Localization of the hottest carbon fiber

2022-08-18
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Localization of carbon fiber

-- Interview with carbon fiber experts, Professor Xu Lianghua of Beijing University of chemical technology, director of Beihua national carbon fiber engineering technology research center, deputy director of Key Laboratory of carbon fiber and functional polymer of the Ministry of education, and director of carbon fiber and composite Research Institute. The invention of T700 grade carbon fiber preparation technology and products with special processes has supported the development of major models in China; Take the lead in realizing the technological breakthrough of T800 high-strength medium modulus carbon fiber, filling the domestic gap; We have successfully developed high-performance carbon fiber localization technologies such as M40J and m55j, and won the second prize of the national science and Technology Progress Award in 2014

q: on May 8, the high technology center of the Ministry of science and technology organized experts to conduct technical acceptance of the 863 project of the Ministry of science and technology, "Research on Key Technologies of graphitization of polyacrylonitrile carbon fiber", because it can be organized in Beihua during the process of machine operation. Please briefly introduce the significance of this project to us

a: this project is mainly aimed at the technology and equipment of Toray m55j high strength and high modulus carbon fiber material. M55j is the main material of the satellite and has always depended on foreign imports. The acceptance of this project is of great significance in two aspects: first, the localization of process technology. From previous experience, the preparation of carbon fiber follows the law of mutual restriction between strength and modulus. If the strength is high, the modulus will decrease, and if the modulus is increased, the strength will decrease. Fibers are from disordered graphite to graphite like, mainly graphite structure, with high modulus and poor strength. How to combine the two structural features is a challenge we face. Since 2010, with the support of the 973 Program of the Ministry of science and technology, we have started to carry out basic science around this problem, and proposed a structural model of high-strength and high modulus carbon fiber. After verifying the rationality of this model through the technical research and development of M40J, we have been using this model to guide our key technology research. The second is the localization of equipment. The key process of high modulus fiber is high-temperature graphitization. The temperature is above 2500 ℃, and the furnace has always been our weakness. In this project, the cooperative enterprise is also very experienced. The furnace is still repeatedly discussed, designed and modified, and finally passed the verification. The technology and equipment have been localized, and their dependence on foreign countries has been reduced. In the face of blockade control, they will not be controlled by others

the highlight of this project is to combine users (Beijing satellite factory) and provide finished products to the application department for verification in time. Domestic carbon fibers have faced such problems. Carbon fibers have excellent properties, but the gap widens after they are prepared into composites, which requires a very long running in period. Compared with m55j, the cost of T300, T700 and T800 is still lower, and the validation period of 3-5 years is still affordable, but the cost of m55j is high, and the expenditure consumption will be very huge for long-term assessment and validation. At the beginning of our project, we integrated users into the subject. After three years, we combined the key processes, equipment and engineering applications. The fibers we made meet the application needs, and the performance of composite structural parts also meet the design requirements, saving time, reducing costs and improving efficiency. This mode of production, learning, research and application cooperation is very worthy of reference

q: at present, PAN based carbon fiber dominates the market. Please briefly introduce the basic research and industrialization of this carbon fiber to us

a: PAN based carbon fibers are called polyacrylonitrile carbon fibers. There are four types of carbon fibers in total, which is one of them and the main one, accounting for about 90% of carbon fiber products. Foreign research began in the 1960s and we started in the 1970s. There is a small gap in this start, but the previous 35 years have been wandering, and only nearly 15 years have witnessed rapid development. Why are you wandering? Is the lack of basic research. Most of the energy of enterprises or research institutes engaged in fiber research is spent on solving engineering problems, and the core basic research is not concerned

we broke through the domestic mainstream technology of dimethyl sulfoxide method in 2000. Before that, we have done basic research for 2-3 years. We regard carbon fiber as polymer material, return to basic scientific problems, follow the objective laws of polymer materials, and simplify complex problems. Since then, we have found the right direction and developed rapidly. In the past 35 years, we have always been exploring. This method and that direction are not good, and the gap with foreign countries is growing. In 2002, we built the first engineering line, and in 2006, we built the first industrialization line in China. Now it has been 18 years, and the gap with foreign countries in key technologies is narrowing

there is still a generation gap in the industry, and the industrial system composed of five parts is not very perfect. By the end of 2017, the theoretical capacity was 26000 tons, including 11 thousand ton lines, 17 100-400 ton lines and 9 500 ton lines. However, our capacity release rate was only 29%, with an international average of 65%, and Toray sometimes reached 70%. The low capacity release rate reflects the relatively low maturity of our industrial technology. The fundamental reason is that the system construction is not perfect, and one of the core issues involved is equipment. China's carbon fiber industrialization equipment starts from the introduction. Domestic digestion, absorption and re innovation are not done well, which leads to the fact that the production process often caters to the equipment, which will lead to problems. When introducing, it is not introduced according to the production line, but according to the device, and it will be assembled and constructed by itself. The supplier ensures that a single equipment meets the technical requirements, and it will not matter whether the industrial line can be built, We don't have more industrialization experience and can't put forward the demand for industrialized equipment that provides high-quality and low-cost biological high molecular variety technology for downstream utilization, resulting in the production capacity of many equipment failing to meet the design goal

