Carbon fiber (CF)
It is an inorganic fiber that is made of organic fibers (viscose-based, pitch-based, polyacrylonitrile-based fibers, etc.) under high temperature environment to form carbon main chain mechanism.
Carbon fiber properties
Carbon fiber materials have excellent mechanical, chemical and electrical properties, including: high strength, 5 times that of steel; small density, 1/5 of steel, 1/2 of aluminum alloy; good heat resistance, can withstand 2000 ℃ The above high temperature; low thermal expansion coefficient, can withstand rapid cooling and heat, low deformation under the condition of large temperature difference; good corrosion resistance, can withstand strong acid corrosion such as sulfuric acid; good tensile strength, can reach 7 ~ 9 times. Carbon fiber material not only has the inherent characteristics of carbon materials, but also has the soft processability of textile fibers. It is an indispensable new generation of new materials for the national economy and national defense construction. It is known as "black gold".
Carbon fiber can be classified according to different dimensions such as the type of raw silk, mechanical properties, and the size of the tow.
Classification of carbon fiber
Classification according to the type of raw yarn: The raw yarn of carbon fiber mainly includes polyacrylonitrile (PAN) raw yarn, pitch fiber and viscose yarn. The carbon fibers produced from these three types of raw yarn are called polyacrylonitrile (PAN) based Carbon fiber, pitch-based carbon fiber, and viscose-based carbon fiber. Among them, polyacrylonitrile (PAN) -based carbon fiber is less difficult to process than the other two types of carbon fiber, and has excellent finished product quality and excellent mechanical properties. It currently occupies the mainstream position, and the output accounts for more than 90% of the total carbon fiber. Gum-based carbon fiber is less than 1%.
Chart: Carbon Fiber Market Shares by Type of Yarn
In the classification by tow size, K represents the number of carbon fiber monofilaments. For example, 1K means that a bundle of fiber filaments contains 1,000 monofilaments. Generally speaking, those with less than 24,000 (24K) carbon fibers are called small tows; those with more than 48,000 (48K) are called large tows. Small tow carbon fiber requires stricter process control and high cost of carbonization equipment. It is mainly used in high-tech fields such as defense and military industries, as well as sporting goods such as aircraft, missiles, rockets, satellites and fishing gear, golf clubs, tennis rackets, etc. ; Large tow carbon fiber has relatively low cost and higher cost performance, and is mainly used in industrial fields such as medical equipment, electromechanical, civil construction, transportation and energy.
Classification by mechanical properties: Because of its excellent mechanical properties, carbon fibers are mostly used as reinforcement materials in application. Therefore, they are more often classified according to their mechanical properties. Tensile strength and modulus are the main standards of the international carbon fiber classification. Can be divided into high strength (GQ), high strength medium model (QZ), high model (GM), high strength high model (QM). China has promulgated the "National Standard for Polyacrylonitrile (PAN) -Based Carbon Fibers (GB / T26752-2011)" on November 13, 2011. As Toray of Japan has an absolute leading advantage in the global carbon fiber industry, Japan's Toray is generally used in China (TORAY) standard for classification.
Carbon fiber composite material industry chain
Because polyacrylonitrile (PAN) -based carbon fiber is the mainstream of current carbon fibers, the following section focuses on the analysis of polyacrylonitrile (PAN) -based carbon fibers.
Carbon fiber industry chain composition
The complete carbon fiber industry chain includes a complete manufacturing process from crude oil to end-use applications: propylene is first produced from fossil fuels such as petroleum, coal, and natural gas, and acrylonitrile is obtained after ammonia oxidation; acrylonitrile is polymerized and spun to obtain polymer Acrylonitrile (PAN) raw silk; carbon fibers can be obtained after pre-oxidation, low temperature and high temperature carbonization; carbon fibers can be made into carbon fiber fabrics and carbon fiber prepregs; carbon fibers can be combined with resins, ceramics and other materials to form carbon fiber composite materials. Various forming processes result in the final product required for downstream applications.
Carbon fiber precursor
For polyacrylonitrile (PAN) -based carbon fibers, the upstream strand preparation technology is the core of its preparation. The strength of carbon fibers depends significantly on the micro-morphology and compactness of the precursor filaments. Quality raw silk is the prerequisite for industrialization and the basis for stable production. Jilin Carbon Valley and Shanghai Petrochemical are heavyweight companies in the field of carbon fiber raw silk. Jilin Carbon Valley commercialized raw silk, and the raw silk business accounted for more than 90% of its total revenue in 2017; Shanghai Petrochemical is a rare domestic company with its own acrylic technology and fully domestic equipment. Technical capability of producing raw silk on the device.
Carbon fiber composites
Carbon fiber composite material is a general term for composite materials with carbon fiber as the reinforcement and resin, metal, ceramic, etc. as the matrix. Common carbon fiber composite materials are mainly resin-based composite materials (CFRP), carbon-based composite materials (C / C), metal-based composite materials (CFRM), ceramic-based composite materials (CFRC), and rubber-based composite materials (CFRR). Among them, resin-based composite materials (CFRP) are the most widely demanded carbon fiber composite materials. The demand in 2017 was 11.87 billion US dollars, accounting for 69.25% of the total demand for carbon fiber composite materials.
Since its introduction in the 1950s, carbon fiber composites are mainly used for advanced science and technology such as rockets, aerospace, and aerospace due to their unique properties. With the continuous improvement and improvement of the properties of carbon fiber composites, they are currently used in aerospace, petrochemical, Transportation, civil engineering, wind power, sports products and other fields are widely used.
Application fields of carbon fiber composite materials
Automotive industry
The material properties and development trends of carbon fiber composites are in line with the development needs of the lightweight automotive industry. Especially with the development of new energy vehicles, carbon fiber composites will be more and more widely used in automobiles. In view of the excellent properties of carbon fiber composite materials, it has gradually begun to be used in foreign automotive interior and exterior trim, chassis and electrical components.
