approx. 6.1 g/cm3, high breakdown field and electron mobility in HEMT channels, and good high-temperature tolerance, though substrates are costly and lattice-mismatched.

ApplicationsCompact fast chargers, 5G base station RF amplifiers, blue and white LEDs, laser diodes, radar and data-centre power supplies.

SafetyEpitaxial growth uses ammonia and metal-organic precursors such as trimethylgallium, which are toxic or pyrophoric. Avoid inhaling dust from damaged wafers; fast-switching circuits can still carry lethal voltages.

Silicon carbide is a hard compound of silicon and carbon, grown as single-crystal polytypes (mainly 4H) for semiconductor use. Its wide band gap and high thermal conductivity let power devices run at higher voltage, temperature and frequency than silicon.

PropertiesBand gap approx. 3.26 eV for 4H, density approx. 3.2 g/cm3, thermal conductivity several times that of silicon, very hard (Mohs approx. 9), and it sublimes rather than melts at atmospheric pressure.

ApplicationsEV traction inverters, onboard chargers, solar inverters, railway traction, high-voltage Schottky diodes and MOSFETs; abrasive grades are used for grinding.

SafetyWafers are extremely hard and brittle, leaving sharp fragments, and cutting or polishing creates fine dust that must be controlled. Devices switch fast at high voltage, so discharge DC links before service.

Indium phosphide is a III-V compound semiconductor grown as single-crystal wafers for photonic and very high-frequency electronics. Its band gap suits the 1310 and 1550 nm wavelengths of optical fibre, making it the standard base for telecom lasers and detectors.

PropertiesDirect band gap approx. 1.34 eV, density approx. 4.8 g/cm3, melting point approx. 1060 C, high electron velocity, but mechanically fragile and costly with limited indium supply.

ApplicationsFibre-optic transceiver lasers and photodiodes, coherent optical modulators, millimetre-wave and terahertz transistors, and some high-efficiency solar cells.

SafetyPhosphine can be released if the material contacts acids or is strongly heated, and indium compounds are toxic if inhaled. Use ventilated handling, avoid dust, and treat scrap wafers as hazardous waste.

In PCB manufacturing this means copper foil, electrodeposited or rolled-annealed, laminated onto the faces of an insulating base to form copper-clad laminate. Photo-etching removes unwanted copper, leaving the conductor tracks, pads and planes that interconnect components.

PropertiesCommon weights are 0.5, 1 and 2 oz/ft2 (approx. 17.5, 35 and 70 micrometres), purity of at least 99.8%, with surface roughness and peel strength controlled to limit high-frequency signal loss.

ApplicationsTracks and ground planes in single, double and multilayer boards for consumer electronics, power supplies, automotive control units and telecom equipment.

SafetyEtching uses ferric chloride, ammonium persulphate or acidic cupric chloride, which are corrosive and stain heavily, so wear gloves and goggles. Drilling copper-clad boards makes fine dust, and spent etchant needs proper disposal.

FR-4 is woven E-glass cloth impregnated with a flame-retardant epoxy resin, pressed and cured into rigid sheets. The grade code means self-extinguishing, and it is the default PCB base because it balances cost, strength, insulation and workability.

PropertiesGlass transition temperature approx. 130-180 C, relative permittivity approx. 4.2-4.8 at 1 MHz, density approx. 1.8-1.9 g/cm3, high flexural strength, low water absorption and good tracking resistance.

ApplicationsRigid printed circuit boards, insulating spacers, terminal boards, motor slot wedges, switchgear barriers and structural insulating plates in electrical equipment.

SafetyCutting, drilling and sanding release glass-fibre and epoxy dust that irritates skin, eyes and lungs, so use extraction and masks. Overheated boards emit brominated fumes; avoid open flame and dispose of scrap properly.

Solder alloy is the general name for low-melting metal alloys, mostly tin-based, that wet and join metal surfaces below about 450 C without melting the parts. Composition decides the melting range, strength and joint reliability, so the alloy is picked for the job.

PropertiesMelting ranges run from approx. 138 C for tin-bismuth to approx. 217-227 C for tin-silver-copper and tin-copper; eutectic compositions melt at a single temperature, and joints give good conductivity and wetting.

ApplicationsPCB assembly, plumbing and sheet-metal joining, wire splicing and lug tinning, heat exchangers; supplied as wire, bar, paste and preforms.

SafetyFlux fumes irritate the airways and can cause occupational asthma, so use fume extraction. Molten solder burns, and workers should wash hands after handling and keep food away from the bench.

Traditional solder of about 60% tin and 40% lead, or the eutectic 63/37 mixture. It melts at a low temperature, wets copper readily and gives bright smooth joints, so it stayed the benchmark until RoHS restrictions pushed most electronics to lead-free alloys.

PropertiesEutectic 63Sn-37Pb melts sharply at approx. 183 C with density approx. 8.4 g/cm3, 60/40 has a short pasty range, wets very well, and forms reliable joints at low process temperature.

ApplicationsHand soldering and repair, exempt military, aerospace and medical electronics, legacy equipment, wire tinning and some radiator repair.

SafetyLead is a cumulative toxin, so wash hands after handling and do not eat or smoke at the bench. Handle dross as hazardous waste, extract flux fumes, and note it is restricted in RoHS products.

These tin-rich alloys replace lead with silver, copper, bismuth or antimony to satisfy RoHS rules. The common SAC305 (96.5Sn-3Ag-0.5Cu) and tin-copper alloys serve reflow and wave soldering, though they need noticeably hotter processing than tin-lead.

PropertiesSAC305 melts at approx. 217-220 C and Sn-0.7Cu at approx. 227 C, density approx. 7.3-7.4 g/cm3, wetting is poorer than tin-lead, joints are harder, and tin whisker growth is a reliability concern.

ApplicationsMass-produced consumer, automotive and telecom electronics in reflow and wave soldering, and lead-free plumbing joints for drinking water lines.

SafetyHigher soldering temperatures create more flux fume and dross and raise burn risk, so use extraction and temperature control. Even without lead, wash hands after handling and manage scrap and flux residues carefully.

A thick paste of fine silver flakes or powder suspended in resin, glass frit or solvent, printed or dispensed and then cured or fired to form conductive layers. It makes electrical connections where soldering is unsuitable, such as on heat-sensitive substrates and solar cells.

PropertiesBulk silver resistivity is approx. 1.6 x 10^-6 ohm-cm and density approx. 10.5 g/cm3; cured pastes are less conductive, and viscosity, cure or firing temperature and adhesion vary by formulation.

ApplicationsFront-side contacts on crystalline silicon solar cells, RFID and printed antennas, membrane switches, die attach in LED and power devices, and EMI shielding.

SafetySolvents and resins are flammable and can irritate skin and airways, so store cool and ventilated. Silver stains skin and is toxic to aquatic life, so keep paste and wash water out of drains.

Very fine wire, commonly 15-50 micrometres in diameter, drawn from 99.99% gold and sometimes lightly doped to control grain size. It is thermosonically welded to connect chip pads to package leads, valued for oxidation resistance and reliable ball bonds.

PropertiesGold density approx. 19.3 g/cm3, melting point approx. 1064 C, resistivity approx. 2.2 x 10^-8 ohm-m, excellent ductility and corrosion resistance, though costly and prone to intermetallic growth with aluminium pads.

ApplicationsChip-to-lead interconnects in IC packages, LEDs, sensors, RF modules and automotive or aerospace electronics requiring high reliability.

SafetyGold itself is non-toxic but valuable, so control and reclaim scrap. The hair-thin wire kinks easily and can pierce skin, and bonding machines have heated stages and ultrasonic tools.

A thin circular slice of single-crystal silicon, cut from a Czochralski or float-zone ingot, then lapped, etched and polished to a mirror finish. It is the substrate on which chips are built, with standard diameters of 150, 200 and 300 mm.

PropertiesA 300 mm wafer is about 775 micrometres thick, flatness and roughness are controlled to nanometre scale, and wafers are p- or n-doped with defined crystal orientation such as (100) or (111).

ApplicationsSubstrate for microprocessors, memory, analog ICs, power devices and MEMS; thinner square-cut variants serve as solar cell wafers.

SafetyWafers are brittle and break into razor-sharp shards, so use vacuum wands or tweezers in cleanrooms. Polishing, etching and cleaning use HF, strong acids and solvents, and grinding dust is respirable.

Thin sheets of alkali-free aluminoborosilicate glass, made by fusion or float processes, form the flat base for display panels, touch sensors, thin-film solar cells and photomasks. Smoothness, dimensional stability and low ion content let thin-film layers be deposited accurately.

PropertiesThickness often 0.3-0.7 mm, density approx. 2.4-2.5 g/cm3, strain point approx. 650-700 C for display grades, low thermal expansion close to silicon, and transparent, smooth and electrically insulating.

ApplicationsTFT-LCD and OLED display panels, touch panels, thin-film solar modules, photomasks, microfluidic chips and emerging glass-core packaging substrates.

SafetyThin sheets chip and shatter into sharp edges, so wear cut-resistant gloves and protect edges. Hydrofluoric acid etching is highly hazardous, and scoring dust is abrasive.

Lithium cobalt oxide (LiCoO2) is a layered oxide cathode, the first commercial lithium-ion cathode, made by firing lithium carbonate with cobalt oxide. It offers high volumetric energy density, so it is used where small size matters more than cost or longevity.

PropertiesPractical capacity approx. 140-150 mAh/g, nominal cell voltage approx. 3.6-3.7 V, density approx. 5.0 g/cm3, moderate cycle life, and limited thermal stability when charged above approx. 4.2 V.

ApplicationsSmartphones, laptops, tablets, cameras and wearables, where compact cells with high energy per volume are needed.

SafetyProne to thermal runaway if overcharged or abused. Cobalt oxide powder is harmful if inhaled and a skin and respiratory sensitiser, so control dust and avoid short circuits, crushing and overvoltage charging.

Lithium iron phosphate (LiFePO4) is an olivine-structured cathode whose strong phosphorus-oxygen bonds hold oxygen tightly, giving excellent thermal stability and long cycle life. It uses abundant iron and no cobalt or nickel, making it a leading choice for EVs and stationary storage.

PropertiesPractical capacity approx. 150-160 mAh/g, nominal cell voltage approx. 3.2 V with a flat discharge curve, density approx. 3.6 g/cm3, thousands of cycles, but lower energy density and weaker cold performance.

ApplicationsEnergy storage systems, electric buses and two-wheelers, passenger EVs, solar home batteries, telecom backup and power tools.

SafetyA safer chemistry, but cells can still vent flammable electrolyte if overcharged, punctured or shorted. Powder dust is an irritant; use a BMS and avoid charging below freezing, which plates lithium.

Lithium nickel manganese cobalt oxide is a layered cathode family written LiNixMnyCozO2, with ratios such as 111, 532, 622 and 811. Raising nickel increases capacity, while manganese and cobalt add structural stability, so makers tune the mix for EVs and power tools.

PropertiesCapacity approx. 160-200 mAh/g depending on nickel content, nominal cell voltage approx. 3.6-3.7 V, density approx. 4.7-4.8 g/cm3, good energy and power balance, with thermal stability falling as nickel rises.

ApplicationsPassenger EV battery packs, e-scooters, e-bikes, power tools, laptop cells and grid storage where energy density is prioritised.

SafetyHigh-nickel cells can release oxygen and enter thermal runaway under abuse, so need a BMS, thermal management and propagation barriers. Nickel and cobalt powders are sensitisers; control dust and keep powder dry.

Lithium nickel cobalt aluminium oxide, typically near LiNi0.8Co0.15Al0.05O2, is a nickel-rich layered cathode in which aluminium stabilises the structure. It gives high specific energy and power and is best known from cylindrical cells used in some electric vehicles.

