Materials domain
Composite materials
What composites are made of and how each kind is made: polymer, metal, ceramic and carbon matrices, the fibres and particles that reinforce them, the interphases between, and the routes from hand lay-up to chemical vapour infiltration — every statement tied to the source that makes it.
A composite is two or more materials that stay distinct in the finished part — usually a reinforcement that carries load and a matrix that holds, loads and protects it. Unlike the minerals and refined materials elsewhere on Lithoen, a composite is assembled rather than separated, and that is why it has its own entity types here.[1, 2]
Matrix and reinforcement are roles, not kinds of material. Silicon carbide is the matrix of a SiC/SiC composite and the reinforcement of a particle-reinforced aluminium; carbon is both fibre and matrix in a carbon–carbon composite. Lithoen records the role on the link between composite and constituent, and records the interphase — the coating between fibre and matrix that much of a composite’s toughness depends on — as a third role.[1, 2, 3, 4]
The matrix also decides the manufacturing route, because in each family it reaches the reinforcement in a different state: a liquid resin for polymers, molten or powdered metal for metal matrices, a gas, a polymer precursor or a reacting melt for ceramics and carbon. The routes here are general kinds of process; which one suits a part, and what limits it, is recorded as a sourced claim on each.[1, 2, 3, 4]
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What a composite material is
A composite is two or more materials that stay two in the finished part: a reinforcement that carries the load, a matrix that holds it, and an interface between them that decides how well the pair works together. Its matrix — polymer, metal, ceramic or carbon — names the family.
Fibres and resins of polymer-matrix composites
Glass, carbon, aramid and plant fibres, held in thermosetting or thermoplastic resins. Which fibre sets most of what the part can carry; which kind of resin sets most of how the part can be made.
How polymer-matrix composites are made
From a brush and a bucket of resin to an autoclave: the open-mould, continuous, liquid-moulding, compound-moulding and prepreg routes, what each one does to fibre and resin, and what limits it.
Metal-matrix composites and how they are made
A metal or alloy carrying ceramic particles, whiskers or fibres. The routes are named for the state the metal is in — molten, powdered or vapour — and each fights the same problem: getting a ceramic to sit evenly in a metal that does not want to wet it.
Ceramic-matrix and carbon–carbon composites and how they are made
The routes in this article grow a ceramic or carbon matrix inside a fibre preform — from a gas, from a polymer precursor, or from a molten metal that reacts as it soaks in. Each trades speed against damage to the fibres the matrix is meant to protect.
The four families
Composites are named by their matrix. The root class spans all four and so names no single matrix, reinforcement or route of its own.
Composite material
Composite material
A material made by combining two or more constituents that keep their own identity in the product, usually a reinforcement carried in a continuous matrix. The class spans polymer, metal, ceramic and carbon matrices, so it has no single matrix or route of its own.
Composite material
Polymer-matrix composite
A composite whose matrix is a polymer resin, most often reinforced with glass, carbon, aramid or plant fibres. Its matrix may be a thermoset or a thermoplastic, and which it is largely decides how the part can be made.
Composite material
Metal-matrix composite
A composite whose matrix is a metal or alloy, reinforced with ceramic or other particles, whiskers or fibres; for aircraft, sources name aluminium, magnesium and titanium matrices as the common ones. Its routes are grouped by the state the matrix is in while the composite is formed.
Composite material
Ceramic-matrix composite
A composite whose matrix is a technical ceramic, reinforced with fibres, whiskers or particles. Its reinforcement exists chiefly to toughen a brittle matrix, which is why the fibre–matrix interface and its interphase coatings matter so much.
Composite material
Carbon–carbon composite
A composite of carbon fibres in a carbon matrix, with a pyrolytic carbon interface. It keeps or improves its mechanical properties to very high temperatures but begins to oxidise above about 500 °C.
Polymer-matrix composites by fibre
The same polymer matrices carrying the four fibres that dominate practice; which fibre largely sets what the part can carry.
Composite material
Glass-fibre-reinforced polymer
A polymer-matrix composite reinforced with glass fibres, in either a thermoset or a thermoplastic matrix. Glass is the lower-cost structural fibre, which is why it dominates large structures and consumer products.
