Carbon fiber is a new material with excellent mechanical properties, its specific gravity is less than 1/4 of the steel, carbon fiber resin composite material tensile strength are generally more than 3,500Mpa, is 7-9 times the steel, tensile modulus of elasticity of 23,000 ~ 43,000Mpa is also higher than steel. Therefore, the specific strength of CFRP, that is, the ratio of the strength of the material to its density can reach 2000Mpa / (g/cm3) or more, while the specific strength of A3 steel is only 59Mpa / (g/cm3) or so, its specific modulus is also higher than steel. The higher the specific strength of the material, the smaller the weight of the component, the higher the specific modulus, the greater the stiffness of the component, in this sense, has predicted the broad prospects for the application of carbon fiber in the project, a variety of emerging composite materials (such as polymer composites, metal-based composites, ceramic-based composites) of the excellent performance of many people predicted that mankind in the application of materials from the age of steel into a composite material The era of wide application.
Carbon fiber is an inorganic polymer fiber containing more than 90% carbon. Which contains more than 99% of the carbon called graphite fiber. Carbon fiber axial strength and modulus is high, no creep, good fatigue resistance, specific heat and electrical conductivity between non-metal and metal, small coefficient of thermal expansion, good corrosion resistance, low density of the fiber, X-ray permeability is good. However, its impact resistance is poor, easy to damage, oxidation occurs under the action of strong acids, and metal composite will occur when the metal carbonization, carburization and electrochemical corrosion phenomena. Therefore, carbon fiber must be surface treated before use.
Carbon fiber can be used respectively with polyacrylonitrile fibers, asphalt fibers, viscose filaments or phenolic fibers produced by carbonization; according to the state is divided into filament, staple fibers and short-cut fibers; according to the mechanical properties are divided into general-purpose and high-performance type. General-purpose carbon fiber strength of 1000 megapascals (MPa), modulus of about 100GPa. High-performance carbon fiber is divided into high-strength type (strength 2000MPa, modulus 250GPa) and high model (modulus 300GPa or more). Strength greater than 4000MPa is also known as ultra-high-strength type; modulus greater than 450GPa is called ultra-high model. With the development of the aerospace and aviation industry, there is also a high-strength, high-extensile carbon fiber, whose elongation is greater than 2%. The largest amount of polyacrylonitrile PAN-based carbon fiber.
Carbon fiber can be processed into fabrics, mats, mats, tape, paper and other materials. In addition to carbon fiber used as insulation materials, generally not used alone, more as a reinforcing material added to the resin, metal, ceramics, concrete and other materials, constituting a composite material. Carbon fiber reinforced composite materials can be used as aircraft structural materials, electromagnetic shielding in addition to electrical materials, artificial ligaments, such as body substitute materials and used in the manufacture of rocket shells, motorized boats, industrial robots, automotive leaf springs and drive shafts.
Carbon fiber is a dual-use new material, belonging to the technology-intensive and politically sensitive key materials. Previously, the United States-led Paris Coordinating Committee (COCOM), the then socialist countries to implement the embargo blockade policy, in March 1994, COCOM has been dissolved, but the shadow of the embargo blockade is still hanging over the sky, the advanced carbon fiber technology is still not attracted to come in, especially high-performance PAN-based filament technology, even if China's entry into the WTO, the situation will not be a major change. Therefore, in addition to the country continue to self-reliance in the development of carbon fiber industry, there is no other choice. Therefore, foreign countries, especially Japan and South Korea, which are leading in carbon fiber production technology, have been maintaining a rather cautious attitude towards the export of carbon fiber materials and products from China, and only a small number of Chinese enterprises have been able to establish a cooperative relationship with them and have import channels for their products.
Currently, the world's carbon fiber production reached 40,000 tons / year or more, the world is mainly Japan Toray, Toho Rayon and Mitsubishi Rayon three companies as well as the U.S. HEXCEL, ZOLTEK, ALDILA three companies, as well as Germany's SGL SGL Group, South Korea's Tae Kwang Industry, Taiwan Province of China's Formosa Plastics Group, a small number of units have mastered the production of carbon fibers Core technology, and there are large-scale production. At present, there is no annual output of 100t in the motherland of large-scale carbon fiber plant, most of them are still in the pilot amplification stage. It is worth mentioning that China's Taiwan Province of Formosa Plastics Group, in the mid-80's years from the United States Hitco introduced a hundred tons of carbon fiber production line, digested, absorbed and supporting the rapid development of Formosa Plastics production increased very quickly, but the improvement in the quality of carbon fibers is not large.