PropertiesCapacity approx. 190-200 mAh/g, nominal cell voltage approx. 3.6 V, density approx. 4.7 g/cm3, high energy density and good power, but moderate thermal stability and sensitivity to moisture.

ApplicationsCylindrical 18650 and 21700 cells in EV packs, premium power tools, medical devices, and aerospace and satellite battery packs.

SafetyThermal runaway risk is serious in abuse, so packs need monitoring, cell-level protection and spacing. The powder is moisture-sensitive and alkaline, and nickel compounds are sensitisers, so use extraction and respirators.

Lithium manganese oxide (LiMn2O4) has a three-dimensional spinel structure that lets lithium ions move quickly in all directions. It uses low-cost manganese and gives high power and good thermal behaviour, but manganese dissolution limits life, so it is often blended with NMC.

PropertiesCapacity approx. 100-120 mAh/g, nominal cell voltage approx. 3.7-4.0 V, density approx. 4.2 g/cm3, high rate capability and low cost, but capacity fades at elevated temperature.

ApplicationsPower tools, medical instruments, e-bikes, and blended with NMC in some electric vehicle cells such as early Nissan Leaf packs.

SafetyCells are fairly stable but can still overheat if shorted or overcharged. Manganese dust and fume are neurotoxic with chronic exposure, so use extraction and respiratory protection when handling powder.

Graphite is a layered form of carbon whose planes let lithium ions intercalate between them, making it the dominant anode material in lithium-ion cells. Natural flake graphite is spheroidised and coated, while synthetic graphite is made by graphitising petroleum coke above 2500 C, giving uniform quality.

PropertiesTheoretical capacity approx. 372 mAh/g, working potential approx. 0.1 V vs Li/Li+, density approx. 2.2 g/cm3, high electrical and thermal conductivity, and good cycle life, though fast charging risks lithium plating.

ApplicationsAnodes of nearly all EV and consumer lithium-ion cells; also arc furnace electrodes, brake and clutch materials, dry lubricants and pencils.

SafetyFine graphite dust is combustible, electrically conductive and irritating to the lungs, and can short electrical equipment, so control dust. Lithiated graphite in damaged cells reacts violently with water.

Nano-silicon, silicon-oxide (SiOx) or silicon-carbon composites are blended into or replace graphite in the anode to raise capacity, since silicon stores several times more lithium. Silicon swells during charging, so particles are nano-structured, coated or mixed with graphite to limit cracking.

PropertiesTheoretical capacity approx. 3500-4200 mAh/g (about ten times graphite), volume expansion approx. 300% when fully lithiated, lower first-cycle efficiency, and commercial blends usually contain only a few to about 10% silicon.

ApplicationsHigh-energy EV cells, smartphones, wearables, drone batteries and premium cylindrical cells that blend silicon with graphite.

SafetyNano-silicon powder disperses easily, can be combustible, and fine particles are an inhalation concern, so handle under controlled dust conditions. Swelling stresses the cell, so charge limits and pack compression design matter.

Metallic lithium is the lightest metal and the highest-capacity anode material, used as foil in primary lithium batteries and in research and emerging solid-state and lithium-metal cells. Its reactivity and dendrite growth during recharging are the main technical hurdles.

PropertiesDensity approx. 0.53 g/cm3, melting point approx. 180.5 C, theoretical capacity approx. 3860 mAh/g, the lowest electrode potential of any metal, soft, and highly reactive with water and nitrogen.

ApplicationsPrimary lithium coin and cylindrical cells for meters and memory backup, lithium-thionyl chloride cells, laboratory research and prototype solid-state and lithium-sulphur batteries.

SafetyReacts violently with water, releasing hydrogen, and burns with a hot flame, so handle in a dry room or argon glovebox with Class D extinguishers nearby. Dendrites can short cells; lithium burns skin.

Thin electrodeposited or rolled copper sheet, usually 6-12 micrometres thick, serves as the current collector for the graphite anode in lithium-ion cells. Copper tolerates the low anode potential, where aluminium would alloy with lithium, and it must be smooth, clean and uniform to hold the coating.

PropertiesThickness approx. 6-12 micrometres in typical cells, purity at least 99.9%, density approx. 8.9 g/cm3, high conductivity, enough tensile strength and elongation to survive coating and winding, and controlled surface roughness.

ApplicationsAnode current collector in EV, phone and storage lithium-ion cells; also used in flexible printed circuits.

SafetyFoil is very thin, tears and creases easily and has sharp edges, so wear gloves. Metal particles or contamination on the foil can cause internal short circuits, and oils or oxidation weaken coating adhesion.

Thin, high-purity aluminium foil, typically 10-20 micrometres thick, acts as the cathode current collector. Aluminium is stable at high potential because of its protective oxide, light and inexpensive, but it cannot be used at the anode because it alloys with lithium.

PropertiesPurity approx. 99.3% or higher (1xxx series), density approx. 2.7 g/cm3, thickness approx. 10-20 micrometres, good conductivity, light weight, and sometimes carbon-coated to reduce contact resistance.

ApplicationsCathode current collector in lithium-ion cells for EVs, phones and storage; also supercapacitor electrodes and pouch cell laminate layers.

SafetyFoil edges cut fingers and the foil tears easily. Fine aluminium dust and burrs are combustible and can short a cell, so keep slitting areas clean and use clean gloves.

Polyvinylidene fluoride is a semi-crystalline fluoropolymer, dissolved in NMP, that glues active material and carbon onto the current collector. It is chemically stable at high voltage and adheres well, so it is the standard cathode binder, though it needs a hazardous solvent.

PropertiesDensity approx. 1.78 g/cm3, melting point approx. 170 C, electrochemically stable up to about 4.5 V vs Li, good adhesion and mechanical strength, and slight swelling in electrolyte.

ApplicationsCathode slurries (LFP, NMC, NCA), some graphite anodes and ceramic separator coatings; elsewhere used for pipe linings and filtration membranes.

SafetyUsually dissolved in NMP, a reproductive toxin requiring ventilation, gloves and closed mixing with solvent recovery. PVDF itself is stable but releases toxic hydrogen fluoride if heated to very high temperature.

Sodium carboxymethyl cellulose is a water-soluble cellulose derivative used as thickener and binder in aqueous anode slurries, commonly paired with styrene-butadiene rubber (SBR). It controls viscosity and keeps graphite dispersed, replacing solvent processing and lowering cost and environmental burden.

PropertiesWhite powder that forms viscous solutions in water at low concentration, degree of substitution typically 0.7-1.2, stable at anode potentials, but brittle alone, so it is blended with SBR.

ApplicationsWater-based graphite and silicon-graphite anode slurries in lithium-ion cells; non-battery uses include food thickener, toothpaste, detergents and drilling fluids.

SafetyLow toxicity, but the powder clumps in water and fine dust can irritate airways and form combustible dust clouds. Wet spills are slippery, and the powder should be kept dry until mixing.

A thin porous polymer membrane, usually polyethylene or polypropylene or a laminate of both, with pores near 0.1 micrometre, sits between anode and cathode. It blocks electrical contact yet lets lithium ions pass through electrolyte, and some grades add ceramic coating or shutdown behaviour.

PropertiesThickness approx. 7-25 micrometres, porosity approx. 35-50%, strong in tension, wettable by electrolyte, with PE melting and closing pores near approx. 130-135 C and PP near approx. 165 C.

ApplicationsBetween electrodes in all liquid-electrolyte lithium-ion cells for phones, EVs, laptops and storage; coated versions serve high-power and high-safety packs.

SafetyThe film is fragile, and pinholes, contamination or wrinkles cause internal short circuits. It shrinks and melts at high temperature, so use ceramic-coated grades where needed and keep it clean, dry and static-free.

In lithium-ion cells the electrolyte is a solution of lithium salt, usually LiPF6 at about 1 mol/L, in a mixture of cyclic and linear organic carbonates such as EC, DMC and EMC, with small additives. It carries lithium ions between electrodes and helps form the protective SEI layer on graphite.

PropertiesIonic conductivity approx. 8-12 mS/cm at room temperature, linear carbonate solvents with flash points near room temperature, voltage window up to about 4.3-4.5 V, and strong sensitivity to moisture.

ApplicationsFilling of lithium-ion cells for EVs, phones, laptops and storage; formulations are adjusted with additives for fast charge, high voltage or low temperature.

SafetyFlammable and toxic, and it forms HF with moisture, so handle in a dry room with gloves and face shield. Fires need dry powder or CO2 extinguishers, and vapours should be kept from heat.

Lithium hexafluorophosphate is a white crystalline salt that dissolves in carbonate solvents to supply the lithium ions in most commercial lithium-ion cells. It balances conductivity, electrochemical stability and the ability to passivate aluminium, though it is thermally and hydrolytically unstable.

PropertiesDensity approx. 1.5 g/cm3, high ionic conductivity in carbonate mixtures, stable against aluminium corrosion; the solid decomposes near 200 C, solutions degrade at lower temperatures, and it reacts with moisture to form HF.

ApplicationsSolute in lithium-ion electrolytes at around 1 mol/L for EV, consumer and storage cells, and a standard salt in electrolyte research formulations.

SafetyHighly moisture-sensitive; contact with water or humid air forms toxic, corrosive hydrogen fluoride. Handle in a dry room or glovebox with acid-resistant gloves, face shield and respirator, and follow the SDS first-aid steps.

Fine carbon black, acetylene black, Super P, carbon nanotubes or graphene additives are mixed at about 1-3% into electrode coatings. They form conductive networks between poorly conducting active particles, such as LFP, so current can flow through the whole electrode.

PropertiesPrimary particles are tens of nanometres across, with surface area from tens to hundreds of m2/g, low bulk density and good electrical conductivity; carbon nanotube grades form networks at under 1% loading.

ApplicationsCathode and anode slurries in lithium-ion cells, especially LFP, as well as supercapacitors, conductive plastics and antistatic coatings.

SafetyExtremely fine, light powder spreads easily, stains everything, irritates the respiratory tract and forms combustible dust clouds, so use closed transfer, extraction and anti-static controls. Nanotube powders need extra inhalation precautions.

High-quality aluminium alloys, such as 1xxx, 3003 and 6xxx series sheet, extrusions and castings, used for cell cans, tabs, pack enclosures, busbars and cooling plates. The battery-grade label implies tight control of purity, surface cleanliness, flatness and properties for laser welding and sealing.

PropertiesDensity approx. 2.7 g/cm3, thermal conductivity approx. 160-235 W/m-K depending on alloy, good corrosion resistance and formability, light weight, and laser weldable with correct alloy choice.

ApplicationsPrismatic and cylindrical cell casings, EV battery pack trays and cold plates, current-carrying tabs and busbars, and module end plates.

SafetyLaser welding and cutting give metal fume and spatter, and burrs can short cells. Machining swarf and fine dust are combustible, and aluminium fires need Class D agents, not water.

High-purity copper (99.9% or better) in strip, bar and tab form, used for the high-current connections in a battery: nickel-plated tabs, busbars, cell interconnects and cables. It is called battery grade for its high conductivity and tightly controlled surface and impurity levels.

PropertiesConductivity at least 100% IACS, density approx. 8.9 g/cm3, melting point approx. 1085 C, thermal conductivity approx. 390-400 W/m-K, ductile enough to bend tabs, and often tin or nickel plated.

ApplicationsBusbars and interconnects in EV packs, tabs welded to cells, high-current cables and heat spreaders in power batteries.

SafetyA short circuit through a copper busbar can cause an arc and extreme heat instantly, so use insulated tools and covers. Laser or ultrasonic welding of copper gives fume and spatter.

Cement is the finely ground hydraulic powder that reacts with water to set and harden, binding sand and stones into mortar and concrete. The term covers all types, from ordinary Portland to blended and special cements, so the grade and type must always be specified.

