The advantages and disadvantages of carbon fiber performance are compared by other reinforcement materials: (1) Tensile strength:
The tensile strength of carbon fiber is about 10 times that of steel.
(2) Elastic modulus: The tensile modulus of elasticity of carbon fiber composites is higher than that of steel, but the tensile modulus of aramid and glass fiber composites is only half and one-quarter of steel.
(3) Fatigue strength: The fatigue strength of carbon fiber and aramid fiber composites is higher than that of high-strength filament. Under the action of alternating stress, the fatigue of metal materials is only 30%~40% of the static load strength. Due to the fact that the fiber and matrix composite can alleviate the crack propagation and the possibility of redistribution of the internal force of the fiber, the fatigue of the composite material is high, about 70%~80% of the static load strength, and there are significant signs of deformation before failure.
(4) Weight: about one-fifth of steel.
(5) Comparison with carbon fiber plate: carbon fiber sheet can be pasted on the surface of various shapes of structure, while plate is more suitable for the surface of regular components. In addition, because the amount of underlying resin used when pasting the sheet is larger and the thickness is larger than that of the sheet, the bonding strength with the concrete interface is not as good as that of the sheet. According to the different raw materials and production methods, carbon fiber is mainly divided into polyacrylonitrile (PAN)-based carbon fiber and asphalt-based carbon fiber. Carbon fiber products include PAN-based carbon fiber (high-strength type) and asphalt-based carbon fiber (high-elasticity type).
Subsequently, some manufacturers have joined the ranks of carbon fiber production. According to incomplete statistics, at present, there are 12 PAN-based carbon fiber manufacturers with different production scales (5 to 800 tons / year) in China, with a total production capacity of 1310 tons / year, and product specifications of IK, 3K, 6K, 12K. However, due to the fact that some enterprises do not have precursor to burn, the total output of domestic carbon fiber is less than 40 tons / year, and the product quality is not stable, most of them cannot reach the T300 level. It is gratifying that since 2000, China's carbon fiber has diversified its technology, abandoned the original nitric acid precursor manufacturing technology, and adopted a one-step wet spinning technology using dimethyl sulfoxide as a solvent to achieve success. At present, a small number of domestic T300 and T700 carbon fiber products developed by independent technology have reached the international level of similar products.
Carbon fiber can be processed into fabrics, felts, mats, belts, paper and other materials. In addition to being used as an insulation material, carbon fiber is generally not used alone, but is mostly added to resin, metal, ceramics, concrete and other materials as a reinforcing material to constitute composite materials. Carbon fiber reinforced composite materials can be used as aircraft structural materials, electromagnetic shielding de-energizing materials, artificial ligaments and other body substitute materials, and used in the manufacture of rocket shells, motor boats, industrial robots, automotive leaf springs and drive shafts.
Carbon fiber is a new dual-use material, which is a key material that is technology-intensive and politically sensitive. In March 1994, although COCOM was dissolved, the shadow of the embargo and blockade was still shrouded in the sky, and advanced carbon fiber technology still did not come in, especially high-performance PAN base silk technology. Therefore, there is no other choice but for the Chinese people to continue to develop the carbon fiber industry on their own.
At present, the world's carbon fiber production reaches more than 4,100 tons / year, the world is mainly Japan's Toray, Toho rayon and Mitsubishi silk three companies and the United States HEXCEL, ZOLTEK, ALDILA three companies, as well as Germany's SGL SGL Group, South Korea's Taiguang Industry, Taiwan's Taiwan Plastics Group, and a few other units have mastered the core technology of carbon fiber production, and have large-scale production. At present, there is no large-scale carbon fiber factory with an annual output of 80t in the continent, and most of them are still in the pilot scale-up stage. It is worth mentioning that Formosa Plastics Group in Taiwan Province of China, introduced a <>-ton carbon fiber production line from Hitco Company in the United States in the mid-<>s, and developed rapidly after digestion, absorption and supporting, and Formosa Plastics production increased rapidly, but the improvement of carbon fiber quality was not large.
China's research on carbon fiber began in the 20s of the 60th century, and the 80s began to study high-strength carbon fiber. Progress has been slow over the years, but some progress has been made. Since entering the 21st century, Anhui Huawan Carbon Fiber Company has taken the lead in introducing 500 tons/year precursor and 200 tons/year PAN-based carbon fiber (only Toray carbon fiber T300 level), so that China's carbon fiber industry has entered industrialization.
