Advanced Materials for Composites 135

ablation

The erosion or vaporization of material from causes like abrasion and heat. Parts made from carbon-carbon composites are resistant to ablation.

advanced composite

A composite made from specially formulated resins and high performance fibers. Advanced composites are used for applications that require a customized mixture of resins and reinforcements to produce specific properties in the composite.

alloy

A metal consisting of a mix of two or more elements, one of which must be a metal. Alloys can be used to make metal matrix composites.

aluminum

A ductile metal used in metal matrix composites.

ambient temperature

The nominal temperature of the air that surrounds devices and systems. Suppliers of composite materials usually recommend a maximum ambient temperature in which the part can function.

aramid

An advanced composite material made from nylon. Aramid fiber reinforcements are strong and flexible.

aromatic chemical

A highly stable type of chemical used in thermoplastic resins. Aromatic chemicals often have a strong odor.

autoclave

A pressure vessel that promotes faster curing through a combination of vacuum and heat. Advanced composites often require autoclave curing.

borides

Boron-based compounds used to create ceramic matrices for advanced composites.

boron

A semi-metallic chemical element used in advanced composite reinforcements. Boron fibers are much stronger than carbon fibers or glass fibers.

brittleness

The measure of a material's tendency to fracture from being drawn, stretched, or formed. As the rigidity of a material increases, brittleness increases.

carbides

Carbon-based compounds used to create ceramic matrices for advanced composites.

carbon

A non-metallic chemical element used in advanced composite reinforcements and matrices. Carbon is very strong and has high resistance to heat.

carbon fiber

A high-strength, high-modulus reinforcement used in advanced composites. Carbon fibers may be mixed with a carbon matrix to form carbon-carbon composites.

carbon-carbon composite

A composite made from carbon fibers and a carbon matrix. Carbon-carbon composites have the best heat resistance of any composite material.

ceramic

A hard, brittle material that can withstand high temperatures and resist corrosion. Some advanced composite matrices are made from ceramic materials.

ceramic matrix composite

A highly specialized advanced composite often used for aerospace applications. CMCs are stiff, lightweight, and can withstand extremely high temperatures.

C-glass

A type of glass fiber that provides greater resistance to chemicals. A small portion of advanced composites use C-glass.

char

A type of material that is formed from burning plastic in a low-oxygen environment. Carbon matrices are created from the carbon-containing char of polymer-based resins such as phenolics.

continuous

Covering the entire dimension of a part without a break or interruption. Continuous fibers provide greater strength but are more expensive to integrate with the matrix.

copper

A ductile, thermally and electrically conductive metal used in metal matrix composites.

cure time

The amount of time it takes for the molecules in a composite to cross-link. Longer cure times increase the cost of making the composite and the possibility of something going wrong in the curing process.

degassing

Removing dissolved gases from a liquid. Volatile gases and trapped air must be removed from metal matrix composites through degassing.

discontinuous

Characterized by being chopped or cut into small pieces. In ceramic matrix composites, whiskers tend to have the best mechanical properties of the discontinuous reinforcements.

ductility

The ability of metal to be drawn, stretched, and deformed without breaking.

elasticity

The measure of a material's ability to return to its original shape after being deformed from stress.

environmental properties

The characteristics of a material that determine how it reacts to other phenomena in close proximity. Environmental factors that affect a material include noise, air quality, machine vibration, moisture, and temperature, among other factors.

epoxy resin

A tough, heat-resistant resin used in advanced composites. Boron fibers are typically applied to a tape that has been preimpregnated with epoxy resin.

ether

An organic compound found in polyetheretherketone.

fiber

A slender, thread-like reinforcing material used in composites. Fibers are larger than whiskers.

fiberglass

Reinforcement material made from extremely fine strands of glass. Fiberglass is the most commonly used reinforcement material in composites.

fiberglass reinforced plastics

A commercial composite made from fiberglass and polyester resin.

flammability

The characteristics of a material the determine its ability or tendency to ignite or burn when exposed to an open flame. Some advanced composite applications require materials with low flammability.

glass transition temperature

The point at which a rigid solid becomes pliable and can be formed, shaped, or molded. In general, a higher Tg allows for greater thermal stability and helps to prevent defects during the curing of a part.

ketone

An organic compound found in polyetheretherketone.

magnesium

A strong, lightweight metal used in metal matrix composites.

matrix

The material that binds together the reinforcing fibers of a composite. Advanced composites use specially formulated polymers, ceramics, and carbons as the matrix.

mechanical properties

The characteristics of a material that determine how it reacts when it is subjected to a force that attempts to stretch, dent, scratch, or break it.

metal

A naturally occurring material with high electric and thermal conductivity, luster, density, and strength. Some advanced composite matrices are made from metals and metal alloys.

