Carbon fiber (CF) is a new type of fiber material with a carbon content of more than 95% and high-modulus fiber. It is a microcrystalline graphite material made of organic fibers such as flake graphite microcrystalline stacked along the axial direction of the fiber, and obtained by carbonization and graphitization treatment. Carbon fiber is "soft on the outside and rigid on the inside", the weight is lighter than that of aluminum, but the strength is higher than that of steel, and it has the characteristics of corrosion resistance and high modulus, which is an important material in the national defense and military industry and civilian use. It not only has the intrinsic properties of carbon materials, but also has the soft processability of textile fibers, and is a new generation of reinforced fibers.

Carbon fiber has many excellent properties, carbon fiber axial strength and modulus are high, low density, high specific performance, no creep, ultra-high temperature resistance in non-oxidizing environment, good fatigue resistance, specific heat and conductivity between non-metal and metal, small thermal expansion coefficient and anisotropy, good corrosion resistance, good X-ray transmittance. Good electrical and thermal conductivity, good electromagnetic shielding, etc.

Compared with the traditional glass fiber, the Young's modulus of carbon fiber is more than 3 times, and compared with Kevlar fiber, the Young's modulus is about 2 times that of it, and it is insoluble and non-swelling in organic solvents, acids and alkalis, and has outstanding corrosion resistance.

Fields of application

Carbon fiber is an important strategic material for the development of national defense and military industry and national economy, and is a technology-intensive key material. In the context of the rapid industrialization of the world today, the use of carbon fiber is becoming more diversified. China has used long fiber as a kind of high-performance fiber, and carbon fiber composite materials have irreplaceable advantages in occasions that require high temperature and high physical stability. 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.

Carbon fiber carbon materials have been widely used in various fields of military and civilian industries. From aerospace, aviation, automobile, electronics, machinery, chemical, textile and other civil industries to sports equipment and leisure products. Carbon fiber reinforced composite materials can be used in military fields such as aircraft manufacturing, industrial fields such as wind power blades, electromagnetic shielding and electrical removal 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. bats and other sports fields. Carbon fiber is a typical new industrial material in the high-tech field.

Composites

Carbon fiber is traditionally used in addition to being used as an insulating material. It is mostly added to resins, metals, ceramics, concrete and other materials as reinforcing materials to form composite materials. Carbon fiber has become the most important reinforcement material for advanced composites. Because carbon fiber composite materials have the characteristics of light and strong, light and rigid, high temperature resistance, corrosion resistance, fatigue resistance, good structural dimensional stability, good design, and large-area integral molding, they have been widely used in various fields of aerospace, national defense and civil industry. Carbon fiber can be processed into fabrics, felts, mats, belts, paper and other materials. High-performance carbon fiber is the most important reinforcement material for the manufacture of advanced composites.

Civil construction

In the field of civil engineering and construction: carbon fiber is also used in industrial and civil buildings, railway and highway bridges, tunnels, chimneys, tower structures, etc. It has the characteristics of low density, high strength, good durability, strong corrosion resistance, resistance to acid, alkali and other chemicals, good flexibility and strong strain. The truss frame roof made of carbon fiber tubes is about 50% lighter than steel, which makes large structures practical, and the construction efficiency and seismic performance are greatly improved. In addition, when carbon fiber is used as a reinforced concrete structure, there is no need to add bolts and rivets to fix, which has less disturbance to the original concrete structure and the construction process is simple.

Aerospace

Carbon fiber is an indispensable strategic basic material for cutting-edge weapons and equipment such as rockets, satellites, missiles, fighter jets and ships. The application of carbon fiber composite materials to the missile body and engine shell of strategic missiles can greatly reduce weight and improve the range and assault capability of missiles, such as the three-stage shells of intercontinental missiles developed by the United States in the 80s are all made of carbon fiber and epoxy resin composite materials. Carbon fiber composite materials have also begun to be widely used in the new generation of fighters, such as the United States fourth-generation fighter F22 uses about 24% carbon fiber composite materials, so that the fighter has the characteristics of hypersonic cruise, over-the-horizon combat, high maneuverability and stealth. Boeing has launched a new generation of high-speed wide-body passenger aircraft sonic cruisers, about 60% of the structural components will be made of reinforced carbon fiber plastic composites, including the wings. The performance of carbon fiber composite brake prefabricated parts developed by China has reached the international level. The domestic carbon and carbon brake discs prepared by this prefabricated technology have been equipped in batches for military aircraft of key models of national defense, and are used in B757 civil aircraft, and the use of other models is also in the experimental assessment, and will be used in tanks, high-speed trains, luxury cars, racing cars, etc. Carbon fiber is lighter than aluminum but has similar strength. Carbon fiber also has an important application value on ships, which can reduce the structural weight of ships and increase the payload of ships, thereby improving the ability to transport war materials. Since the use of carbon fiber materials can significantly reduce the weight of the structure, fuel efficiency can be significantly improved. Aircraft, satellites, rockets, and other spacecraft made of composite materials made of carbon fiber and plastic are less noisy, and they can save a lot of fuel due to their low mass and low power consumption. It has been reported that for every 1 kg reduction in the mass of the space vehicle, the launch vehicle can be reduced by 500 kg.

