(1) Carbon Fiber Definition
Carbon fiber is a new type of fiber material with a carbon content of more than 95%, which is high in strength and modulus. It is made of organic fibers such as graphite microcrystals stacked along the fiber axis direction, and then carbonized and graphitized to obtain microcrystalline graphite material. Carbon fiber is lighter in weight than aluminum, but stronger than steel, and has characteristics such as corrosion resistance, high modulus, low density, no creep, good electrical and thermal conductivity, resistance to ultra-high temperatures in non-oxidizing environments, and good fatigue resistance. It not only has the inherent characteristics of carbon materials, but also has the softness and processability of textile fibers, and is widely used in military industry, aerospace, sports equipment, automotive industry, energy equipment, medical devices, engineering machinery, transportation, construction and structural reinforcement and other fields. It is an important strategic material for developing national defense and national economy.
(2) Carbon Fiber Classification
1. According to the raw material system: Carbon fiber is mainly divided into viscose-based, pitch-based and polyacrylonitrile (PAN) based three categories. Among them, PAN-based carbon fiber has the advantages of simple production process, low cost, high carbonization absorption rate, and excellent mechanical properties, making it the most promising precursor for producing high-performance carbon fiber. The comprehensive performance of the carbon fiber prepared by it is the best, the production process is mature and simple, the application is the widest, the output is the highest, and the variety is the most. It is the mainstream of the global carbon fiber market, and its output accounts for more than 90% of the total global carbon fiber output.
2. According to performance: Carbon fiber can be divided into general-purpose, high-strength (GQ), high-strength medium-modulus (QZ), high-modulus (GM), and high-strength high-modulus (QM) carbon fiber. Due to the leading position of Toray Company in Japan in the field of carbon fiber, its product code has become a common indicator in the industry. It is generally divided into high-strength "T" series and high-modulus "M" series. The higher the number, the higher the performance level. The performance level with letters is higher than that without letters (e.g. T300B is greater than T300).
3. According to the size of the tow: Carbon fiber can be divided into small tow and large tow. Small tow carbon fiber was initially dominated by 1K, 3K, and 6K, and gradually developed into 12K and 24K, which are mainly used in high-tech fields such as national defense and military industry, as well as sports and leisure products, such as airplanes, missiles, rockets, satellites, and fishing gear, golf clubs, tennis rackets, etc. Carbon fiber with a tow size of 48K or more is generally referred to as large tow carbon fiber, including 48K, 60K, 80K, etc., which are mainly used in industrial fields such as textiles, medicine and health, machinery and electricity, civil construction, transportation, and energy.
(3) Carbon Fiber Industry Chain
The complete carbon fiber industry chain includes the entire manufacturing process from primary energy to terminal applications. From oil, coal, and natural gas, propylene can be obtained. Currently, under the low oil price situation, the cost of propylene produced from crude oil is the most advantageous; propylene is then oxidized with ammonia to obtain acrylonitrile, which is polymerized and spun to obtain polyacrylonitrile (PAN) precursor fiber, and then undergoes pre-oxidation, low-temperature and high-temperature carbonization through a series of highly difficult and complex processes to obtain carbon fiber, which can be made into carbon fiber fabric and carbon fiber prepreg, serving as raw materials for producing carbon fiber composites; carbon fiber is combined with resins, ceramics, and other materials to form carbon fiber composites, and finally, various forming processes are used to obtain the final products required for downstream applications.