PropertiesFine grey powder with specific gravity near 3.15; sets by hydration even under water, gains most strength within 28 days, and releases heat while curing; strength is reported in MPa at 28 days.

ApplicationsBinder in concrete, masonry mortar, plaster, grouts, floor screeds, precast blocks, pipes and tiles on virtually every building and infrastructure site.

SafetyWet cement is alkaline and causes burns and dermatitis, so wear gloves and boots; dry dust irritates eyes and lungs, so use dust masks, and wash splashes off promptly.

Portland cement is made by burning limestone and clay to clinker near 1450 degrees C, then grinding it with a few percent gypsum. In India it is sold as Ordinary Portland Cement, OPC 43 and OPC 53, giving high early strength for structural work.

PropertiesPrincipal compounds are alite and belite; 28-day strength is at least 43 or 53 MPa for OPC 43 and 53; initial setting is not before 30 minutes; high heat of hydration.

ApplicationsReinforced and prestressed concrete, precast elements, high-rise columns, bridges and any work needing fast strength gain or early formwork removal.

SafetyAlkaline, skin-burning when wet; avoid kneeling in fresh concrete. Bag handling creates fine dust containing trace chromium compounds that can sensitise skin, so use gloves and respirators.

Blended cement replaces part of the clinker with industrial by-products such as fly ash or ground granulated blast-furnace slag. Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC) are the common Indian types, trading slower early strength for durability and lower heat.

PropertiesLower heat of hydration, slower early strength but continued gain beyond 28 days, finer pores, better resistance to sulphates and chlorides, and a lower carbon footprint than OPC.

ApplicationsMass concrete, foundations, marine and coastal structures, plastering, masonry and general residential construction where long-term durability outweighs early strength.

SafetyAlkaline like other cements, so protect skin and eyes from wet mix. Fine fly ash and slag dust is irritating to breathe; keep bags dry and avoid dry sweeping.

Concrete is a hardened mixture of cement, water, sand and coarse aggregate, sometimes with admixtures. It is strong in compression and cheap to place in almost any shape, so steel bars are cast inside to carry tension.

PropertiesDensity approx. 2400 kg/m3 for plain concrete; compressive strength graded M20 to M40 and above in IS 456; weak in tension; strength depends on water-cement ratio and curing.

ApplicationsFoundations, slabs, beams, columns, retaining walls, dams, bridge piers, pavements, culverts and precast units such as pipes and kerbstones.

SafetyFresh concrete burns skin through alkalinity and heavy loads strain backs. Cutting or drilling hardened concrete releases crystalline silica dust, so use water suppression and respirators.

Ready-mix concrete is batched at a central plant under controlled proportioning and delivered in transit mixers to site, as covered by IS 4926. Consistency and grade are tested at the plant, which beats site mixing for large pours.

PropertiesMix design and slump are controlled; workability falls with time, so placing must finish within the specified window; grades M20 to M60 are common; cube samples confirm 28-day strength.

ApplicationsHigh-rise slabs and columns, pumped pours, road and airport pavements, and congested urban sites with no room for stockpiles or batching equipment.

SafetyNever add water to a hardening load; keep clear of reversing mixer trucks and pump hose whip. Wash drums and chutes away from drains because the wash water is strongly alkaline.

Mortar is a paste of cement or lime, sand and water used to bed bricks and blocks, plaster surfaces and fill joints. Unlike concrete it has no coarse aggregate, so it is mixed for adhesion and workability, not for bulk strength.

PropertiesCement-sand ratios of about 1:3 to 1:6 are typical; bond, workability and water retention matter more than strength; weaker mixes accommodate small movements without cracking.

ApplicationsLaying brick and block walls, internal and external plastering, pointing, flooring bed under tiles, and repairing masonry joints.

SafetyCement-based mortar is alkaline and burns skin during long plastering shifts, so wear gloves and eye protection. Sand screening and dry mixing generate dust containing silica.

Brick here means burnt clay brick, moulded from clay, dried and fired in a kiln at roughly 900 to 1000 degrees C. It is the traditional Indian masonry unit, valued for fire resistance, durability and easy local manufacture.

PropertiesDensity approx. 1.6 to 1.9 g/cm3; modular size 190 x 90 x 90 mm; compressive strength by class, from about 3.5 MPa upward in IS 1077; water absorption limited to about 20 percent.

ApplicationsLoad-bearing and partition walls, boundary walls, arches, chimneys, paving and flooring, and as aggregate when over-burnt bricks are crushed.

SafetyHandling causes abrasion and hand injuries; stacks can collapse. Cutting generates silica-bearing dust, and kiln work involves high heat and smoke, so ventilation and masks are needed.

Autoclaved aerated concrete block is made from cement, lime, fly ash or sand and aluminium powder, which creates tiny gas bubbles before steam curing in an autoclave. The result is a light, cellular block that is easy to cut and thermally insulating.

PropertiesDensity approx. 0.5 to 0.7 g/cm3, about one third of clay brick; compressive strength about 3 to 4.5 MPa; good thermal insulation and fire resistance; absorbs water if unprotected.

ApplicationsNon-load-bearing infill walls and partitions in framed multi-storey buildings, and external walls where reduced dead load and thermal comfort are wanted.

SafetyCutting and chasing produces fine alkaline dust containing silica, so wet-cut or use extraction and respirators. Thin-bed adhesive is cementitious and irritates skin.

Fly ash brick is formed under pressure from fly ash collected at thermal power stations, mixed with lime or cement and sand or stone dust, then cured instead of fired. Its manufacture is covered by IS 12894 and it reduces clay mining and kiln emissions.

PropertiesDensity approx. 1.7 to 1.9 g/cm3; uniform size with smooth faces; strength gain continues with moist curing; low water absorption and smaller mortar need than hand-moulded clay bricks.

ApplicationsLoad-bearing and infill walls, boundary walls and low-rise housing, particularly near power plants where fly ash is available at low cost.

SafetyDry fly ash is a fine respirable dust, and lime or cement in the mix is alkaline. Wear masks and gloves while mixing, and cure and stack bricks on level ground.

Sand is loose, naturally occurring granular rock, mostly quartz, collected from riverbeds or pits and washed. Here it is considered as a raw natural material in bulk, whereas fine aggregate is the graded form specified for concrete.

PropertiesParticle size from about 0.075 to 4.75 mm; specific gravity approx. 2.6; moisture content makes volume change (bulking) of damp sand; silt and clay content must stay low.

ApplicationsPlastering and masonry mortar, filling and levelling under floors, bedding for paving blocks and pipes, and mould-making in foundries after suitable preparation.

SafetyDry sand dust contains respirable crystalline silica, so wet it down and wear dust masks. Deep sand excavations and heaped stockpiles can collapse, so avoid undercutting them.

Fine aggregate is the sand-sized fraction passing a 4.75 mm sieve, graded into Zones I to IV under IS 383. It may be natural river sand, crushed stone sand, also called manufactured sand, or a blend, chosen to fill voids between coarse particles.

PropertiesGraded by sieve analysis, with fineness modulus roughly 2.2 to 3.2; specific gravity approx. 2.6; clean, with limited silt, clay, organic matter and chlorides.

ApplicationsFine fraction in structural concrete mixes, ready-mix plants, cement mortar and plaster, and block and paver manufacture where grading controls strength and finish.

SafetyManufactured sand dust is respirable and contains silica, so use water sprays and masks at crushing plants. Check that washed material is not left sludgy underfoot.

Coarse aggregate is the portion of concrete aggregate retained on a 4.75 mm sieve, normally in nominal sizes of 10, 20 or 40 mm. It forms the stone skeleton that carries load, so its strength, shape and cleanliness govern concrete behaviour.

PropertiesSize above 4.75 mm; specific gravity approx. 2.6 to 2.9; limits on flakiness, elongation, crushing and impact values; angular, clean and well-graded particles give better strength.

ApplicationsStructural concrete for beams, slabs and columns, pavement quality concrete, precast units, and as a base layer under roads and railway ballast beds.

SafetyHeavy loads strain backs and stockpiles can slide; crushing and screening create silica dust and noise. Wear masks, hearing protection and safety footwear around loaders.

Gravel consists of rounded pebbles and stones, mostly 4.75 to 75 mm, formed by water action in rivers and deposits. Its smooth shape gives good workability in concrete but weaker bond than angular crushed rock.

PropertiesRounded, smooth particles; drains freely; lower interlock and mechanical bond than crushed stone; natural deposits vary in cleanliness, and may include clay or soft pieces.

ApplicationsDrainage layers, pipe bedding, garden and driveway surfacing, filter media beneath foundations and concrete where river gravel is the locally available aggregate.

SafetyLoose gravel is a slip and ankle-twist hazard on slopes and ramps. Digging pits risks collapse, so batter or support the sides, and cover the face of any trench.

Crushed stone is rock from quarries that has been blasted and broken in jaw and cone crushers, then screened to size. Its angular, rough faces interlock well and bond tightly with cement paste or bitumen, which is why roads prefer it.

PropertiesAngular particles with rough texture; strength depends on parent rock, often granite, basalt or limestone; produced in controlled sizes such as 6, 10, 20 and 40 mm.

ApplicationsConcrete aggregate, road sub-base and base courses, bituminous mixes, railway ballast, retaining-wall backfill and gabion filling.

SafetyQuarry blasting, crushers and dust expose workers to noise and silica, so use water suppression, hearing protection and masks. Keep clear of unstable quarry faces and moving loaders.

Limestone is a sedimentary rock made mostly of calcium carbonate, formed from marine shells and sediments. It is quarried as building stone and aggregate, and it is the main raw material for making cement and lime, so it underpins much of the construction industry.

PropertiesDensity approx. 2.3 to 2.7 g/cm3; fizzes with dilute acids; moderate hardness, easily cut and polished; calcines at around 900 degrees C into quicklime.

ApplicationsCement clinker raw material, lime production, flux in steelmaking, road aggregate, flooring tiles, and flue-gas desulphurisation sorbent in power plants.

SafetyCutting and grinding produce dust that irritates lungs. Burning to quicklime brings caustic burns and heat, and acid contact releases carbon dioxide, so avoid confined spaces.

Marble is metamorphic rock formed when limestone recrystallises under heat and pressure, giving interlocking calcite crystals and the characteristic veins. It is polished to a high gloss and chosen mainly for appearance, particularly in interiors.

PropertiesDensity approx. 2.6 to 2.7 g/cm3; Mohs hardness about 3 to 4; takes a high polish; stained and etched by acids including lemon juice and many cleaners.

ApplicationsFlooring, wall cladding, stair treads, countertops, monuments and sculpture, with Rajasthan, Makrana among the best-known Indian sources.

SafetyPolished marble floors are slippery when wet. Slab handling needs lifting aids to avoid crush injuries, and wet cutting limits dust; avoid acidic cleaners that damage the surface.

Granite is a coarse-grained igneous rock composed chiefly of quartz, feldspar and mica. It is very hard and resists weathering and abrasion, so it serves in demanding structural, paving and decorative uses, often outlasting the buildings it clads.

PropertiesDensity approx. 2.6 to 2.8 g/cm3; compressive strength typically over 100 MPa; Mohs hardness about 6 to 7; very low water absorption; polishes well.

ApplicationsKitchen countertops, kerbstones, paving, building facades, steps, foundations, bridge piers and crushed aggregate for concrete and roads.

SafetySawing and polishing release crystalline silica dust linked to silicosis, so use wet cutting, extraction and respirators. Slabs are heavy, so use clamps or vacuum lifters.

Slate is a fine-grained metamorphic rock derived from shale or mudstone that splits cleanly along cleavage planes into thin flat sheets. This natural splitting and low water absorption make it a long-lived roofing and paving material.