In the future, the application of carbon fiber composite materials and thermoplastic composite materials in the automotive industry will replace traditional metal parts.
Aerospace
Carbon fiber composite materials were first widely used in the aviation industry. In the aviation industry, the light weight of aircraft means that the fuel consumption is reduced, the speed is accelerated, and the characteristics of high strength, low density, and low deformation of carbon fiber determine that carbon fiber is an ideal aviation material. Inside and outside the fuselage of the European Airbus A380, the largest passenger aircraft in the world, the proportion of carbon composite materials exceeds 40%. The cabin inner wall panels, rear fuselage skin, and horizontal stabilizer on the passenger aircraft are made of carbon fiber composite materials; they are called " The "black plane" Boeing 787 passenger aircraft, carbon composite materials account for more than 50% of its total weight, quality is nearly 20% lighter than traditional aluminum alloy body, fuel consumption is greatly reduced, and carbon emissions can be reduced by 2700 tons per year; The carbon composite of C919 is currently only about 20%. The US Super Hornet fighters, the French Rafale fighters and the European Typhoon fighters all use carbon fiber composite materials in large quantities. Carbon fiber composite materials have great application potential in the aviation industry.
Carbon fiber composite materials can reduce the weight of rockets and missiles, increase the range of rockets and missiles, and improve the accuracy of landing points. Carbon fiber composite materials are used in the engine housings of the Tomahawk cruise missiles and Trident-2 missiles of the United States. As early as the 1980s, China successfully adopted carbon fiber composite materials on certain types of sea defense missiles, which increased the missile's range. The camera bracket assembly on the "Tiangong No. 1" uses a carbon fiber composite material developed by Harbin FRP Research Institute. The satellite-expanding solar panels are also mostly made of carbon fiber composite materials. At present, carbon fiber composite materials have also been used as structural stealth materials.
The aerospace industry chose to use carbon fiber composite materials not only because this material can reduce the weight of the fuselage, but also has excellent characteristics such as corrosion resistance and fatigue resistance. However, compared with traditional metal materials, carbon fiber composite materials have not been widely used due to the high cost.
High-speed Train
Carbon fiber composite brake pads are mainly used in high-speed trains and are another important application of carbon fiber composite materials. Japan and France have successfully applied carbon fiber composite brake pads to Shinkansen and TGV high-speed train brakes, and German Knoor Bremse has also developed carbon fiber composite disc brakes for high-speed trains. With the rapid development of high-speed trains in China, carbon fiber composite material brake pads have broad development space.
Marine vessel
In the 1940s, the US Navy first used carbon fiber composite materials for shipbuilding. Thanks to its excellent performance in seawater environments, it is widely used in marine vessels. The design concept of excellent comfort of composite materials and the advantages of seamless hulls have further promoted the development of various composite materials ships.
In recent years, the use of carbon fiber composite materials on ships has been increasing, mainly including hulls, floors, decks, bulkheads, and superstructures such as piping systems and fuel tanks. The application of carbon fiber composite materials not only reduces manufacturing and maintenance costs, improves appearance, but also reduces tonnage and improves safety.
5. Wind power
In the field of wind power generation, composite materials are the main materials for manufacturing wind power generation blades and other important structural components. More than 90% of the blades are composed of composite materials, which can meet the requirements of developing large-scale, lightweight, high-performance, low-cost power generation blades . With the wide application of large tow carbon fibers, the price of carbon fibers continues to decrease, and the application of carbon fibers in large blades has become a trend.
In the manufacture of wind power blades in the future, carbon fiber is used instead of glass fiber in blades, and the amount of carbon fiber is gradually increased is an inevitable result of the development of high-performance carbon fiber composite materials.
6. Sporting goods
Carbon fiber composite materials have also been widely used in sports equipment. Including golf clubs, tennis rackets, skis, fishing rods, bicycle racks, ice hockey rackets, paddles, rowing boats, etc., all have formed mature markets.
7. Petroleum industry
After years of hard work in the United States, the carbon fiber composite continuous sucker rod was successfully developed in the early 1990s. The test results show that the carbon fiber composite continuous sucker rod overcomes the common steel sucker rod's high quality, high energy consumption, and failure times It has many disadvantages, such as large piston effect, slow operating speed and easy to wear. It is a special sucker rod with great development prospects. Recently, China ’s largest oil company, China National Petroleum Corporation, plans to vigorously develop the carbon fiber industry, broaden the application field of carbon fiber composite materials, and continue to extend to high-end markets, especially offshore drilling platforms. At present, each platform uses 80,000 tons of steel. If composite materials are used instead, each platform consumes only 13,000 tons of carbon fiber composite materials. Deep sea oil and gas fields will be an important area where carbon fiber composite materials play a role.
8. Civil Engineering
Cement has the largest amount in the field of civil and building materials, but it also has disadvantages such as high brittleness and low tensile strength. Now carbon fiber reinforced composite materials made of concrete or cement as the matrix overcome the low strength of cement and easy cracking in concrete. It is susceptible to the disadvantages of chloride, sulfate and other erosion. It has a lot of application space in winter and cold areas. In large buildings, the use of steel bars is quite amazing. The amount of steel bars tied up at the National Stadium "Bird's Nest" has reached 52,000 tons. The amount of construction is large, and transportation and installation are time-consuming and labor-intensive. Weight, convenient construction, reduced installation time, and reduced construction cycle. Carbon fiber composite material sheet made of carbon fiber and resin has high tensile modulus and high tensile strength. It is widely used to strengthen damaged reinforced concrete structures. It can greatly improve the impact resistance of oil platform walls when used on oil platforms.