China's carbon fiber research began in the 1960s, the 1980s began to study high-strength carbon fiber. Progress has been slow over the years, but some achievements have been made. Entering the 21st century since the development of faster, Anhui Huawan carbon fiber company took the lead in the introduction of 500 tons / year of raw silk, 200 tons / year PAN-based carbon fiber (only Toray carbon fiber T300 level), so that China's carbon fiber industry has entered the industrialization. Subsequently, a number of manufacturers have joined the ranks of carbon fiber production. According to incomplete statistics, at present, China has 12 production scale of different sizes (5 to 800 tons / year) of PAN-based carbon fiber manufacturers, with a combined production capacity of 1,310 tons / year, the product specifications for the 1K, 3K, 6K, 12K. However, due to the fact that some enterprises do not have the original filament can be burned, the actual total domestic production of carbon fibers is less than 40 tons / year, and the product quality is not very stable, most of them up to the T300 level. Most of them are not up to T300 level. Happily, from 2000 onwards, China's carbon fiber to technical diversification, giving up the original nitric acid method of raw silk manufacturing technology, the use of dimethyl sulfoxide as a solvent for one-step wet spinning technology has been successful. At present, the use of independent technology to develop a small number of domestic T300, T700 carbon fiber products have reached the international level of similar products.
With the growing demand for carbon fiber in China in recent years, carbon fiber has been listed as the national chemical fiber industry focus on supporting new products, and has become a hot spot for research and development of domestic new materials industry. According to incomplete statistics, the proposed and under construction of carbon fiber production enterprises have 11, with a total production capacity of 7100 tons of raw silk / year, 1560 tons of carbon fiber / year, of which there are four enterprises under construction, with a total production capacity of 1100 tons of raw silk / year, carbon fiber 470 tons / year.
Despite the slow development of China's carbon fiber production, while consumption has been gradually increasing, the market demand is strong. The main uses include sports equipment, general industry and aerospace, etc., of which the use of sports and leisure goods is the largest, accounting for about 80% to 90% of consumption. China's demand for carbon fiber has exceeded 3,000 tons / year, in 2010 will exceed 5,000 tons / year. The main application areas are: mature market aerospace and defense field (aircraft, rockets, missiles, satellites, radar, etc.) and sports and leisure goods (golf clubs, fishing gear, tennis rackets, badminton rackets, archery shafts, bicycles, rowing boats, etc.); emerging markets are reinforced plastics, pressure vessels, building reinforcement, wind power, friction materials, drilling platforms, etc.; to be developed in the market are automotive, medical equipment, new energy etc.
China's carbon fiber composite material development began in the mid-1970s, after nearly 40 years of development, has made great progress, in the aerospace leading products (bullet, arrow, star, ship) has been widely used. In recent years, China's sports and leisure goods and pressure vessels and other areas of carbon fiber demand is growing rapidly, the rapid development of aerospace technology in urgent need of high-performance carbon fibers and their composite materials, etc., the market demand is even more robust.
In order to meet the growing demand for carbon fiber in the domestic market, the localization and scale of China's carbon fiber industry should be realized as soon as possible. To this end, we must accelerate technological innovation, master the core technology; accelerate the development of raw silk technology, development of high-purity raw silk; strengthen the application of research and market development, and further expand the application areas. Carbon fiber in China has great prospects for development, but should sum up the development of polyester and other chemical fiber lessons learned to avoid blind development, to achieve healthy development.
In order to manufacture large aircraft and the development of aerospace industry, our country must also as soon as possible to achieve high strength in the model of carbon fiber industrialization. However, because high-performance carbon fiber is the development of aerospace and other cutting-edge technology essential materials, long-term by the United States-led Paris Coordinating Committee blockade. Although the PCC was dissolved in March 1994, the shadow of the embargo still exists. Even if the embargo is lifted on our country, the beginning can only be general-purpose carbon fiber, and will not sell us high-performance carbon fiber technology and equipment. Therefore, the development of high-performance carbon fiber must rely on ourselves. China's chemical fiber industry, "11.6.1 Five-Year Plan" development plan put forward "to increase the number of mainly to vigorously develop high-tech fibers," especially high-tech fiber materials related to national industrial security as a top priority, and carbon fiber is the first. Carbon fiber is listed as the first, the country urgently needs a short-term breakthrough in high-tech fiber varieties, to create conditions for the development of China's carbon fiber, we need to seize this opportunity, self-reliance, and strive to innovate, the development of carbon fiber with its own intellectual property rights in order to meet the growing market demand. The national "863 plan" and the relevant ministries and commissions are concerned about the development of China's carbon fiber industry and its pace of industrialization, and to give strong support, many materials experts have done a lot of solid work. During the "11th Five-Year Plan" period, China has launched the related "973 Program". I believe that the "Eleventh Five-Year" will be the golden age of China's carbon fiber industry industrialization.