PropertiesDensity approx. 2.7 to 2.8 g/cm3; low porosity and water absorption; splits into thin plates; resists frost and most chemicals; brittle and may delaminate over time.

ApplicationsRoofing tiles, flooring and wall cladding, damp-proof courses, billiard table beds, laboratory benchtops and old-style electrical switchboard panels.

SafetySplit edges are razor-sharp and slabs fall easily from roofs; wear cut-resistant gloves and fall protection. Cutting produces silica-bearing dust, so cut wet.

Gypsum is the soft mineral calcium sulphate dihydrate, mined or recovered as a by-product from flue-gas desulphurisation. Heating drives off part of its water to make plaster, and a small amount is ground into cement to control setting.

PropertiesMohs hardness about 2, so scratched by a fingernail; density approx. 2.3 g/cm3; loses chemically bound water on heating; slightly soluble in water and not suitable for wet exposure.

ApplicationsRaw material for plaster of Paris and wall putty, plasterboard, cement retarder at a few percent, soil conditioner and sulphate source in fertilisers.

SafetyDust irritates eyes, nose and throat, so use masks when crushing or sanding. Calcining at about 150 degrees C involves hot equipment, and bags must be kept dry.

Plaster of Paris is calcium sulphate hemihydrate, produced by gently heating gypsum. Mixed with water it sets quickly into a smooth, hard solid that reproduces fine detail and can be shaped easily before it fully hardens.

PropertiesSets in minutes, usually within 10 to 30 minutes depending on mix; expands slightly on setting, giving sharp casts; light, fire-resistant, but weak when wet and soluble.

ApplicationsFalse ceilings, cornices and decorative mouldings, medical casts and splints, ceramic and foundry moulds, patching cracks, and statue and idol making.

SafetySetting plaster gives off heat, so never wrap a limb in thick wet plaster. Dust irritates lungs, and wash residue into a trap, not the drain, where it hardens.

Bitumen is the dark, sticky hydrocarbon residue left after vacuum distillation of crude oil. Indian road work specifies it by viscosity grade such as VG-10, VG-30 or VG-40 under IS 73, and it acts as the waterproof binder that holds aggregate together.

PropertiesDensity approx. 1.01 to 1.04 g/cm3; thermoplastic and softens when heated; waterproof; adhesive; graded by viscosity or penetration, with mixing carried out around 150 to 170 degrees C.

ApplicationsBinder in road surfacing and asphalt mixes, waterproofing of roofs and foundations, bituminous paints and emulsions, roofing felts and pipe coatings.

SafetyHeated bitumen at over 150 degrees C causes deep, sticking burns, so wear heat-resistant gloves and face shields. Keep water away from hot tanks because it can boil over, and fumes are irritating.

In Indian practice asphalt is the paving mix made by combining graded aggregate, filler and bitumen, usually hot. Different from bare bitumen, it is the finished material that is laid and rolled into flexible road pavement.

PropertiesCompacted density approx. 2.2 to 2.4 g/cm3; flexible, so it tolerates traffic loads; stiffness depends on temperature; durability depends on bitumen content, aggregate grading and compaction.

ApplicationsHighway and urban road wearing courses, bituminous concrete layers, airport runways, parking areas, bridge deck overlays and waterproof mastic flooring.

SafetyFreshly laid hot mix at 130 to 160 degrees C causes burns and heat stress, and fumes irritate lungs. Keep pedestrians and workers clear of rollers, pavers and tippers.

Rebar is ribbed steel bar embedded in concrete to resist tensile and shear forces. In India, thermo-mechanically treated bars in grades Fe 500, Fe 500D and Fe 550D are common under IS 1786, with a hard outer skin and a tougher ductile core.

PropertiesDensity approx. 7.85 g/cm3; Fe 500 has minimum yield strength of 500 MPa; D grades guarantee higher elongation and ductility; ribs improve bond; weldability depends on carbon equivalent.

ApplicationsReinforcement in beams, slabs, columns, footings, retaining walls and bridge decks, and in precast concrete elements and earthquake-resistant frames.

SafetyCut ends and tying wire cause lacerations and impalement hazards, so cap projecting bars. Bundles are heavy, so use lifting gear, and cutting or welding throws sparks and fumes.

Structural steel is rolled steel in sections such as I-beams, angles, channels, plates and hollow tubes, used for load-bearing frames. In India, IS 2062 grades like E250 and E350 are widely used, joined by bolting or welding.

PropertiesDensity approx. 7.85 g/cm3; elastic modulus about 200 GPa; E250 yield strength is at least 250 MPa; ductile, weldable, and equally strong in tension and compression.

ApplicationsIndustrial sheds, high-rise frames, bridges, transmission towers, crane gantries, storage tanks, pressure vessel supports and warehouse mezzanines.

SafetyWelding and gas cutting produce fumes, arc flash and burns, so use shields, ventilation and fire watch. Erection involves falls from height and dropped loads, so use harnesses and certified lifting gear.

Plywood is a board made by gluing thin wood veneers in layers with the grain of adjacent plies at right angles. This cross-lamination gives good strength in both directions and reduces warping, and the board is available in large flat sheets.

PropertiesDensity approx. 0.5 to 0.7 g/cm3; strong along both axes; moisture-resistant types use phenolic glue; IS 303 grades include MR and BWR, and IS 710 covers marine plywood.

ApplicationsFurniture and cabinets, wall panels, doors, formwork for concrete, flooring underlay, packing cases, vehicle bodies and boat building.

SafetySawing and sanding create wood dust, and glue lines can release formaldehyde, so use dust extraction and ventilation. Large sheets are awkward to carry, and edges splinter hands.

Medium density fibreboard is made by breaking wood into fine fibres, mixing them with resin and pressing the mat under heat into uniform sheets. Its smooth, dense, grain-free surface machines cleanly and takes paint and laminate well.

PropertiesDensity approx. 0.6 to 0.8 g/cm3; uniform and flat; edges can be routed to profile; poor screw-holding on edges; swells irreversibly with moisture unless a moisture-resistant grade is used.

ApplicationsPainted furniture panels, kitchen cabinet doors, shelving, mouldings, speaker enclosures, display units and substrate for laminates or veneers.

SafetyCutting creates very fine dust that penetrates deep into lungs, and the resin may emit formaldehyde. Use extraction, FFP masks and sealed edges, and keep panels dry.

Particle board is made by bonding wood chips, shavings and sawdust with resin under heat and pressure. It is the least expensive of the common wood panels, and is suited to indoor furniture that will be laminated and stay dry.

PropertiesDensity approx. 0.6 to 0.75 g/cm3; coarser, weaker and heavier than plywood for a given strength; screw-holding is moderate; edges crumble and moisture causes swelling.

ApplicationsLow-cost wardrobes, office desks, kitchen carcasses, shelving and partitions with laminate or melamine facing, mainly in dry indoor settings.

SafetyMachining releases dust and resin binders can emit formaldehyde, so extract dust and ventilate rooms. Panels are heavy and edges chip, so use gloves when handling.

A flux-coated mild steel stick electrode, such as AWS E6013, whose coating is rich in titanium dioxide (rutile). It strikes easily, runs smoothly in all positions and leaves an easily removed slag, which makes it popular for light fabrication and for beginners.

PropertiesE6013 weld metal has about 415 MPa minimum tensile strength, runs on AC or DC, gives moderate penetration and a smooth bead, and its slag lifts easily, but hydrogen control is weaker than basic types.

ApplicationsSheet and light structural fabrication, gates, grills, furniture, general repair, and welding of mild steel plate up to a few millimetres thick.

SafetyArc and spatter burn, so use a shade 10-12 helmet, leather gloves and apron. Fumes contain manganese and fluorides, and chipping slag throws hot fragments, so ventilate and wear safety glasses.

Low-hydrogen electrodes, such as E7018, carry a coating of calcium carbonate and fluoride (lime-fluorspar). They deposit tough weld metal with very little hydrogen, so they are specified for thick sections, high-strength steels and restrained joints at risk of cracking.

PropertiesE7018 weld metal has approx. 480 MPa minimum tensile strength with good low-temperature toughness and low hydrogen; it runs on DC electrode positive or AC, needs baking, and leaves heavier slag.

ApplicationsPressure vessels, boilers, pipelines, bridges, structural steel, shipbuilding and heavy machinery welding in critical thick sections.

SafetyThe coating picks up moisture, which causes hydrogen cracking, so bake and hold rods in a heated oven per the maker's instructions; hot rods and ovens burn. Fumes contain fluorides and manganese, so use extraction.

Cellulose-coated rods such as E6010 and E6011 contain a large share of organic material that burns in the arc, producing a strong gas shield and a forceful, deeply penetrating arc. The thin slag and digging action make them traditional for pipeline root passes and dirty steel.

PropertiesE6010 has approx. 415 MPa minimum tensile strength, deep penetration, a fast-freezing pool for vertical-down work and high hydrogen content; E6010 needs DC electrode positive while E6011 also runs on AC.

ApplicationsRoot and hot passes in field pipelines, tank and structural repair on rusty or painted steel, and vertical-down welding of sheet.

SafetyHigh hydrogen content risks cracking in thick or high-strength steel. Do not over-dry the rods, and expect heavy fume and spatter, so ventilate and wear a face shield and flame-resistant clothing.

Coated rods whose core wire or coating supplies chromium and nickel, such as E308L, E309L and E316L for austenitic stainless steel. Matching the filler to the parent grade gives weld metal of similar corrosion resistance, and E309L is used to join stainless to carbon steel.

PropertiesE308L and E316L deposits have approx. 520 MPa minimum tensile strength as welded, low-carbon L grades resist sensitisation, small ferrite content prevents hot cracking, and fully austenitic metal is non-magnetic.

ApplicationsFood, dairy, chemical and pharmaceutical tanks and piping, kitchen equipment, repair of stainless castings, and dissimilar joints using E309L.

SafetyFumes contain hexavalent chromium and nickel, which are carcinogenic, so use local exhaust and respiratory protection. Keep rods dry and use dedicated stainless brushes to avoid carbon steel contamination.

Continuous solid wire on spools, such as ER70S-6 for mild steel, fed automatically into a GMAW torch under shielding gas. The wire acts as both electrode and filler and carries deoxidisers like silicon and manganese, giving fast welds with little cleaning.

PropertiesER70S-6 gives weld metal tensile strength around 480 MPa, diameters commonly 0.8-1.6 mm, copper coating aids feeding and contact, deoxidisers tolerate light mill scale, and spatter is modest with correct gas.

ApplicationsAutomotive body and chassis welding, structural fabrication, robotic welding lines, agricultural equipment and workshop work; aluminium and stainless use matching wires.

SafetyArc radiation requires a helmet and covered skin, and gas cylinders must be chained upright. Fume contains manganese and iron oxides and the arc makes ozone, so ensure extraction; trim wire ends, which are sharp.

Straight cut rods, typically 1-3.2 mm in diameter and 1 m long, are hand-fed into the pool of a tungsten arc in GTAW. Because arc heat is independent of the filler, welders get precise control and clean welds on thin sections and on stainless, aluminium and titanium.

PropertiesCommon classes include ER70S-2 for steel, ER308L for stainless and ER4043 or ER5356 for aluminium; rods are uncoated, chemistry controlled and bright-finished, and strength depends on the alloy.

ApplicationsRoot passes on pipes, food-grade and pharmaceutical piping, aerospace and motorsport tubing, aluminium fabrication and thin stainless sheet.

SafetyKeep rods clean and handle with clean gloves. Rod ends are sharp, the arc gives strong UV and ozone, and argon can displace oxygen in confined spaces, so ventilate.

A tubular wire with a metal sheath filled with flux and alloy powders, run with or without external shielding gas. The core provides arc stabilisers, slag and deoxidisers, so it deposits quickly and handles outdoor wind and thick sections better than solid MIG wire.