Composite material
Carbon-fibre-reinforced polymer
A polymer-matrix composite reinforced with carbon fibres, in a thermoset matrix such as epoxy or a thermoplastic such as polypropylene. Which manufacturing processes are in use depends heavily on which of the two the matrix is.
Composite material
Aramid-fibre-reinforced polymer
A polymer-matrix composite reinforced with aramid fibres, one of the four fibre types most used in fibre-reinforced polymers. Its fibre is tough and impact-resistant but weak in compression and absorbs moisture.
Composite material
Natural-fibre-reinforced polymer
A polymer-matrix composite reinforced with natural fibres, in practice plant fibres such as flax, hemp or jute. Because most plant fibres degrade above about 200 °C, the fibre limits which matrices and processes can be used.
Narrower metal and ceramic classes
Two well-documented members of the metal- and ceramic-matrix families, each with its own constituents and routes.
Composite material
Aluminium-matrix composite
A metal-matrix composite with an aluminium-alloy matrix, typically reinforced with ceramic particles such as silicon carbide or alumina. Stir casting is the route sources describe as the most widely used for it.
Composite material
Silicon-carbide-fibre-reinforced silicon carbide
A ceramic-matrix composite of silicon carbide fibres in a silicon carbide matrix, with an interphase coating on the fibres. Made by combinations of chemical vapour infiltration and melt infiltration, it is the CMC sources describe entering commercial civil aviation.
Reinforcing fibres
Fibres that carry load in one or more families. Carbon fibre appears in all four.
Engineering material
Glass fibre
Fibre drawn from glass, in electrical grades such as borosilicate E-glass and stronger structural grades such as S-glass. It is the lowest-cost of the main structural reinforcing fibres.
Engineering material
Carbon fibre
Fibre consisting mostly of carbon, made chiefly from a polyacrylonitrile precursor by oxidative stabilisation and carbonisation. Much stiffer than glass fibre and more costly, it reinforces polymer, metal, ceramic and carbon matrices.
Engineering material
Aramid fibre
A fibre that is light, strong and tough, valued for its resistance to impact damage, and one of the four fibres most used in fibre-reinforced polymers. It is weak in compression and absorbs moisture.
Engineering material
Plant fibre
Fibre taken from plants — flax, hemp, ramie, jute, kenaf, sisal — whose main structural component is cellulose. Most plant fibres are thermally unstable above about 200 °C.
Engineering material
Silicon carbide fibre
Small-diameter ceramic fibre of silicon carbide, made in stoichiometric and carbon-rich types that differ in high-temperature behaviour. It is the reinforcement of SiC/SiC composites.
Matrices, particles and interphases
Materials that serve as matrices, as particulate reinforcement or as fibre coatings. Several serve in more than one role, which is why the role is recorded on the link and not on the material.
Engineering material
Thermosetting polymer
A polymer that cures by irreversible cross-linking into an insoluble solid — epoxy, unsaturated polyester, vinyl ester, phenolic, polyimide and bismaleimide resins. It cannot be re-melted once cured.
Engineering material
Thermoplastic polymer
A polymer that softens when heated and hardens when cooled, repeatedly, without chemical curing — polypropylene, polyethylene, PEEK and others. Its high melt viscosity makes impregnating fibres harder than with a thermoset.
Engineering material
Aluminium alloys
Alloys of aluminium, such as Al–Si, Al–Cu and Al–Si–Mg. They are the matrices of aluminium-matrix composites and one of the metal families sources name as common matrices of metal-matrix composites for aircraft.
Engineering material
Magnesium alloys
Alloys of magnesium. They are one of the three metal families sources name as common matrices of metal-matrix composites for aircraft.
Engineering material
Titanium alloys
Alloys of titanium. They are one of the three metal families sources name as common matrices of metal-matrix composites for aircraft.
Engineering material
Silicon carbide
A technical ceramic. It is the matrix of SiC/SiC composites and, as particles, a common reinforcement of aluminium-matrix composites — one material in two different roles.
Engineering material
Alumina
Aluminium oxide as a technical ceramic. As particles it is one of the common reinforcements of aluminium-matrix composites.
Engineering material
Pyrolytic carbon
Carbon deposited from a hydrocarbon by thermal decomposition. It forms the matrix that chemical vapour infiltration deposits in carbon–carbon composites and is a common interphase coating on fibres in carbon and ceramic matrices.
