Source: China News Network
Xining, August 29 (Reporter Song Yusheng) Airplanes, wind power blades, cable-stayed bridges, professional bicycles, badminton rackets... These seemingly unrelated things will actually use the same new material - carbon fiber.
There is a complex technical process behind this high-quality material. Conquer core technologies, there are no tricks and shortcuts. In the face of foreign technology blockade, in order to take off carbon fiber, the "crown jewel of materials", Chinese has experienced a difficult research and development process.
"The crown jewel of materials"
"Carbon fiber is an amazing material." According to Luo Haoyu, Secretary of the Party Committee and Deputy General Manager of China National Building Materials Group, materials are the foundation of manufacturing, and carbon fiber related products are widely used in aerospace, wind turbine blades, sports and leisure, pressure vessels, carbon/carbon composite materials, transportation construction and other fields, and its importance is self-evident.
The reason why it is so widely used is related to the characteristics of carbon fiber.
The picture shows the high temperature resistance test of carbon fiber. Photo by Li Taiyuan
Carbon fiber has excellent mechanical properties and chemical stability, lower density than aluminum, higher strength than steel, corrosion resistance than stainless steel, and is the fiber with the highest specific strength and the highest specific modulus among the high-performance fibers that have been mass-produced.
A 1-meter-long bundle of SYT65 (T1000 grade) carbon fiber weighs only 0.5 grams, but its strength can withstand a force of about 500 kilograms. A bunch of carbon fiber with the thickness of a finger can pull two planes.
The picture shows the corrosion test of carbon fiber in aqua regia. Carbon fiber (left) does not react in aqua regia at all, iron wire (right) has corrosion reaction. Photo by Li Taiyuan
In addition, the ultra-light bicycle frame made of carbon fiber can be lifted with only two fingers; Even if carbon fiber is put into the highly corrosive "aqua regia", it is "calm", and it is difficult to observe a significant reaction with the naked eye.
The picture shows an ultra-light carbon fiber bike rack that girls can lift with two fingers. Photo by Li Taiyuan
Corresponding to such high-quality properties is the complex production process of carbon fiber.
According to public information, the production of carbon fiber must go through hundreds of processes, more than 300 key technologies, more than 3,000 process parameters, and the integration of more than ten systems to complete. For this reason, carbon fiber is also known as the "crown jewel of materials".
"'Burn' a Santana in one day"
In order to take off this "crown jewel of materials", the researchers went through a difficult research and development process.
The research and development of carbon fiber in mainland China began in the early 60s of the 20th century, but the key core technology has not made breakthroughs for many years, resulting in heavy dependence on imports for related products.
On the other hand, the "carbon fiber power" that masters the core technology implements a three-way blockade of "technology, equipment and products" for the carbon fiber needed by the mainland. Chinese R&D personnel had to "find another way".
In September 2005, Zhongfu Shenying officially launched the carbon fiber project, and since then it has successively conquered the key technologies of the whole process such as high-temperature drafting machine, wet spinning process 100-ton thread, 1000-ton wire precursor preparation and carbonization process. In 2007, the first batch of carbon fiber industrialized by Zhongfu Shenying rolled off the production line; In 2008, it built a 1,000-ton SYT35 (T300 grade) carbon fiber production line.
From 2006 to 2012, Zhongfu Shenying was mainly engaged in the research and development and production of wet process T300 carbon fiber, and built a 1,000-ton SYT35 (T300 grade) carbon fiber production line and achieved stable production.
However, "upgrading" from T300 carbon fiber to SYT65 (T1000 grade) carbon fiber is far less easy than expected. Even, the company "burns" a Santana every day at the height of R&D.
Lian Feng, general manager of China National Building Materials Zhongfu Shenying Xining Company, told reporters that during this period, the company's annual investment reached "hundreds of thousands". "Because we invested a lot of R&D expenses in the early stage and there were no new products, this was the 'darkest period' of our development, and we were losing money every day."
After countless failures, in 2008, Zhongfu Shenying thousand-ton carbon fiber production line was officially put into operation. In 2012, Zhongfu Shenying's first dry-spray wet spinning 1,000-ton T700 production line was completed and put into operation, becoming the largest and most technologically advanced high-end carbon fiber production line in China at that time. In 2018, the project of "Key Technologies and Applications of Industrialization of Dry Spray Wet Spinning 1,000-ton High-strength/100-ton Medium Model Carbon Fiber" led by Zhongfu Shenying won the first prize of National Science and Technology Progress Award.
Chinese used the world's most advanced dry spray wet spinning technology to successfully make "Chinese carbon fiber".
The picture shows the carbon fiber production line. Photo by Li Taiyuan
"One innovation" drives "N family renewal"
"It's easy to say now, but it was really hard at the time." Zhang Guoliang, chairman of Zhongfu Shenying, once sighed with such feelings.
"For example, the spinning liquid has to pass through the air layer, and the most difficult part of this link is how to quickly pull the spinning liquid through the water in such a short time. After the spinning liquid enters the water, it has no strength itself, but it needs to be pulled forward at a very fast speed, and it must form strength immediately. What to do? It depends on the temperature. Just trying this temperature, we tried it countless times at that time, and finally we succeeded. Another example is the spinning speed, under the dry spray wet spinning process, which means that we have to increase the spinning speed from the previous 70 m/min-80m/min to 400m/min, and this technical difficulty is even more imaginable. It can be said that the theoretical model of this process is summarized step by step and established little by little. He said.
From the initial gradual attempt in technology, to the current 10,000-ton carbon fiber base has been put into production. Raw material enterprises overcome the core technology, and all kinds of downstream production enterprises can take new materials to make new products, realizing "one innovation" to drive "N family renewal".
In September 2021, Zhongfu Shenying Xining 10,000-ton carbon fiber base in Xining, Qinghai Province was put into operation, which is also the world's highest high-performance carbon fiber production base; When fully operational, the site will become the world's only high-performance carbon fiber production base with a scale of more than 20,000 tons.
The picture shows the finished carbon fiber. Photo by Li Taiyuan
Lian Feng said bluntly, "This is not only our response to market demand, but also the group's strategic deployment in the field of new materials, that is, to expand and strengthen the new materials industry chain." ”
He introduced that at present, the base mainly produces a series of products of T700, T800 and T1000. "After these products are supplied to the market in large quantities, they can further meet the application of domestic aerospace, wind, solar, hydrogen, new energy and many other fields, and also ensure the independent production capacity of carbon fiber in our country, and realize the localization of materials in key fields."
It is understood that at present, the headquarters of Zhongfu Shenying Lianyungang has achieved the successful preparation of T1100-grade carbon fiber.