PropertiesGas-shielded E71T-1 gives weld metal of approx. 480 MPa minimum tensile strength, self-shielded types such as E71T-11 need no gas, deposition rates are high, slag covers the bead, and diameters are commonly 1.2-2.4 mm.

ApplicationsShipbuilding, structural steel erection, heavy equipment, bridge construction, outdoor site welding in wind, and hardfacing overlays on worn parts.

SafetyProduces more fume and slag than solid wire, and the fume contains manganese and fluorides, so use extraction or a respirator. Hot slag and spatter burn, and the flux core absorbs moisture if stored damp.

Solid or metal-cored wire, such as EM12K or EH14, is fed under a blanket of granular flux so the arc is hidden. Wire and flux are chosen as a pair to reach the required strength and toughness, and the process deposits metal very rapidly at high current.

PropertiesDiameters typically 2.4-4.8 mm, with 3.2 and 4.0 mm common, deposition far higher than manual welding, weld strength depends on the wire and flux combination, and the bead is smooth and spatter-free.

ApplicationsLong seams on pressure vessels, boilers, pipes, wind towers, ship hull panels and heavy beams, mostly in the flat or horizontal position.

SafetyAlmost fumeless, but hot flux and slag cause burns and flux dust irritates. Hoppers and flux handling create dust, coils are heavy, and the high-current equipment carries electrical hazards.

Wear-resistant welding consumables, such as high-chromium cast iron, cobalt-based stellites, nickel-based alloys and tungsten carbide types, deposited as overlays on worn or new parts. A thin hard layer protects cheaper base metal against abrasion, impact, heat or corrosion.

PropertiesHardness ranges from approx. 40 HRC for martensitic types to above 60 HRC for chromium carbide deposits; carbide-rich overlays resist abrasion well, but heavy deposits often show stress-relief cracks.

ApplicationsExcavator teeth and bucket edges, crusher hammers, mixer blades, valve seats, shear blades, drilling tools and sugar mill and cement plant parts.

SafetyCobalt, chromium and nickel in fumes are hazardous, so use extraction and respirators. Hard deposits can crack unless preheated, grinding gives hot sparks and dust, and hot workpieces cause burns.

Filler metals that melt above 450 C yet below the base metal are drawn by capillary action into close-fitting joints without melting the parts. Families include copper-phosphorus, aluminium-silicon, nickel and copper types, chosen for base metals, service temperature and joint clearance.

PropertiesLiquidus is above 450 C by definition, joint gaps of about 0.05-0.15 mm give capillary flow, joints are strong and leak-tight, and flux or a protective atmosphere is needed to clean and wet the surfaces.

ApplicationsHVAC refrigerant tube joints, heat exchangers, carbide tool tipping, automotive radiators, and aerospace honeycomb and jet engine components.

SafetyHeated flux and filler give off fumes, and old cadmium-bearing alloys are highly toxic and must be avoided, so use extraction. Torch brazing involves flammable fuel gas and hot parts.

Brazing filler containing about 2-60% silver with copper, zinc and sometimes tin or nickel, melting between roughly 600 and 800 C. The alloys flow readily at relatively low temperature, wet steel, copper, brass and stainless, and make ductile joints, though silver raises cost.

PropertiesMelting ranges approx. 600-870 C depending on composition, excellent wetting and flow, good electrical conductivity, ductile joints, and cadmium-free grades are now standard.

ApplicationsElectrical contacts and switchgear joints, refrigeration and air-conditioning, jewellery, food-grade equipment, cutlery, carbide tools and stainless steel.

SafetyOlder alloys contained cadmium, whose fumes are extremely toxic, so use cadmium-free grades and check the SDS. Zinc and flux fumes irritate the airways; ventilate, avoid overheating and keep a fire watch.

Copper-zinc alloy rods, typically about 60% copper and 40% zinc, often with tin, nickel, silicon or manganese, used in braze welding (bronze welding) of steel, cast iron and copper. The filler melts at about 870-900 C and does not fuse the parent metal.

PropertiesMelting range approx. 870-900 C, density approx. 8.4 g/cm3, deposit tensile strength typically 350-450 MPa, flows well when flux-coated, but zinc evaporates at high heat, causing fume and porosity.

ApplicationsBraze welding of cast iron repairs, steel tubing and bicycle frames, galvanised sheet, and joining copper to steel in workshop repair.

SafetyZinc oxide fume causes metal fume fever when overheated, so work with ventilation or extraction and avoid overheating the pool. Use oxy-fuel gear safely with flashback arrestors; flux coatings contain borates.

Copper-based alloys with tin, aluminium, silicon or phosphorus, including phosphor bronze, silicon bronze (ERCuSi-A) and aluminium bronze fillers. They are used when a weld must resist corrosion and wear, or when joining dissimilar metals at lower heat input than steel welding.

PropertiesSilicon bronze fillers melt around 1000 C with deposit tensile strength roughly 250-350 MPa, phosphor and aluminium bronzes give stronger, harder deposits, and all offer good seawater and wear resistance.

ApplicationsWelding galvanised sheet in auto bodywork, repair of bearings, bushings, marine propellers and valve bodies, and joining copper to steel.

SafetyCopper-alloy fumes irritate the eyes and respiratory tract, so use local extraction, especially indoors. Aluminium-bronze arc work gives intense fume and ozone, and hot deposits and spatter burn.

Non-metallic mineral mixtures, containing silicates, fluorides, oxides and carbonates, protect the weld pool, stabilise the arc and form slag. Granular fluxes serve submerged arc welding, while paste or powder fluxes such as borax help brazing and soldering.

PropertiesFused or agglomerated granules of about 0.2-2 mm, classed as acidic, neutral or basic by basicity index; basic fluxes give cleaner, tougher welds, and all types must be kept dry.

ApplicationsSubmerged arc welding of plate and pipe seams, electroslag welding, electrode coatings and flux-cored wire cores, and brazing and soldering fluxes.

SafetyFlux absorbs moisture, causing porosity and hydrogen cracking, so store it sealed and dry it per supplier advice. Dust and fluoride fumes irritate; wear a dust mask and gloves.

Argon, carbon dioxide, helium and their mixtures are fed to the torch to shield the molten pool from oxygen and nitrogen in air. Pure argon is used for TIG and non-ferrous metals, while argon-CO2 mixes such as 80/20 suit mild steel MIG welding.

PropertiesArgon is inert and heavier than air, CO2 gives deep penetration but more spatter, helium raises heat input, and typical torch flow is about 10-20 L/min.

ApplicationsArgon for TIG welding of stainless steel and aluminium, Ar-CO2 for MIG welding of structural steel, CO2 for economical steel welding, and Ar-He or Ar-O2 for specialist work.

SafetyInert gases displace oxygen and, being heavier than air, collect in tanks, pits and confined spaces, causing asphyxiation without warning. Chain cylinders upright, use regulators with caps, and ventilate.

Fuel gas, usually acetylene (or LPG, propane, propylene), burned with oxygen in a torch for cutting, heating, brazing and gas welding. Acetylene-oxygen gives the hottest flame at about 3100 C, while LPG gives a cooler flame favoured for cutting thick steel and heating.

PropertiesOxy-acetylene flame reaches approx. 3100-3200 C and oxy-propane approx. 2800 C; acetylene is lighter than air, is unstable above about 1 bar (15 psi) gauge, and a neutral flame has near equal gas volumes.

ApplicationsSteel cutting and scrapping, preheating before welding, straightening and heating for bending, brazing, and gas welding of thin steel sheet and pipe.

SafetyAcetylene is dissolved in acetone in cylinders, which must stay upright, and it must never be used above about 1.5 bar. Fit flashback arrestors, check hoses, and keep oil and grease away from oxygen fittings.

Mineral oil is a lubricant base stock refined from crude petroleum, then blended with additives for specific duties. It is the most widely used and cheapest lubricating oil, performing well in ordinary temperatures and moderate loads.

PropertiesSold in ISO viscosity grades; viscosity falls as temperature rises; moderate viscosity index; oxidises faster above about 70 to 90 degrees C; pour point limits cold-weather flow.

ApplicationsMachine tool slideways, general bearings and gearboxes, engine oils in older or less demanding engines, hydraulic circuits and chain lubrication.

SafetyProlonged skin contact causes dermatitis, so wear nitrile gloves. Spills make floors slippery, oil mist is irritating, and used oil must go to authorised recyclers, never drains.

Synthetic oil uses chemically engineered base fluids such as polyalphaolefins, esters or polyglycols, not refined crude. Its uniform molecules give stable viscosity, good low-temperature flow and long life, at a higher purchase price than mineral oils.

PropertiesHigh viscosity index, often above 130 for PAO types; flows at very low temperatures; resists oxidation at higher temperatures; longer drain intervals; seal and paint compatibility must be checked.

ApplicationsTurbocharged and high-performance engines, aircraft and wind-turbine gearboxes, screw compressors, and equipment operating in extreme cold or heat.

SafetyPolyglycol and ester types can swell seals and soften paints, and PAG must not be mixed with mineral oils. Wear gloves, avoid slips on spills and follow the data sheet.

Semi-synthetic oil, often called synthetic blend, combines mineral base oil with a portion of synthetic base stock plus additives. It aims for better temperature behaviour and oxidation resistance than mineral oil while costing less than a full synthetic.

PropertiesPerformance and price sit between mineral and fully synthetic oil; better cold flow and thermal stability than mineral; synthetic fraction varies by maker and is not standardised.

ApplicationsPassenger car and two-wheeler engines, light commercial vehicles, and industrial gearboxes where operators want longer life than mineral oil without full synthetic expense.

SafetyHandle like other engine oils: gloves to prevent dermatitis, drip trays against slippery spills, and recycling of drained oil. Never mix blends with incompatible products without checking the data sheet.

Hydraulic oil is the working fluid in pumps, cylinders and valves, transmitting power through pressure while lubricating moving parts. Quality grades carry anti-wear, anti-foam and rust inhibitors, and the oil must remain clean because dirt damages precision valves.

PropertiesCommon grades ISO VG 32, 46 and 68; HM types contain anti-wear additives; nearly incompressible; stable viscosity across temperature; good air release, demulsibility and filterability.

ApplicationsExcavators, presses, injection moulding machines, machine tool hydraulics, forklifts, lifts, tippers and steering or brake systems of heavy equipment.

SafetyPinhole leaks at high pressure can inject oil under the skin, so never check leaks by hand. Hot oil scalds, and sprayed mist can ignite near hot surfaces.

Gear oil is a high-viscosity lubricant with extreme-pressure additives that protect gear teeth under sliding and shock loading. Automotive grades are classified by API GL rating and SAE grade, while industrial grades use ISO VG numbers.

PropertiesThicker than engine oil, commonly ISO VG 150 to 460 in industrial gearboxes; sulphur-phosphorus EP additives form protective films; some GL-5 types attack yellow metals in synchronisers.

ApplicationsVehicle differentials and manual transmissions, industrial gear reducers, worm gearboxes, steel mill drives, conveyors, cranes and winches.

SafetyEP additives have a strong sulphur smell and irritate skin; use gloves. Drain gearboxes only after cooling, because hot oil burns, and clean spills promptly to prevent slips.

Compressor oil is formulated to lubricate and seal cylinders and rotors in air or gas compressors while resisting the high heat of compression. It has strong oxidation stability and low volatility, so that varnish and carbon deposits stay minimal.

PropertiesTypical ISO VG 46, 68 or 100; high flash point, low carry-over and carbon-forming tendency; good water separation; synthetic types extend drain intervals in screw compressors.

ApplicationsReciprocating air compressors, rotary screw compressors, vane compressors, vacuum pumps and refrigeration units with the specified oil type.

