Carbon fiber has two characteristics: strong tensile strength of carbon material and soft processability of fiber, which is a kind of new material with excellent mechanical properties. The carbon fiber has a tensile strength of about 2 to 7 GPa and a tensile modulus of about 200 to 700 GPa. Density of about 1.5 to 2.0 grams per cubic centimeter, which in addition to the original wire structure, mainly depends on the carbonization temperature. Generally after high temperature graphitization of 3000 ℃, the density of up to 2.0 g per cubic centimeter. Coupled with its weight is very light, its weight is even lighter than aluminum, less than 1/4 of steel, iron than the strength of 20 times. Carbon fiber thermal expansion coefficient and other fibers, it has the characteristics of anisotropy. The specific heat capacity of carbon fiber is generally 7.12. The thermal conductivity decreases with increasing temperature and is negative (0.72 to 0.90) parallel to the fiber direction and positive (32 to 22) normal to the fiber direction. The specific resistance of the carbon fiber depends on the type of the fiber, and at 25C, the high modulus is 775, and the high-strength carbon fiber is 1500 per centimeter. This results in the highest specific strength and specific modulus of the carbon fiber in all high performance fibers. Compared with titanium, steel, aluminum and other metal materials, carbon fiber in the physical properties with high strength, high modulus, low density, linear expansion coefficient of small features, can be called the king of new materials.