Understanding Carbon Fiber

        Carbon Fiber (abbreviated as CF) is a high-performance inorganic fiber produced by pyrolysis and carbonization of organic fibers under high-temperature conditions, with a carbon content exceeding 90%. Carbon fiber boasts excellent properties such as high strength, high modulus, low density, corrosion resistance, high-temperature resistance, and friction resistance. It is a star product in today's materials science and is widely used in aerospace, rail transportation, shipbuilding, new energy, and other fields.

I. Types and Preparation of Carbon Fiber
        Carbon fiber is mainly classified into three categories based on its raw materials: polyacrylonitrile (PAN)-based carbon fiber, pitch-based carbon fiber, and viscose-based carbon fiber. Among them, PAN-based carbon fiber has relatively low process difficulty, excellent finished product quality, and superior mechanical properties. It is currently the most widely used and produced type of carbon fiber, occupying more than 90% of the market share.

        The preparation process of carbon fiber includes steps such as stabilizing the organic fiber (at 200～400°C), carbonizing it (at 400～1400°C), and graphitizing it (above 1800°C). Additionally, vapor-phase growth is another method for preparing carbon fiber. By reacting a mixture of methane and hydrogen in the presence of a catalyst at a high temperature of 1000°C, discontinuous chopped carbon fiber can be obtained.

II. Properties of Carbon Fiber
        Carbon fiber has the highest specific strength and specific modulus among the high-performance fibers currently in mass production. Its density is less than one-fourth of steel, but its strength is 7 to 9 times that of steel. Carbon fiber also exhibits excellent corrosion resistance, high-temperature resistance, friction resistance, and fatigue resistance. Additionally, it has good vibration damping properties, electrical and thermal conductivity. Its low moisture expansion coefficient and high X-ray penetrability make it irreplaceable in certain special fields.

III. Applications of Carbon Fiber
        Carbon fiber has a wide range of applications and can be divided into aerospace-grade and industrial-grade categories based on its use, often referred to as small tows and large tows. Aerospace-grade carbon fiber is mainly used in the defense industry and sporting goods, such as airplanes, missiles, rockets, satellites, fishing rods, golf clubs, tennis rackets, etc. Industrial-grade carbon fiber is applied in textiles, medicine and health, electromechanical engineering, civil engineering, transportation, energy, and other civilian industries.

        Specifically, carbon fiber is used in the aerospace industry to manufacture aircraft structural components, satellite parts, and rocket casings to reduce weight and improve flight efficiency. In the new energy vehicle sector, carbon fiber is used to make battery enclosures, body structural components, and drive shafts to enhance vehicle energy efficiency and safety. In the wind power industry, carbon fiber is used to manufacture wind turbine blades, making them lighter, stronger, and more durable.

IV. Development of the Carbon Fiber Industry
        Japan leads in the development of the carbon fiber industry. As early as the 1960s, Japanese scientists invented PAN-based and pitch-based carbon fibers and continuously improved their properties and applications through industrialization and technological innovation. Currently, companies such as Toray, Teijin, and Mitsubishi Chemical in Japan are leading players in the global carbon fiber industry.

        Although China's carbon fiber industry started late, it has developed rapidly in recent years, with rapidly growing market demand. However, China's carbon fiber industry still faces significant gaps in production capacity and technology compared to international advanced levels, with bottlenecks and deficiencies in upstream and downstream parts of the industry chain. To promote the development of the carbon fiber industry, the Chinese government has increased support for it, encouraging enterprises to strengthen independent research and development and brand building to improve product quality and technology.

V. Conclusion
        As a high-performance material, carbon fiber plays a crucial role in aerospace, new energy vehicles, wind power, and other fields. With technological advancements and industrial development, the application fields of carbon fiber will further expand, and market demand will continue to grow. China's carbon fiber industry should strengthen international cooperation, introduce excellent technology and talent, and improve product quality and technology to achieve industrial upgrading and sustainable development. In the future, carbon fiber will demonstrate its unique advantages and value in more fields.