SafetyOil carbon deposits in hot discharge lines can ignite or explode, so use the correct grade and change intervals. Oil mist irritates, and never use compressed air to clean skin.

Turbine oil is a highly refined rust-and-oxidation-inhibited oil designed for steam and gas turbines, where it lubricates bearings, cools them and sometimes acts as governor control fluid. It must work for years without breaking down or forming sludge.

PropertiesMostly ISO VG 32 or 46; superb oxidation stability; separates quickly from water; resists foaming; low sludge and varnish tendency; high viscosity index for stable film thickness.

ApplicationsSteam and gas turbine bearings, hydroelectric generators, large circulating systems, power plant auxiliaries and sometimes centrifugal compressors and paper machines.

SafetyPressurised lube lines near hot turbine casings are a serious fire risk if they leak, so inspect fittings and insulation. Oil on floors is slippery; test oil condition regularly.

Refined mineral oil, usually naphthenic or paraffinic, fills transformers to insulate live parts and carry heat from the core and windings to the radiators. Dielectric strength and viscosity are tested routinely, and ester or silicone fluids replace it where fire safety matters.

PropertiesFresh dry oil has high breakdown voltage across a 2.5 mm gap, flash point approx. 140 C or above, density below approx. 0.89 g/cm3, low viscosity and a low pour point.

ApplicationsPower and distribution transformers, reactors, circuit breakers, bushings and instrument transformers for insulation and cooling.

SafetyFlammable, so keep ignition sources away and provide fire protection around oil-filled equipment. Moisture and dissolved gases reduce dielectric strength; very old oil may contain PCBs, so test before handling, and prevent spills reaching drains.

Cutting oil, also called neat or straight cutting oil, is a mineral or synthetic oil with sulphur, chlorine or fatty additives, used undiluted in machining. It lubricates better than water-based coolants, which suits slow, heavy or difficult cuts.

PropertiesExcellent lubricity and corrosion protection; poor cooling relative to water-based fluids; viscosity chosen by operation; EP additives help in tapping, broaching and gear cutting; may stain copper alloys.

ApplicationsTapping, threading, broaching, deep hole drilling, gear hobbing, automatic lathes and honing of tough steels where tool life matters more than cooling.

SafetyHot chips and fast cuts can ignite mist or smoke, and oil mist harms lungs, so use enclosures and extraction. Skin contact causes dermatitis, and floors become slippery.

Soluble cutting fluid is a concentrate of oil, emulsifiers and additives that mixes with water to form a milky emulsion. Water gives excellent cooling while the oil phase gives lubrication, making it the usual economical choice for general machining.

PropertiesMixed with water at roughly 3 to 10 percent, depending on duty; strong cooling; concentration and pH need regular checking; prone to bacterial growth and tank rancidity if neglected.

ApplicationsTurning, milling, drilling and grinding on lathes and CNC machines, particularly for steels and cast iron in general engineering workshops.

SafetyDermatitis from repeated contact and mist inhalation are the main hazards, so wear gloves and use mist collectors. Stale emulsion smells and carries bacteria; dispose of it as waste.

Metalworking fluid is the umbrella term for coolants and lubricants applied to cutting, grinding, forming and rolling. It covers straight oils, soluble oils, semi-synthetic and fully synthetic fluids, each balanced between lubrication, cooling, corrosion protection and cleanliness.

PropertiesSelected by operation, material, machine type and water quality; key control points are concentration, pH, tramp oil, hardness and microbial level; synthetics are clearer but lubricate less.

ApplicationsMachining centres, grinders, stamping and drawing presses, wire drawing, rolling mills and central coolant systems serving many machines.

SafetyMist and splashes cause skin and respiratory problems, so use enclosures and gloves. Biocides are chemicals themselves, so handle per the supplier's safety data sheet; used fluid needs treatment.

Grease is a semi-solid lubricant formed by dispersing a thickener, often a metal soap, in lubricating oil with additives. It stays in place where oil would drain, seals out contaminants and releases oil gradually under load.

PropertiesClassified by NLGI consistency number, 000 to 6, with 2 most common; defined by base oil viscosity, thickener type and dropping point; water resistance and load capacity vary widely.

ApplicationsRolling and plain bearings, wheel hubs, chassis points, open gears, motor bearings, couplings, pins and bushes of construction machinery.

SafetyHigh-pressure grease guns can inject grease through skin, requiring urgent medical care. Over-greasing overheats bearings, mixing incompatible greases softens them, and spilled grease creates slips.

Lithium grease is thickened with lithium soap, typically lithium 12-hydroxystearate, giving a smooth, versatile multi-purpose grease. Lithium complex versions raise the temperature limit, and both are widely used because they handle water, load and mixed duties reasonably well.

PropertiesDropping point about 180 to 200 degrees C for simple lithium and higher for complex; continuous service to roughly 120 degrees C; good water resistance and mechanical stability; NLGI 2 is typical.

ApplicationsAutomotive wheel bearings, chassis, electric motor bearings, agricultural machinery, pumps and general plant lubrication points.

SafetyGrease guns can inject product under the skin, so never point at hands. Wipe spills, avoid mixing with incompatible thickeners, and do not over-pack high-speed bearings.

Calcium grease uses a calcium soap thickener and is valued for its excellent water resistance and low cost. Conventional types contain a little water to stabilise the soap, so they suit only low-temperature service, typically in wet, slow-moving applications.

PropertiesWater-washout resistant and adhesive; service limited to about 60 to 80 degrees C because stabilising water is lost; smooth buttery texture; poor high-temperature performance.

ApplicationsWater pumps, marine fittings, chassis points, agricultural implements, open-air machinery, cup greasing and low-speed plain bearings exposed to moisture.

SafetyOverheating dries out and ruins the grease, so avoid use in hot bearings. Beware grease-gun injection injuries, and clean up spills since greased surfaces are slippery.

Molybdenum disulfide grease is a base grease, often lithium, loaded with a few percent of fine MoS2 powder. This layered solid lubricant stays between surfaces when the oil film is squeezed out, giving protection under shock and heavy load.

PropertiesExcellent extreme-pressure and anti-scuff behaviour; MoS2 itself works well above ordinary grease temperatures; dark grey or black; less suited to very high-speed rolling bearings.

ApplicationsConstant-velocity joints, heavy-duty pins and bushings, slow-moving highly loaded bearings, splines, press slides and mining or construction machine joints.

SafetyStains skin and clothing, and powder is irritating, so use gloves and wash well. Avoid contact with food or high-speed precision bearings, and watch for grease-gun injection hazards.

Silicone grease is made by thickening silicone oil with fumed silica or PTFE. It is chemically inert, water-repellent and stable over a wide temperature range, but carries load poorly compared with petroleum-based greases on steel surfaces.

PropertiesUseful roughly from -50 to 200 degrees C; electrical insulator; compatible with most rubbers and plastics; resists water, ozone and oxidation; limited load-carrying capacity.

ApplicationsO-rings and seals, vacuum fittings, valve stems, electrical connectors and spark-plug boots, plastic gears and sliding parts, and food-grade or laboratory glassware joints.

SafetySilicone contamination spoils paint and adhesive bonds, so keep it out of paint shops. Surfaces become very slippery, and overheated silicone can give off irritating fumes.

Heat transfer oil, also called thermic fluid, is a thermally stable oil circulated in closed loops to carry heat from a heater to process equipment at low pressure. It avoids the high pressure needed by steam at the same temperature.

PropertiesMineral types commonly operate up to around 300 degrees C bulk temperature; high flash and fire points; low vapour pressure; oxidation and cracking raise viscosity and carbon over time.

ApplicationsThermic fluid heaters in textile, chemical, plywood press, food frying, rubber and plastics plants, and asphalt tank heating.

SafetyLeaks at 200 to 300 degrees C cause severe burns and fires, especially on insulation. Remove moisture before heating to avoid violent steam release, and test oil regularly.

Rust preventive oil is a thin, oily film of mineral oil or solvent-thinned carrier with corrosion inhibitors, applied to protect bare steel surfaces. It excludes moisture and neutralises traces of contaminants during storage, shipping and between machining stages.

PropertiesForms thin, water-displacing or waxy films; protection time varies from weeks to months by type; may be removed with solvent or alkaline washers, and some types are compatible with engine oil.

ApplicationsProtecting finished machine parts, tools, bearings, sheet steel coils, moulds and dies, fasteners and engine components during storage or export packing.

SafetySolvent-thinned types are flammable and release vapours, so ventilate and avoid ignition sources. Slippery film on floors and prolonged skin contact are issues; wear gloves.

Hardwood comes from broadleaved flowering trees such as teak, oak, sal, beech and maple. The term is botanical, not a measure of hardness, but most species are dense, durable and attractive, with finer grain than the common conifer timbers.

PropertiesDensity usually about 0.5 to 1.2 g/cm3; generally stronger and more wear-resistant than softwood; slower growing and more expensive; usually dried slowly to avoid cracking.

ApplicationsQuality furniture, flooring, doors, window frames, tool handles, railway sleepers, boat building, veneers and musical instruments.

SafetyHardwood dust is a recognised cause of nasal cancer and sensitisation, so use extraction and respirators. Hard timber also dulls tools and encourages kickback during machining.

Softwood is timber from coniferous trees such as pine, fir, spruce and deodar. These species grow quickly and are cheap and light, so they dominate framing, packaging and general carpentry despite lower durability and strength than most hardwoods.

PropertiesDensity typically about 0.35 to 0.6 g/cm3; easy to cut and nail; resinous; lower decay and wear resistance than most hardwoods unless treated; high strength-to-weight ratio.

ApplicationsRoof trusses, wall framing, scaffolding planks, pallets, crates, shuttering boards, pulp and paper, and economical furniture.

SafetyResin and preservative-treated timber can irritate skin, and dust may sensitise lungs. Treated offcuts should not be burned, and heavy stacks should be strapped.

Teak is the golden-brown timber of Tectona grandis, long grown in Indian forests and plantations. Natural oils and silica make it unusually resistant to decay, termites and weathering, so it keeps stable dimensions in damp or outdoor conditions.

PropertiesDensity approx. 0.6 to 0.7 g/cm3; low shrinkage and good dimensional stability; natural oils resist rot and insects; moderate hardness; easy to work and polish.

ApplicationsDoor and window frames, high-quality furniture, ship decks and boats, outdoor benches, panelling and laboratory benchtops.

SafetyTeak dust can cause dermatitis, eye and breathing irritation in sensitive people. Oils may foul glue joints, so wipe with solvent first, and always use dust extraction.

Oak is a strong, heavy hardwood from Quercus species, easily recognised by its prominent grain and medullary rays. It is hard-wearing and takes stain well, and white oak is notably resistant to liquid penetration, which is why it is used for barrels.

PropertiesDensity approx. 0.65 to 0.75 g/cm3; tough and hard; ring-porous with open grain; rich in tannins; durable when heartwood is used, but may stain with wet iron.

ApplicationsHardwood flooring, staircases, quality furniture, wine and spirit barrels, beams in timber framing, railway sleepers and general joinery.

SafetyOak dust is classified as carcinogenic with long exposure, so use extraction and masks. Tannins corrode ordinary steel fasteners in damp conditions, so use stainless steel or galvanised fixings.

Pine is a softwood from Pinus species that is straight-grained, light and easy to work. It is among the cheapest and most widely stocked timbers, which suits construction, joinery and packaging where heavy loads are not expected.

PropertiesDensity approx. 0.35 to 0.6 g/cm3 depending on species; pale colour; knots are common; resin pockets may bleed through paint; accepts preservative treatment and nails well.

ApplicationsBuilding framing, wall panelling, pallets and packing crates, interior doors, low-cost furniture, foundry pattern making and concrete shuttering.