domestic equipment such as tens to hundreds of tons can still be made, but there are still many problems with kiloton equipment. The localized manufacturing of carbon fiber industrialization equipment is similar to that of other industries. It mainly depends on experience, and the use of simulation and simulation technology is still lacking, which leads to the unique temperature field and air flow field of carbon fiber production equipment meeting the requirements under static conditions. However, in the dynamic environment of production, the "two fields" fluctuate greatly, which leads to the large fluctuation of the quality of carbon fiber produced. Foreign countries also have certain restrictions on equipment, especially the United States, which will also limit the temperature of equipment. Germany is a little better. It cooperates with Chinese enterprises to produce in China. As long as it is not used for the preparation of high-end carbon fibers, the conditions are relatively loose. The United States requires a license for temperatures above 1800 ℃

I think the main problem of domestic equipment is the lack of design simulation. It may be difficult to implement such reverse thinking as introduction, digestion and imitation, because foreign products are updated faster and their level is improving. For example, pre oxidation equipment requires air circulation. Different fiber varieties and specifications adopt different circulation methods. Because we can't design, we can only rely on the circulation mode of imported equipment, which is more passive. The development of carbon fiber needs to pay attention to equipment, not what people think I can buy with money. The rudiment of Toray equipment is also processed externally, but it will carry out secondary transformation according to its own process, and equipment manufacturers are not allowed to participate. However, there is almost no secondary transformation in China, and imported equipment dare not move. Some enterprises will have a little transformation

observing domestic carbon fiber enterprises, all those with strong equipment ability have done better in industrialization, and vice versa. This phenomenon is obvious, so we advocate that carbon fiber enterprises must have their own equipment capacity, which may take a long time. It is difficult for China to cultivate its own equipment manufacturers. The equipment of the United States and Germany is facing the world and the market is relatively large, while the market of China's equipment manufacturers may only be China. It is difficult for our equipment to go out, and the market is limited after all. Enterprises specializing in equipment are not interested in the field of carbon fiber; Those who are interested in intervention will have high initial investment. Now the cost of an industrialization line is about 150million, and the investment in research and development needs at least 200million. It is difficult to see benefits in the short term. It may need to build dozens of lines to generate returns. There is not such a large market in China, so the situation is more embarrassing. The technology research and development, reserve and condition support of such key strategic materials cannot be supported by market behavior alone

q: what are the challenges for the wide application of domestic carbon fiber in high-end fields? How to achieve high quality and low cost

a: at present, domestic carbon fiber enterprises can ensure the stability of quality in the high-end field. The quality instability we are talking about now is the fluctuation in the use process, that is, the use of technology. First, after the fiber is made into composite materials, the application department will benchmark foreign products. Coupled with the proficiency of foreign fibers, it is qualitatively summarized as not easy to use. In fact, there are still many deep-seated problems to be explored. Second, the strength transfer force is low, and the fiber performance is similar to that of foreign products, but the performance gap of composite materials is relatively obvious. Basically, each type of carbon fiber will encounter these two problems, and these problems are also being explored during the usual discussion. The root cause is that the refinement operation in the fiber preparation process is not enough. Theoretically, each fiber of a bundle of fibers is very regular, but our fibers will cross. It is not completely 0? Arrange, the performance will be reduced, so now let's strengthen the requirements of refined preparation, consider the preparation of fibers from the application end, slowly grasp the pulse of the problem, and the solution should be faster

in 2002, there were only three domestic R & D units engaged in carbon fiber, including Shanda, Beihua, Shanxi Coal Chemical Institute, and Donghua University, but they mainly made gel carbon fiber. In 2008, I assisted in the construction of the carbon fiber Laboratory of Ningbo Institute of materials, Chinese Academy of Sciences, with four research units. Up to now, less than 4 companies have really done complete key technology research, from which it is not difficult to find that the R & D force is shrinking. I often think about this problem and have put forward written suggestions. Our basic research needs to be strengthened, and the R & D team needs to be expanded. There are 3-5 R & D units. Moderate competition and cooperation interaction is a good thing. If we develop exclusively, the direction may go astray. Our R & D achievements are being industrialized, but I don't do industrialization myself. Instead, I focus on technology research and development. After all, my energy is limited. Carbon fiber is a very complex material. The laboratory also has the characteristics of industrialization. It is a reduced version of the industrial line. Without 3-5 years of in-depth research, it is difficult to get started

the cost of domestic carbon fiber is relatively high. We believe that it is not simply an economic problem, but a deep-seated technical problem. The high cost of energy and equipment is only one factor, more technical factors. The production capacity is not released, the equipment and technology are not qualified, the proportion of sizing agent is high, the fiber qualification rate is low, and the quality cannot meet the application requirements are all technical problems. High quality and low cost can be achieved through reasonable technical means. For carbon fiber, we propose to strive to achieve a price of $10/kg by 2030; Some time ago, Chinese experts from Boeing visited, and they mentioned

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