metal matrix composite

A composite made from a metallic matrix and high-performance reinforcements. MMCs have high levels of strength, stiffness, and relatively high resistance to heat.

metalloid

An element that has the qualities of both a metal and a non-metal. Boron is a metalloid that shares some of the qualities of aluminum, silicon, and carbon.

modulus

The stiffness of a material. Carbon fiber reinforcements have a high modulus.

nickel

A corrosion-resistant metal used in metal matrix composites.

nitrides

Nitrogen-based compounds used to create ceramic matrices for advanced composites.

nylon

A thermoplastic polymer used to make aramid fibers for advanced composites. Nylon is strong and very flexible.

organic compound

A highly stable type of chemical that always contains carbon. Many polymers used in composites are organic compounds.

organic resin

A resin made from carbon-based materials. Phenolic resin is an example of an organic resin.

oxidation

A chemical reaction involving the addition of oxygen and the loss of electrons. Oxidation causes metal to rust.

oxides

Oxygen-based compounds used to create ceramic matrices for advanced composites.

particle

A very tiny piece of material used as a reinforcement in advanced composites.

phenolics

A group of thermoset polymers derived from phenol. Phenolics are often used to create carbon resins.

plasma environment

An environment of partially ionized gas. A plasma environment is extremely disruptive to electrical equipment.

polyester resin

The most widely used thermoset polymer in the composite industry. Fiberglass reinforced plastics are made with unsaturated polyester and fiberglass reinforcement.

polyetheretherketone

PEEK. An advanced thermoplastic polymer used extensively in the aerospace, automotive, and marine industries.

polymer

A long chain of very large molecules made up of many atoms. Polymers are used to make thermoplastic resins for composites.

polymer matrix composite

A composite made from a polymer resin. Polymer matrix composites are not as strong or heat-resistant as metal matrix and ceramic matrix composites.

polyphenylene sulfide

PPS. An advanced thermoplastic resin that can withstand relatively high temperatures. PPS is flame retardant and has good resistance to chemicals, mildew, sunlight, and abrasion.

preform

A tough but flexible fiberglass structure that is roughly the same shape as the final product. The powdered matrix of a CMC is made into a preform which is heated and then formed into a composite part.

prepreg

A ready-to-mold sheet of fiber reinforcement that has been preimpregnated with resin. A prepreg made with boron fibers is very stiff.

radiation

Energy emitted in the form of particles or waves. Prolonged exposure to radiation can damage composites.

reinforcement

The part of the composite that provides strength, stiffness, and the ability to carry a load. The reinforcement material used in advanced composites is often a high-performance fiber.

S-glass

A type of glass fiber that provides greater strength and can withstand higher temperatures than E-glass. Advanced composites are more likely to use S-glass.

silicon carbide

A chemical compound made of up carbon and silicon. Silicon carbide is used to make high-performance reinforcements and matrices for composites.

solvent

A substance that dissolves another substance.

space debris

Natural and man-made objects found beyond the earth's atmosphere. Space debris can strike and damage a space vehicle.

strength

The measure of a material's ability to carry a load. When selecting materials for advanced composites, manufacturers must know the strength of the material.

tensile stress

The internal load that a part is subjected to when pulled apart by an applied force. Carbon fiber reinforcements can withstand a high amount of tensile stress.

thermal properties

The characteristics of a material that determine how it reacts when it is subjected to excessive heat, or heat fluctuations over time.

thermoplastic

A polymer composed of molecules that are not cross-linked, or are cross-linked to a weaker degree. Thermoplastics can be melted and hardened repeatedly without changing their chemical structure.

thermoset

A polymer that cannot be re-melted or reformed once it has cured. Thermosets have higher rigidity and better thermal stability than thermoplastics, but they take longer to process.

titanium

Ti. A silvery white "space age" metal with a high strength-to-weight ratio, excellent flexibility, and exceptional corrosion resistance. Titanium can be a component of metal matrix composites and is commonly used in medical components and in aerospace applications.

toughness

The measure of the composite's ability to absorb mechanical forces before it breaks. Tough materials generally have some measure of elasticity.

traditional composite

A composite that uses a relatively consistent combination of polymer resin and fiberglass reinforcement. Traditional composites are low-cost and are processed by traditional methods.

vacuum environment

An environment with very low density and pressure, such as outer space. In a vacuum, heat cannot be transferred through convection.

warpage

The deformation of a part after molding. Parts made with polyphenylene sulfide resins are vulnerable to warpage.

wet-out

The condition of being completely covered, and filled, with resin. Thermoplastic resins allow for good fiber wet-out in composites.

whisker

A very thin, short filament. Whiskers are smaller than chopped fibers.