SafetyResin and turpentine can irritate skin and burn readily, so keep heat sources away. Sawdust may sensitise airways, and knots can throw splinters during machining.

Beech is a pale, fine-grained hardwood from Fagus species. It is hard, heavy and shock-resistant, and it bends well after steaming, so it is favoured for workshop furniture and handles, but it is not durable outdoors.

PropertiesDensity approx. 0.7 to 0.75 g/cm3; uniform texture; high strength and wear resistance; steam bends well; moves noticeably with humidity; low decay resistance unless treated.

ApplicationsWoodworking workbenches, hand-plane bodies, tool handles, bentwood chairs, children's toys, kitchen utensils and school furniture.

SafetyBeech dust can trigger asthma and skin reactions and should be extracted at source. Steam-bending involves hot, wet timber and heavy clamping forces, so wear heat-resistant gloves.

Maple is a hard, pale, close-grained hardwood from Acer species, especially hard or sugar maple. Its tough, smooth surface resists abrasion and denting, so it is used where wear is high and a clean appearance is wanted.

PropertiesDensity for hard maple about 0.63 to 0.70 g/cm3; high hardness and wear resistance; fine uniform grain; burns easily during machining; poor outdoor durability.

ApplicationsGym and dance floors, bowling lanes, butcher blocks, workbench tops, furniture, violin backs and drum shells.

SafetyHard maple scorches and kicks back if cutters are blunt, so keep blades sharp. Dust irritates lungs and skin, and requires extraction and respirators.

Bamboo is a fast-growing grass whose hollow, jointed culms mature in a few years. Along the fibre it is strong and light, and processed into strips and laminates it serves as a renewable alternative to timber.

PropertiesDensity approx. 0.6 to 0.9 g/cm3; high tensile strength along the fibre; hollow culms with nodes; shrinks on drying; untreated bamboo is attacked by borers and fungi.

ApplicationsBuilding scaffolding, rural housing, laminated flooring and boards, furniture, handicrafts, paper pulp and reinforcement in composites.

SafetySplit bamboo has razor-sharp edges and splinters, so wear gloves. Boron preservatives need careful handling, and bamboo scaffolding must be tied and inspected to avoid falls.

Plywood is a board made by gluing thin wood veneers in layers with the grain of adjacent plies at right angles. This cross-lamination gives good strength in both directions and reduces warping, and the board is available in large flat sheets.

PropertiesDensity approx. 0.5 to 0.7 g/cm3; strong along both axes; moisture-resistant types use phenolic glue; IS 303 grades include MR and BWR, and IS 710 covers marine plywood.

ApplicationsFurniture and cabinets, wall panels, doors, formwork for concrete, flooring underlay, packing cases, vehicle bodies and boat building.

SafetySawing and sanding create wood dust, and glue lines can release formaldehyde, so use dust extraction and ventilation. Large sheets are awkward to carry, and edges splinter hands.

Veneer is a very thin sheet of wood, typically 0.2 to 3 mm thick, peeled from a log or sliced from a flitch. It spreads valuable decorative timber over a cheaper core and forms the plies in plywood.

PropertiesThin, flexible and highly figured; rotary-cut or sliced; splits easily along grain; must be pressed and glued to a stable substrate; can be sanded through easily.

ApplicationsDecorative faces for plywood, MDF and doors, furniture panels, musical instruments, marquetry, and plies for plywood manufacture.

SafetyThin sheets have sharp edges that cut skin, and sanding generates fine dust. Glues and finishing solvents need ventilation, and stacks of veneer offcuts are a fire load.

Medium density fibreboard is made by breaking wood into fine fibres, mixing them with resin and pressing the mat under heat into uniform sheets. Its smooth, dense, grain-free surface machines cleanly and takes paint and laminate well.

PropertiesDensity approx. 0.6 to 0.8 g/cm3; uniform and flat; edges can be routed to profile; poor screw-holding on edges; swells irreversibly with moisture unless a moisture-resistant grade is used.

ApplicationsPainted furniture panels, kitchen cabinet doors, shelving, mouldings, speaker enclosures, display units and substrate for laminates or veneers.

SafetyCutting creates very fine dust that penetrates deep into lungs, and the resin may emit formaldehyde. Use extraction, FFP masks and sealed edges, and keep panels dry.

Particle board is made by bonding wood chips, shavings and sawdust with resin under heat and pressure. It is the least expensive of the common wood panels, and is suited to indoor furniture that will be laminated and stay dry.

PropertiesDensity approx. 0.6 to 0.75 g/cm3; coarser, weaker and heavier than plywood for a given strength; screw-holding is moderate; edges crumble and moisture causes swelling.

ApplicationsLow-cost wardrobes, office desks, kitchen carcasses, shelving and partitions with laminate or melamine facing, mainly in dry indoor settings.

SafetyMachining releases dust and resin binders can emit formaldehyde, so extract dust and ventilate rooms. Panels are heavy and edges chip, so use gloves when handling.

Cork is the lightweight bark of the cork oak, Quercus suber, harvested every several years without felling the tree. Its closed cells filled with air and coated in suberin make it compressible, springy, waterproof and a poor heat conductor.

PropertiesDensity approx. 0.12 to 0.25 g/cm3; elastic recovery after compression; low thermal conductivity; good vibration and sound damping; resists many liquids; burns slowly and smoulders.

ApplicationsBottle stoppers, gaskets, expansion joints, floor and wall insulation, vibration pads, bulletin boards and shoe insoles.

SafetyCork dust is combustible and can smoulder, so keep ignition sources away. Dust from sanding irritates lungs, and mouldy stored cork can trigger allergic lung reactions.

Natural fibre is a general term for fibres taken from plants, animals or minerals, with plant types such as jute, flax, hemp and cotton most relevant to engineers. They are renewable and biodegradable, increasingly used as reinforcement in composites.

PropertiesLower density than glass fibre; good specific strength; absorb moisture; properties vary with crop and processing; typically degrade when heated much above 200 degrees C.

ApplicationsRopes, textiles, geotextiles, packaging, sound-absorbing panels, automotive interior door and trim parts, and bio-composites with polymer matrices.

SafetyFibre dust can cause lung irritation and is combustible, and damp bales may heat or grow mould. Resin handling during composite lay-up needs gloves and ventilation.

Jute is a long, coarse bast fibre taken from the stem of Corchorus plants, grown mainly in the Ganges delta of eastern India and Bangladesh. It is cheap, strong in tension and biodegradable, but stiff and sensitive to wet conditions.

PropertiesDensity approx. 1.3 to 1.5 g/cm3; high tensile stiffness with low elongation; rot-prone when wet; ligno-cellulosic; absorbs moisture readily; coarse texture.

ApplicationsGunny sacks, hessian cloth, carpet backing, ropes, geotextile nets for erosion control, and fibre reinforcement for polymer composites.

SafetyDry jute burns readily and godown stacks are a fire risk. Processing creates dust and fibre fragments that irritate lungs and skin, and wet bales can mould.

Cotton fibre is the soft seed hair of Gossypium plants, made of nearly pure cellulose. It spins into soft, absorbent yarn and is also used as wiping waste, filler and reinforcement in some industrial laminates.

PropertiesDensity approx. 1.5 g/cm3; highly absorbent; good strength, improved when wet; withstands moderate heat but chars; biodegradable; cellulose content around 90 percent or more.

ApplicationsTextiles, industrial wiping rags and waste, filter cloth, wicks, hoses and belts reinforcement, and cotton-phenolic laminates for gears and bearings.

SafetyCotton dust in mills can cause byssinosis, so control it with ventilation. Oily cotton waste can self-heat and ignite, so store used rags in closed metal bins.

Flax fibre is a bast fibre extracted from the stems of Linum usitatissimum by retting and scutching, and spun into linen. Among plant fibres it offers high stiffness and strength for its weight, so it is popular in biocomposites.

PropertiesDensity approx. 1.4 to 1.5 g/cm3; high specific strength and stiffness among natural fibres; low elongation; absorbs moisture, which affects bonding with resins; biodegradable.

ApplicationsLinen fabric, ropes and twine, composite panels for automotive interiors, sports goods, bio-based laminates and insulation mats.

SafetyScutching and carding dust irritates lungs, and dry flax is flammable. Epoxy or other resins used in composites need gloves, ventilation and an eye wash within reach.

A class of metals that return to a remembered shape when heated or unloaded after deformation, through a reversible martensite-austenite transformation. Nickel-titanium is the dominant type, with copper-based alloys as cheaper alternatives. The class is wider than the single alloy Nitinol.

PropertiesNiTi types recover strains of up to about 6-8%; transformation temperature is set by composition and heat treatment; copper-based alloys are cheaper but have lower fatigue life and recoverable strain.

ApplicationsThermal actuators and valves, pipe couplings, eyeglass frames, orthodontic wires, vascular stents, robotic actuators, and fire damper triggers.

SafetyActuating parts become hot enough to burn, and cycling causes fatigue fracture. Nickel-containing alloys can trigger allergy, and copper-alloy fumes from hot work need ventilation.

The specific, near-equiatomic nickel-titanium alloy that gave shape memory alloys their prominence, developed at the Naval Ordnance Laboratory. Besides shape memory it shows superelasticity at body temperature, which makes it vital in minimally invasive medical devices.

PropertiesRoughly 55 wt% nickel and 45% titanium; density approx. 6.45 g/cm3; melting range approx. 1,240-1,310 °C; recoverable strain up to approx. 8%; good corrosion resistance and biocompatibility.

ApplicationsSelf-expanding stents, guidewires, orthodontic archwires, eyeglass frames, medical retrieval baskets, thermostatic valves, and aerospace couplings.

SafetyNickel is a sensitiser and fine dust is a suspected carcinogen. Titanium swarf can ignite when ground, and the alloy is difficult to weld or machine, so use proper coolant and fire precautions.

Nickel-, cobalt- or iron-nickel-based alloys designed to hold strength, creep resistance and oxidation resistance at very high temperature. They are strengthened by gamma-prime precipitates or solid solution and are often investment cast or forged for hot sections of engines.

PropertiesRetain useful strength to roughly 800-1,100 °C depending on alloy; density approx. 8-9 g/cm3; excellent creep, fatigue and corrosion resistance but costly, work-hardening and difficult to machine.

ApplicationsGas turbine blades and discs, jet engine combustors, rocket engine parts, nuclear and chemical plant components, and exhaust valves.

SafetyMachining generates hot work-hardened chips and fumes containing nickel, cobalt and chromium, so use extraction and controlled coolant. Welding and grinding need respirators; follow supplier data sheets.

An ultra-high-strength steel with very low carbon, typically 18% nickel plus cobalt, molybdenum and titanium. It is first machined in a soft martensitic state, then age hardened at about 480 °C, so it gains strength with little distortion and with good toughness.

PropertiesYield strength approx. 1,400-2,400 MPa depending on grade (18Ni 200 to 350); density approx. 8.0 g/cm3; good fracture toughness and weldability for its strength, with hardening by a simple ageing treatment.

ApplicationsAerospace landing gear and rocket motor cases, tooling and die-casting dies, high-performance gears and shafts, firearm barrels, and centrifuge rotors.

SafetyNickel and cobalt dust and fumes from grinding or welding are hazardous, so use extraction and respirators. Aged parts are very hard and may be brittle, and ageing furnaces run hot.

A tool steel alloyed with tungsten, molybdenum, vanadium and chromium (grades such as M2 and T1) that stays hard when a cutting edge gets hot. It is tough enough to withstand interrupted cuts, so it is chosen for drills, taps and complex-shaped cutters.

PropertiesHardness approx. 62-67 HRC after heat treatment; retains hardness to about 600 °C (red hardness); density approx. 8.1-8.2 g/cm3; tougher but less wear resistant than cemented carbide.

