General Secretary Xi Jinping pointed out: "The new material industry is a strategic and basic industry, and it is also a key area of high-tech competition. We must catch up and catch up." The development and application of new materials can promote technological progress and industrial upgrading, and even promote human society to a new level. For example, semiconductor materials have brought us into the information society.

Looking at the world, new breakthroughs have been made in materials science research, and a number of new materials, such as iron and steel materials, non-ferrous metal materials, petrochemical and chemical materials, have emerged one after another, injecting strong momentum into the manufacturing industry and economic and social development. Carbon fiber is one of the most widely used new materials.

A bicycle frame made of carbon fiber weighs only about 600 grams, equivalent to three apples. A 1-meter-long T1000 grade carbon fiber, a bundle of thick fingers and weighing only 0.5 grams, can pull two civil airliners. Carbon fiber products can be safe and sound at 3000 degrees Celsius, can be used in acid, alkali, oil, salt and other corrosive environments ...... Carbon fiber has high strength, high modulus, high temperature resistance, corrosion resistance, light weight and many other excellent properties, in the modern manufacturing industry has broad application prospects, known as "industrial black gold".

Thin as hair, light as a feather, stronger than steel

Carbon fiber is a kind of inorganic fiber with carbon content above 95%, which is made of different raw materials by polymerization, spinning, oxidation and high temperature carbonization. According to the type of raw materials, carbon fiber mainly has polyacrylonitrile-based carbon fiber, viscose-based carbon fiber and pitch-based carbon fiber 3 kinds. Among them, the petrochemical product acrylonitrile as the main raw material of polyacrylonitrile-based carbon fiber, accounting for more than 90% of the world's total carbon fiber output, is the main source of high-performance carbon fiber.

Carbon fiber has excellent properties such as fine hair, light as a feather, and stronger than steel. The diameter of carbon fiber is usually 5-7 microns, only about 1/10 of the thickness of the hair, and the density is small, generally 1/5 of steel, 2/5 of titanium, and 3/5 of aluminum. Although the body is light and thin, the strength of carbon fiber is very high, generally 35 times that of steel. In practical applications, a certain number of carbon fiber "filaments" are usually wound up like braid ropes. A standard 12K (I .e. 12000) carbon fiber is less than a pencil thick, but it can bear a weight of about 130kg. At the same time, carbon fiber can be safe and sound at a high temperature of 3000 degrees Celsius, between minus 100 degrees Celsius and 100 degrees Celsius, its size remains basically the same, and can be used in a highly corrosive environment, which can be described as "real gold is not afraid of fire".

It is not easy to obtain such characteristics. The preparation process of carbon fiber is long, the process is complex, and the difficulty is comparable to that of chip and micro-nano lithography. The carbon fiber preparation process includes hundreds of subdivision processes, involving polymer chemistry, polymer physics, materials science, polymer processing and spinning engineering, industrial automation control, high temperature engineering, etc., with thousands of process control points and more than 10,000 process parameters, and changes in each parameter will affect the final performance of carbon fiber. At present, the world's most advanced chip lithography technology reaches a few nanometers. Similarly, high-performance carbon fiber also requires carbon fiber internal defects to be controlled within 10 nanometers. Carbon fiber has to go through high temperature carbonization from ordinary room temperature to 1700 degrees Celsius or even 2500 degrees Celsius, and the temperature accuracy should be controlled at 5-10 degrees Celsius, which shows the difficulty. It can be said that each bundle of carbon fiber material is tempered. Because of the high technical requirements and difficulty in manufacturing, the price of carbon fiber is relatively expensive. The price of aerospace-grade carbon fiber is between thousands of yuan and 10,000 yuan per kilogram, which is dozens of times the price of steel and aluminum alloy, but carbon fiber, with its excellent performance, is still an indispensable key material for the national economy and national defense construction.

SUPPORT MATERIALS OF MODERN MANUFACTURING

Carbon fibers combine the high strength of carbon materials with the soft workability of fibrous textile materials. A bunch of finger-thick high-strength carbon fiber can pull the plane. Carbon fiber can also be woven into fiber cloth, woven and cut into specific shapes as needed, and cured by resin to become a material with higher strength than high-strength steel. Because of its many excellent characteristics, carbon fiber is widely used and has become an important supporting material in the fields of aerospace, electric power, transportation and other high-end equipment, major basic engineering, new energy and so on.

In the field of aerospace, the amount of carbon fiber is often used as an important indicator to measure the level of aerospace equipment. Carbon fiber composite materials can be used in the manufacture of aircraft, satellites, rockets, etc., and can also help products reduce noise and save fuel. For example, civil airliners use carbon fiber composite blades, the weight of which is more than 500 kilograms less than traditional titanium alloys, the overall weight of the fuselage is reduced by 1 ton, the fuel consumption of the aircraft is greatly reduced, and the range is effectively improved. The addition of carbon fiber to propellants and propellants can also improve the mechanical properties of propellants, increase the burning rate of propellants and improve the combustion performance of propellants.

