Composite materials are generally referred to as or more than 2 or more than 2 kinds of materials, such as fibers and other materials, which are made of fiber and other materials. It with fiber reinforced plastic (FRP), fiber reinforced metal (FRM), metal - plastic laminated materials, with light weight, high strength, good stiffness characteristics of, these composite materials in the automobile parts application is very popular.

The composite material is a heterogeneous material, which has the following prominent characteristics compared with other materials:

1) than the strength and the ratio of high modulus. Ratio strength and modulus is the ratio of strength and modulus to density, higher than the strength, the smaller the weight of parts, the higher the modulus, the greater the rigidity of the parts. Therefore, it is of great significance to the high-speed operation of the structure or the need to reduce the weight of the transport tool.

2) the interface between the fiber and the matrix in the fiber reinforced composites can effectively prevent the fatigue crack growth. The fatigue strength limit of most metal materials is 50% to 30% of its tensile strength, while the composites can reach 60% ~ 80%.

3) the incorporation of a small amount of short cut carbon fiber in the thermoplastic can greatly improve its wear resistance, and the increase of the number of short cut carbon fiber can be several times as many as the original. Such as polyvinyl chloride to carbon fiber reinforced for its own 3.8 times, PTFE for its own 3 times; polypropylene for its own 2.5 times; polyamide for its own 1.2 times; polyester for its own 2 times. The use of appropriate plastic and steel composite can be used for wear-resistant objects, such as bearing materials, etc.. The three layer composite material of the surface layer, the porous bronze and the steel plate is used as the inner layer of the composite material, and the good material of the sliding bearing can be made.

4) excellent chemical stability. Fiber reinforced phenolic plastics can be used in chlorine ion in the acidic medium for a long time, the glass fiber reinforced plastic, resistant to acid, salts, esters, and some solvent chemical pipes, pumps, valves and vessels and equipment manufacturing. Such as the use of alkali resistant fiber and plastic composite, but also can be used in alkaline medium. Alkali resistant fiber can be used to replace the steel and cement composite.

5) high temperature resistance. Fiber reinforced composite materials, in addition to the glass fiber low softening point (700 to 900 DEG C) and, other fiber melting or softening point) generally in more than 2000 DEG C, composed of the fiber and metal matrix composites, high temperature strength and modulus were raise. For example, carbon fiber or boron fiber reinforced, the strength and modulus of 400 degrees Celsius basically maintained at room temperature. The same carbon fiber reinforced metal nickel, not only the density decreased, but also improve the high temperature performance. Because the glass fiber reinforced plastic has a very low thermal conductivity, it can be used as a heat resistant material.

6) technology and design is good. Adjustment of reinforced material shape, arrangement and content, can meet the component strength and stiffness requirements and materials and components can a molding, parts, fasteners and connectors number is reduced, the material utilization rate is greatly improved.

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