Mechanical Properties

Carbon fiber composites have high tensile strength, high modulus, low density, high specific strength and very high specific modulus. Compared with traditional metal materials, carbon fiber composites are light in quality, high in strength and high in toughness, and have obvious advantages. Compared with silicon-based fiber composites, which are also new materials, the tensile strength of carbon-based fibers is about 3-7 times higher. The modulus of elasticity of carbon-based fibers is higher than that of silicon-based fibers, so carbon fiber composites have smaller strain under the same external load, and the stiffness of their parts is higher than that of silicon-based fiber composites parts. The elongation at break of high modulus carbon fiber is about 0.5%, that of high-strength carbon fiber is about 1%, that of silicone-based fiber is about 2.6%, and that of epoxy resin is about 1.7%, so the strength of fibers in carbon fiber composites can be fully exploited.

Due to the great brittleness of carbon fiber and poor impact performance, the tensile damage mode of carbon fiber composites belongs to brittle damage, i.e., there is no obvious plastic deformation before pulling off, and the stress-strain curve is a straight line, which is similar to that of glass fibers, except that the modulus is higher than, and the elongation at break is lower than that of glass fibers. Carbon fiber composites have good high and low temperature resistance. In the isolation of air (inert gas protection), 2000 ° C still have strength, liquid nitrogen is not brittle.

Carbon fiber composites have good thermal conductivity. The coefficient of thermal conductivity is high, but there is a tendency to decrease with increasing temperature. Carbon fiber composites along the fiber axial thermal conductivity of 0.04cal/(s*cm*°C); vertical fiber direction of the thermal conductivity of 0.002cal/(s*cm*°C). The linear expansion coefficient of the carbon fiber composite material has a negative temperature effect along the fiber axial direction, i.e., with the increase of temperature, the carbon fiber composite material has a tendency to shrink, good dimensional stability, and good fatigue resistance.

Corrosion resistance

Carbon fiber composites in addition to strong oxidants such as concentrated nitric acid, hypochlorite and dichromate oxidation, general acids and alkalis on its role is very small, than the silicone-based fiber composite materials have better corrosion resistance. Carbon fiber composites do not hydrolyze in wet air like silicon-based fiber composites, and have good water resistance and resistance to moisture and heat aging characteristics. They are also resistant to oil, radiation, and slowing down in the middle of a word movement.

Advantages

In summary, carbon fiber composites have a series of advantages such as light weight, high modulus, high specific strength, low coefficient of thermal expansion, high temperature resistance, thermal shock resistance, corrosion resistance, good shock absorption, etc. These properties are not the characteristics of the traditional metal materials, and also have a strong performance compared to other types of new composite materials. This allows carbon fiber composites to be widely used in many fields, while promoting further research on carbon fiber composites to continue to improve their use.

Application of carbon fiber composites

Carbon fiber composites, with its excellent performance, has been widely used in various fields, mainly, automotive, structural reinforcement engineering, new energy development, leisure goods and so on.

Automobile

At present, the world annual production of passenger cars 50 million, if including trucks and buses for 70 million, with the rapid development of China, India and other countries of the automobile industry, soon the world's annual output of automobiles may indeed exceed 100 million. In addition, the world's annual output of PAN-CF is only tens of thousands of tons, due to the high cost of CFRP, difficult to process, slow molding speed and also subject to the limitations of the regeneration problem, can only be used for sporting goods and industrial industrial fields, to be used in the car, the most important thing is to develop as soon as possible for thermoplastic resins (such as polypropylene, etc.) with a surface-active CF, as well as the CFRTP ultra-high-speed molding technology and secondary processing technology, and secondly, when the CF is used to make the car, the CF is used in the automobile industry. Secondly, when the demand for CF exceeds one million tons, the development of CF made from biomass will be required, although it is still difficult. Thirdly, when such a large scale is reached, it is necessary to develop technologies for regeneration of CFRP and high reuse of CF, and to solve the problems of evaluation and standardization of these materials and related molding processes.