In the field of automobiles and wind power, which are closely related to people's livelihood, carbon fiber has become a sharp weapon to improve performance. Carbon fiber composite materials have low density, light weight, high rigidity, and high suction. The energy absorption capacity of the material during collision is 6 to 7 times higher than that of steel structures. The use of carbon fiber composite materials in automobile manufacturing can greatly improve the acceleration performance, braking performance, shock absorption performance, and safety performance of automobiles. For example, in high-end precision Formula One racing cars, all models without exception use carbon fiber reinforced polymer matrix composite materials to manufacture the frame, body, chassis, etc., reducing the mass of the body by 40% to 60%, which is equivalent to 1/3 of the mass of the steel structure. To 1/6, it also maintains sufficient strength and rigidity. Based on carbon fiber materials, some car manufacturers have produced super sports cars with a body weight of less than 300kg.

In terms of wind power equipment, the blade girder is the use of carbon fiber composite materials. The length of these main girders is often more than 70 meters or even 120 meters. The use of large tow carbon fiber for manufacturing can significantly reduce the weight of the blade, increase the stiffness of the blade, greatly improve the cost performance of the product, and improve the power generation efficiency and stability of the whole unit.

In sports equipment manufacturing, carbon fiber can also show their skills. At present, the use of carbon fiber for high-end sports equipment manufacturing can help athletes break the limit and create new records. For example, in the manufacture of tennis rackets, bicycles, golf clubs, skis and kayaks, giving full play to the advantages of light weight of carbon fiber materials can reduce the "burden" of athletes ". Compared with aluminum rackets, tennis rackets made of carbon fiber can increase the maximum ball speed by 20% to 250 km/h. In the future, as technology improves and costs decrease, there will be more sportswear with carbon fiber.

Combination of production, teaching and research to strengthen the carbon fiber industry

Since the beginning of the new century, China has organized superior scientific and technological forces to tackle key problems in carbon fiber science and technology. After more than 20 years of unremitting efforts, breakthroughs have been made in the engineering, industrialization and localization of carbon fiber. In August this year, the domestic T1000 grade polyacrylonitrile-based carbon fiber thousand-ton industrial production technology passed the technical appraisal of the expert committee. Immediately afterwards, the country's first 10,000-ton high-performance carbon fiber production base was built in Xining. China's carbon fiber industry has grown from scratch, from large to large, from large to excellent, the technical level and industrialization development momentum is good, and the research and application has entered a new stage of rapid development.

In this highly integrated production field, providing the market with a wide range of products with stable quality, sufficient output and reasonable price is the key to the iterative upgrade of carbon fiber technology. According to internationally accepted standards, carbon fiber products will be divided into different models according to strength and modulus, such as high-strength, high-modulus, high-strength medium-modulus, high-strength high-modulus and other series, of which high-strength series are divided into T300, T800, T1000 and other models according to tensile strength. Different carbon fiber products in the application field are like scientific research topics that need to be broken one by one. Even the lowest grade of T300 carbon fiber, the strength is several times that of the general car anti-collision beam, the difficulty of research and development can be imagined. With the joint support of software and hardware technologies such as molecular design, polymerization engineering, solidification molding, and equipment refinement control, my country has successively broken through T300, T700, and T800 grade polyacrylonitrile-based carbon fiber during the "Tenth Five-Year Plan" period. Key technologies to achieve large-scale production. In 2022, China's carbon fiber production has accounted for 1/3 of the world.

The output has gone up, and the production of ultra-high-performance carbon fiber also urgently needs us to "climb to the top" to achieve large-scale and stable production. T1000 grade carbon fiber is one of the highest strength carbon fiber series in the world. Domestic carbon fiber production enterprises and Shenzhen University collaborative research, to overcome this technology. After testing by domestic authoritative institutions, this kind of carbon fiber products are prepared on the production line with an annual output of 1700 tons, and the performance reaches the international product level, and the product quality qualification rate is higher than 95%. With the steady progress of production, T1000 grade carbon fiber materials will help meet the growing urgent needs of China's high-end industrial fields.

Under the dual promotion of policy and market, China's carbon fiber technology has been continuously improved, and the carbon fiber industry chain has gradually improved. From catching up and catching up to making persistent efforts and climbing the peak bravely, carbon fiber technology will contribute a more solid and powerful "Chinese strength" on the way to achieving high-level scientific and technological self-reliance ".