Engineering material
Boron nitride
A ceramic used as a thin interphase coating on silicon carbide fibres in SiC/SiC composites, chosen for compliance and oxidation resistance.
Polymer routes: open moulds and continuous processes
Routes in which resin meets fibre on a single mould surface, or continuously on a mandrel or through a die.
Manufacturing process
Hand lay-up
An open-mould process in which resin is worked by hand into fibre fabrics and left to cure at ambient conditions. It is simple and cheap, but quality depends on the laminator.
Manufacturing process
Spray-up
An open-mould process in which chopped fibre and catalysed resin are sprayed together into a mould. It is cheap but limited to short fibres and gives heavy, resin-rich laminates.
Manufacturing process
Filament winding
A process in which resin-wetted continuous fibre tows are wound onto a rotating mandrel. It is the predominant route for hollow axisymmetric parts such as pressure tanks and pipes.
Manufacturing process
Pultrusion
A continuous process in which fibres are pulled through a resin bath and a heated die where the resin cures. It makes profiles of constant cross-section.
Polymer routes: closed moulds and prepregs
Routes that shape the part in a closed tool or under a bag, from liquid moulding and moulding compounds to prepreg cured in or out of an autoclave.
Manufacturing process
Resin transfer moulding
A closed-mould process in which resin is injected into a dry fibre preform clamped between matched mould tools. It can make continuous-fibre structural parts.
Manufacturing process
Vacuum-assisted resin infusion
A variant of resin transfer moulding in which the upper mould is replaced by a vacuum bag and vacuum draws resin through the dry reinforcement. One tool surface makes very large parts affordable.
Manufacturing process
Compression moulding
A closed-mould process in which a charge of fibre and resin, often sheet or bulk moulding compound, is pressed into the shape of the mould. It is fast and repeatable but capital-intensive.
Manufacturing process
Injection moulding of fibre-reinforced compounds
A closed-mould process in which pellets of polymer containing fibres are melted and forced into a metal mould. It is the high-volume route for short-fibre thermoplastic composites.
Manufacturing process
Prepreg lay-up with autoclave cure
A process in which plies of prepreg — fibres held in partially cured resin — are laid up and then cured under heat and pressure in an autoclave. It is the established aerospace route, slow and energy-intensive.
Manufacturing process
Out-of-autoclave prepreg curing
Curing of prepregs formulated to consolidate under vacuum pressure alone and at lower temperatures than an autoclave cure. It avoids the autoclave’s cost and energy use.
Metal-matrix routes
Routes named for the state of the metal: molten in stir casting and infiltration, powdered in powder metallurgy.
Manufacturing process
Stir casting
A liquid-state route in which reinforcement particles or short fibres are stirred into molten metal and the mixture is cast. It is described as the most widely used and least expensive route for metal-matrix composites.
Manufacturing process
Powder metallurgy of metal-matrix composites
A solid-state route in which reinforcement is blended with metal powders, compacted and sintered, often followed by forging or extrusion. It gives close control of microstructure with little reaction between the constituents.
Manufacturing process
Liquid metal infiltration
A liquid-state route in which molten matrix metal is forced or drawn into a porous preform of the reinforcement. The metal becomes the matrix without reacting to form it, which distinguishes it from reactive melt infiltration.
Ceramic-matrix and carbon–carbon routes
Routes that grow a ceramic or carbon matrix inside a fibre preform — from a gas, a polymer precursor or a reacting melt.
Manufacturing process
Chemical vapour infiltration
A process in which precursor gases diffuse into a porous fibre preform and decompose to deposit the matrix inside it. It is gentle on fibres but slow, and leaves residual porosity.
Manufacturing process
Precursor infiltration and pyrolysis
A process in which a liquid preceramic polymer is infiltrated into a fibre preform and pyrolysed into ceramic, repeated many times because the precursor shrinks. It suits complex shapes at moderate temperature.
Manufacturing process
Reactive melt infiltration
A process in which a molten metal such as silicon or zirconium is drawn into a porous preform and reacts with carbon or boron there to form a ceramic matrix. It is fast and dense but exposes the fibres to aggressive melts.
Hub last updated 2026-10-30. Every entry above is a structured record; the bracketed references link to the entities whose claims support each statement.