Carbon fiber is also the perfect material to make modern transportation such as large civil aircraft, automobiles, and high-speed trains "lightweight". The demand for carbon fiber in aerospace applications is increasing, and the new generation of large commercial airliners, the Airbus A380 and Boeing 787, use around 50% carbon fiber composites. The Boeing 777 aircraft uses carbon fiber as structural materials, including horizontal and vertical transverse tails and beams, which are called important structural materials, so their quality requirements are extremely demanding. The Boeing 787's fuselage is also made of carbon fiber, which allows the aircraft to fly faster and consume less fuel, while increasing cabin humidity for more passenger comfort. Airbus is also using a lot of carbon fiber in their aircraft, which will be used in large numbers on the new A380 airliner. This results in a 20% reduction in the structural weight of the aircraft fuselage, resulting in fuel savings of 20% compared to comparable aircraft, resulting in significantly lower operating costs and reduced CO2 emissions.

Automotive Materials

Carbon fiber materials have also become the preferred material for automobile manufacturers.

It began to be widely used in the interior and exterior decoration of automobiles. As an automotive material, the biggest advantage of carbon fiber is that it is light in weight and strong in strength, the weight is only 20% to 30% of steel, but the hardness is more than 10 times that of steel. Therefore, the use of carbon fiber materials in automobile manufacturing can make the lightweight of automobiles, make breakthroughs, and bring social benefits of energy saving. The industry believes that the use of carbon fiber in the field of automobile manufacturing will increase.

A carbon fiber car developed by the Chinese Academy of Sciences is mainly on the shell: on the hood of the car made of ordinary materials, the hammer is struck hard, and there is likely to be a depression on the paint cover, but the body of this car is very strong, and it will rebound rapidly after hitting the cover hard, and the surface is not damaged at all. According to the researchers, cars made of carbon fiber composite materials are lighter and faster than ordinary cars made of steel. Carbon fiber cars abandon the traditional steel structure and are made of a large number of carbon fiber materials, which can reduce the weight of ordinary steel cars by 60%. With the same use of fuel, the car can drive an additional 50 kilometers per hour.

Although carbon fiber is light, it has good safety, although carbon fiber looks like plastic, but in fact, this material has stronger impact resistance than steel, especially the steering wheel made of carbon fiber, which has higher mechanical strength and impact resistance. With the combination of composite materials, carbon fiber cars have become armored vehicles in family cars. This carbon fiber material has been applied to the skirts of high-speed trains.

Fiber reinforcement

Carbon fiber reinforcement includes carbon fiber cloth reinforcement and carbon fiber plate reinforcement. The research on the use of carbon fiber materials for the reinforcement and repair of concrete structures began in the 80s in developed countries such as the United States and Japan. China's technology started very late, but with the rapid development of China's economic construction and transportation, a considerable part of the existing buildings due to the low design load standards at that time caused historical problems, some buildings due to the change of use functions, it is difficult to meet the needs of the current standard use, and it is urgent to repair and reinforce. There are many commonly used reinforcement methods, such as: enlarged cross-section method, outer steel reinforcement method, bonded steel reinforcement method, carbon fiber reinforcement method, etc. Carbon fiber reinforcement repair structure technology is another new type of structural reinforcement technology after increasing the concrete section and sticking steel.

Since 1997, China has introduced carbon fiber composite materials from abroad to reinforce concrete structure technology. It has become a hot spot for research and engineering applications. Dozens of universities and research institutes in China have carried out this research work, and have achieved a number of research results close to the international advanced level. As China has the largest civil construction market in the world, the application of carbon fiber reinforced building structures will show a growing trend.

Sporting goods

Carbon fiber is used in the field of sports and leisure, such as cues, fishing rods, tennis rackets, badminton rackets, bicycles, ski poles, skis, windsurfing masts, marine hulls and other sports goods are one of the main users of carbon fiber. Carbon fiber is used in daily necessities, such as audio, bath bombs, heaters and other household appliances, as well as mobile phones, laptops and other electronic products.

The three most important applications in sports applications are bat and racket frames. It is estimated that 34 million bats are produced annually. 40% of the world's carbon fiber bats are made of carbon fiber. The world's production of carbon fiber fishing rods is about 20 million pairs per year. The market capacity of tennis racket frames is about 6 million per year, and other sports applications include ice hockey sticks, ski poles, etc. Carbon fiber is also used in other marine sports such as rowing and rowing.