Carbon fiber combines the strong tensile strength of carbon material and the softness and processability of fiber. It is a 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. The density is about 1.5 to 2.0 grams per cubic centimeter, which is mainly determined by the temperature of the carbonization treatment, in addition to the structure of the raw silk. Generally, it is graphitized at a high temperature of 3000 ° C, and the density can reach 2.0 g per cubic centimeter. In addition, its weight is very light, its specific gravity is lighter than aluminum, less than 1/4 of steel, and its strength is 20 times that of iron.
Carbon fiber has a different coefficient of thermal expansion than other fibers, and it has an anisotropic character. The specific heat capacity of carbon fiber is generally 7.12. The decrease in thermal conductivity with increasing temperature is a negative value (0.72 to 0.90) parallel to the fiber direction and a positive value (32 to 22) perpendicular to the fiber direction.
The specific resistance of carbon fiber is related to the type of fiber. At 25 ° C, the high modulus is 775 and the high strength carbon fiber is 1500 per cm. This allows the carbon fiber to have the highest specific strength and specific modulus among all high performance fibers.
Compared with metal materials such as titanium, steel and aluminum, carbon fiber has the characteristics of high strength, high modulus, low density and small coefficient of linear expansion, which can be called the king of new materials.
In addition to the characteristics of ordinary carbon materials, carbon fiber has a remarkable anisotropic and soft shape, can be processed into various fabrics, and exhibits high strength along the fiber axis direction due to its small specific gravity. Carbon fiber reinforced epoxy resin composite The material, its specific strength and specific modulus, is the highest among the existing structural materials.