Composite materials. Carbon fiber composite is an inorganic high-performance fiber with carbon content higher than 90%, which is transformed from organic fiber through a series of heat treatments. It is a new material with excellent mechanical properties, which not only has the inherent characteristics of carbon materials, but also has the softness and machinability of textile fibers, and is a new generation of reinforced fibers. Carbon fiber is a kind of special fiber with carbon as the main element, and its carbon content varies with different types, generally above 90%. Carbon fiber has the characteristics of ordinary carbon materials, such as high temperature resistance, friction resistance, electrical conductivity, thermal conductivity and corrosion resistance. However, unlike ordinary carbon materials, its shape is obviously anisotropic and soft, and it can be processed into various fabrics, showing high strength along the fiber axis. Carbon fiber has low specific gravity, so its specific strength is high. The main purpose of carbon fiber is to make structural materials by compounding with resin, metal, ceramics and other substrates. The comprehensive indexes such as specific strength and specific modulus of carbon fiber reinforced epoxy resin composites are the highest among the existing structural materials. Carbon fiber composites have advantages in areas with strict requirements such as density, stiffness, weight and fatigue characteristics, as well as occasions requiring high temperature and high chemical stability.