Composite materials are heterogeneous or multi phase materials obtained by combination of different materials having different individual properties in order to get a desired material property. The properties of composite are different from the parent materials. The main aim of composite is to obtain a superior property than the parent elements. They have one or more discontinuous phase called reinforcement, which has a light weight structural composition obtained by continuous embedding of carbon fibre in one or more orientations in a polymer matrix. it is among the classification of engineering materials
The function of the fibre is to provide strength and stiffness while the polymer serves as a binder. Carbon fibre reinforced polymer (CFRP) composites are stiffer and stronger when compared fibre reinforced materials. Carbon fibre reinforced polymer is applied in aircraft and air space construction as well as high technology sporting equipment. An example of carbon fibre reinforced polymer is the concrete which is obtained by combining cement, sand and gravel.
In general, composite are classified according to their matrix materials. They include:
- Polymeric matrix composite (PMC)
- Metal matrix composite (MMC)
- Ceramics matrix composite (CMC)
- Carbon- Carbon composite (CCC)
Organic matrix composite: this is comprises of carbon-carbon composite and polymeric matrix composite. They occur naturally and the most common due to it’s low cost of production. Examples are wood and bones. Organic composite by geometry consist of either fibre reinforcement composite or particle reinforced composite.
Organic matrix composites are classified into two; thermoplastic and thermostat.
- Thermoplastic are commercial fibres such as graphite, aromatic fibres and carbon. They lose strength at high temperatures due to the nature of their bond energy and have good mechanical advantages. Examples are; nylon, polystyrene, polythene.
- Thermo-set is mostly applied in automobiles and defense systems. They include; epoxy, phenolic, resin and polyesters. They are environmentally stable.
Metal matrix composite (MMC): these are combination of metal and ceramic materials such as cemented carbide and many more. The properties of MMC include; fracture toughness, high strength, stiffness but has high weight. They are stable at corrosive environments. Metal matrix composite consist of non metallic reinforcement incorporated into metallic phase structure. Examples include; Titanium, copper, aluminum and supper alloys.
Ceramic matrix composite: these are advance materials, their structures consist of metallic and non metallic reinforcement into a ceramic matrix. They are used in high temperature structures such as furnace. They have good corrosive resistance, high melting point and high compressive strength.
Merits of composite
- They have high fatigue life
- They have high stiffness
- Good wear resistance
- Good corrosive resistance
- Improved quality material
Demerits of composite
- The manufacturing process of composite is relatively slow and wastes time
- They are expensive
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