ApplicationsTwist drills, taps, reamers, milling cutters, broaches, gear hobs, saw blades and punches in machine shops.

SafetySparks and dust from grinding contain tungsten, molybdenum and vanadium, so wear eye protection and use extraction. Hardened tools chip and can shatter if abused; heat treatment involves salt baths and furnaces.

The ISO and European term (often written hardmetal) for sintered composites of very hard carbide grains in a tough metal binder, mainly tungsten carbide with cobalt. It means the same family as cemented carbide, but is also the name used in grade classification systems such as ISO 513 cutting groups.

PropertiesDensity approx. 11-15 g/cm3 depending on carbide mix and binder; hardness approx. 1,300-2,000 HV; very high compressive strength and stiffness; toughness rises with cobalt content while wear resistance falls.

ApplicationsCutting inserts for turning and milling, mining and drilling bits, wear parts, wire-drawing dies, punch and die tooling, and metal forming rolls.

SafetyGrinding dust containing cobalt and tungsten carbide can cause occupational lung disease (hard metal disease) and sensitisation, so use wet grinding, extraction and respirators. Chips from brittle inserts are sharp.

A powder metallurgy product in which hard carbide grains, mostly tungsten carbide, are liquid-phase sintered with a metallic binder, usually 3-25% cobalt. The binder content and grain size are tuned to balance hardness against toughness for each application.

PropertiesDensity approx. 14-15.6 g/cm3 for WC-Co grades; hardness roughly 1,300-2,000 HV; compressive strength in the thousands of MPa; low thermal expansion and high stiffness, with modest tensile toughness.

ApplicationsMetal-cutting tips and inserts, rock drill buttons, stamping dies, extrusion tooling, roll rings, and wear-resistant nozzles and seals.

SafetyCobalt-bearing dust from grinding or EDM is a respiratory sensitiser and suspected carcinogen, so use extraction and respirators. Inserts are brittle; use proper clamping and guards to avoid flying fragments.

The chemical compound WC, a very hard, dense grey ceramic-like substance made by heating tungsten and carbon. Pure WC is rarely used alone, because it is brittle; it is mixed with cobalt to form the cemented carbides, or applied as coatings.

PropertiesDensity approx. 15.6 g/cm3; melting point approx. 2,870 °C; hardness near 9 on the Mohs scale; high stiffness and good thermal conductivity, but brittle without a metallic binder.

ApplicationsCarbide powder for tool and wear parts, thermal-spray wear coatings, hardfacing rods on drilling tools, ball-point pen balls, and abrasive tooling.

SafetyFine tungsten carbide powder and dust are respiratory irritants, particularly when mixed with cobalt. Avoid dry grinding, use extraction, and keep powder away from ignition sources in thermal spray work.

A composite of ceramic particles bonded in a metal matrix. In machining, it nearly always means titanium carbide or carbonitride cermet with nickel or cobalt binder, a distinct alternative to tungsten carbide that gives smooth finishes on steels.

PropertiesDensity approx. 5-7 g/cm3, much lighter than WC-Co; high hot hardness and low chemical wear with steel; lower toughness and thermal shock resistance than cemented carbide.

ApplicationsFinishing and semi-finishing inserts for steel and cast iron, knife blades, sealing rings, valve parts, and wear-resistant coatings.

SafetyGrinding dust contains nickel and cobalt, which are sensitisers, so use extraction and respirators. Inserts chip rather than deform, so avoid interrupted heavy cuts and wear eye protection.

A single atom-thick sheet of carbon atoms arranged in a hexagonal lattice, produced by exfoliation, chemical vapour deposition or reduction of graphene oxide. Commercial products are often multi-layer nanoplatelets, whose properties fall short of the ideal single sheet.

PropertiesIdeal sheet tensile strength about 130 GPa with modulus near 1 TPa; very high electrical and thermal conductivity; real-world flakes vary widely in quality; impermeable to most gases when intact.

ApplicationsConductive inks and coatings, composite additives, battery and supercapacitor electrodes, heat-spreading films, sensors, and anti-corrosion paints.

SafetyDry nanoplatelet powder can become airborne and inhaled, so handle in fume hoods or enclosures with respiratory protection. Toxicity data are still evolving; follow supplier guidance and prevent environmental release.

Cylindrical tubes of rolled graphene sheet only nanometres wide, produced as single-wall (SWCNT) or multi-wall (MWCNT) forms by arc discharge or chemical vapour deposition. They offer exceptional strength and electrical or thermal conductivity per unit weight.

PropertiesIndividual tubes have been measured with tensile strengths in the tens of GPa and modulus around 1 TPa; diameter approx. 1-50 nm; conductivity depends on tube structure; bulk composites deliver far less.

ApplicationsConductive additives in lithium-ion battery electrodes and plastics, composite reinforcement, electrostatic-dissipative coatings, field-emission sources, and sensors.

SafetyAirborne nanotubes, especially long rigid multi-wall types, may cause lung effects similar to fibres, so handle in enclosed or HEPA-filtered systems with respirators. Avoid dry powder spills and follow data sheets.

A cellular metal, typically aluminium, containing a large volume fraction of gas pores formed by foaming the melt with agents such as titanium hydride or by powder-metal routes. It gives low density with high energy absorption and stiffness per weight.

PropertiesClosed-cell aluminium foam density approx. 0.2-0.8 g/cm3 with porosity of 75-90%; crushes at a near-constant plateau stress, absorbing impact energy; good sound damping and low thermal conductivity relative to solid metal.

ApplicationsCrash energy absorbers in vehicles, lightweight stiff panels, sound and vibration damping, heat exchangers, and bone implant scaffolds.

SafetyCut edges are sharp and open-cell foam can trap fluids and corrosives. Aluminium dust and fines from machining are combustible, and manufacture with hydride foaming agents involves hot molten metal and hydrogen release.

A synthetic solid in which the liquid of a gel is replaced by gas, usually via supercritical drying, leaving a nanoporous skeleton of silica or carbon. It is the lightest and best-insulating solid known, though it is fragile unless made into blankets.

PropertiesDensity approx. 0.01-0.15 g/cm3 for silica aerogel with porosity up to about 99%; thermal conductivity approx. 0.013-0.020 W/m·K, lower than still air; hydrophobic grades repel liquid water.

ApplicationsInsulation blankets for oil and gas pipelines, spacecraft and Mars rover insulation, building and cryogenic insulation, particle detectors, and oil-spill absorbents.

SafetySilica aerogel dust irritates skin, eyes and lungs and dries the skin. Wear gloves, safety glasses and a respirator when cutting or handling, and use vacuum, not compressed air, for cleanup.

A substance that stores and releases large amounts of latent heat when it melts or freezes at a nearly constant temperature. Common choices are paraffin waxes, fatty acids and salt hydrates, selected so the melting point matches the target temperature.

PropertiesParaffin types store latent heat of approx. 200 kJ/kg, with melting temperature chosen by composition; thermal conductivity is low, salt hydrates may supercool, and volume changes on melting.

ApplicationsThermal buffering in buildings, cold-chain packaging, battery thermal management, electronics cooling, solar heat storage and thermal-comfort clothing.

SafetyParaffins are flammable, and molten PCM can scald. Salt hydrates may corrode metals, and leaking capsules need containment; check compatibility with enclosure materials and fire rating.

The general class of materials that respond strongly to magnetic fields, divided into soft types that magnetise and demagnetise easily, such as silicon steel, nickel-iron alloys and soft ferrites, and hard types that retain magnetism. Soft materials form transformer and motor cores.

PropertiesSoft materials are rated by high permeability, low coercivity and low core loss; iron has a Curie temperature of about 770 °C; silicon steel laminations cut eddy current losses compared with solid iron.

ApplicationsTransformer and motor cores, inductors and chokes, magnetic shielding, relay armatures, electromagnets, and magnetic recording heads.

SafetyStrong fields can interfere with pacemakers and electronics. Fine iron or ferrite dust may burn, laminations have sharp burrs, and eddy current heating can overheat cores in strong alternating fields.

Hard magnetic materials with high coercivity that hold their magnetisation without power, mainly alnico, ferrite, samarium-cobalt and neodymium-iron-boron. They are compared by remanence, coercivity and maximum energy product, plus temperature limits, corrosion behaviour and cost.

PropertiesMaximum energy product approx. 10-40 kJ/m3 for ferrite, 120-240 for samarium cobalt and 200-400 for neodymium; alnico has high temperature stability but low coercivity; each type has a distinct maximum operating temperature.

ApplicationsElectric motors and generators, loudspeakers, sensors, magnetic separators, MRI systems, holding magnets, and clutches and couplings.

SafetyLarge magnets can crush fingers and affect pacemakers and magnetic media. Rare-earth types are brittle and grinding dust is flammable; keep away from heat that demagnetises them.

A sintered or bonded rare-earth magnet based on the compound Nd2Fe14B, the strongest commercially available permanent magnet. It allows compact motors and holding devices, but it corrodes without a coating and loses strength when hot.

PropertiesMaximum energy product approx. 200-400 kJ/m3 (N35 to N52); density approx. 7.5 g/cm3; maximum working temperature from about 80 °C to 200 °C by grade; Curie temperature approx. 310-400 °C.

ApplicationsElectric vehicle and wind turbine motors, hard disk voice-coil actuators, MRI systems, magnetic couplings, speakers, sensors and lifting magnets.

SafetyStrong attraction causes pinching injuries and can shatter brittle magnets. Keep away from pacemakers, cards and electronics, and avoid heat above rated limits; grinding dust and swarf can ignite.

A ceramic permanent magnet, usually strontium or barium hexaferrite, made by pressing and sintering iron oxide with the carbonate. It is cheap, does not corrode and is electrically insulating, though noticeably weaker than rare-earth magnets.

PropertiesDensity approx. 4.8-5.0 g/cm3; maximum energy product approx. 10-40 kJ/m3; Curie temperature near 450 °C; good corrosion resistance and high coercivity but brittle.

ApplicationsRefrigerator and door magnets, loudspeakers, small DC motors, magnetic separators, toys, and automotive sensors and wiper motors.

SafetyBrittle magnets chip into sharp fragments, so handle carefully with eye protection. Keep away from pacemakers and magnetic media; grinding dust should not be inhaled.

A material that generates electric charge when stressed and deforms when a voltage is applied. Common types are lead zirconate titanate (PZT) ceramics, quartz crystal and polyvinylidene fluoride (PVDF) polymer, chosen by sensitivity and temperature.

PropertiesPZT piezoelectric charge constants span roughly 200-600 pC/N depending on grade; Curie temperature typically approx. 150-350 °C, above which polarisation is lost; quartz offers excellent frequency stability.

ApplicationsUltrasonic transducers and cleaners, fuel injectors, buzzers, accelerometers, quartz clocks, sonar, medical ultrasound probes, and spark igniters.

SafetyPZT contains lead, so avoid dust and follow disposal rules. Heating beyond Curie temperature destroys performance; strained elements may produce high voltage shocks, and discharge them before handling.

A layer placed between a heat-producing component and a heat sink to displace air in microscopic gaps. Forms include greases, gap pads, phase-change films, thermal adhesives, graphite sheets and liquid-metal alloys, chosen by conductivity and reworkability.

PropertiesTypical thermal conductivity approx. 1-10 W/m·K for greases and pads, with liquid metals higher; air is only about 0.026 W/m·K; bond-line thickness and contact pressure strongly affect results.

ApplicationsCPU and GPU heat sinks, power transistor and IGBT module mounting, LED boards, battery packs, telecom electronics, and automotive control units.

SafetyGallium-based liquid metals can short circuit and corrode aluminium, and silicone oils can bleed and contaminate. Keep away from contacts, wipe off excess, and check compatibility and electrical rating.