Ningbo pioneer in silicon carbide material system for technical progress
silicon carbide ( 原文如此) Fiber is the carbon fiber after the development of a high performance ceramic fibers, it has high strength, high modulus, resistance to chemical corrosion, high temperature resistance, oxidation resistance and creep properties. In the aspect of application, SiC fiber and ceramic substrate with good compatibility, it is important to high performance reinforced ceramic matrix composites. At present, SiC fiber reinforced ceramic matrix composites have been applied in aerospace engine heat resistant parts, reusable vehicle thermal protection materials, transport of hypersonic propulsion system, nuclear reactor materials. In addition, it also in the high temperature sintering furnace for heating rods, metallurgy pyrocarbon set, high speed brake discs, gas turbine hot end components, high temperature gas filtration and heat exchanger etc has application value.
the preparation method of the SiC fiber are: organic precursor body reforming process, chemical vapor deposition process and activated carbon fiber and super fine powder sintering, catalysis, etc. Organic precursor body reforming process is based on organic polymer pioneer body, using its soluble or fusible properties after molding, high-temperature processing, from organic to inorganic ceramic material. Compared with other methods, the organic precursor body reforming process of preparing SiC fiber has significant advantages, including: ( 1) Through molecular design, can control the composition of organic precursor body, thereby gaining SiC fibers with different functions or improve the performance of the SiC fiber; ( 2) Easy to shape, suitable for preparation of small diameter continuous SiC fiber; ( 3) High production efficiency and lower cost. Japan and the United States based on organic precursor body reforming process developed is an international leading position, the strength of the SiC fiber are mainly Japanese Nippon Carbon company development of SiC fiber Nicalon series, Japan's Ube Industries, the development of Tyranno series of SiC fibers and the COI ceramics company developed Sylramic series of SiC fibers.
in the late 1970 s, China began reforming process was developed based on organic precursor body own SiC fibers. However, compared with the international high performance technical index of the SiC fiber, the current is still a big gap. In terms of production, according to incomplete statistics, at present, the global output of 300 tons, a continuous SiC fiber yield the largest is the Japanese Nippon Carbon company and Ube Industries company, achieves 120 tons/year, and the output of our country accounts for about 1% of the world, even can't meet the domestic market, and the serious influence to our country in the development of SiC fiber reinforced ceramic matrix composites. For our country, therefore, high performance of SiC fibers and enhance the preparation of ceramic matrix composites and production is imminent. In view of the SiC fiber and its reinforced ceramic matrix composites in the field of nuclear energy and aerospace high-tech strategic status, the United States and Japan to monopoly policy, and technology of our country. In order to promote the development of nuclear energy, aerospace, and other important areas, must speed up the high performance of SiC fibers and enhance the development of ceramic matrix composites. Under this background, the special fiber by ningbo material department of Chinese Academy of Sciences, special fiber and nuclear materials engineering laboratory was carried out by SiC fiber and SiC fiber reinforced SiC ceramic matrix composites key preparation technology development work. The work for major research projects of national natural science fund, the forerunner of the Chinese Academy of Sciences project support, etc.
the SiC organic precursor body is affecting SiC fiber and SiC of SiC fiber reinforced ceramic matrix composites preparation technology and properties of one of the key factors, in 2015, pioneer in SiC organic system aspect, the team has achieved the following results:
1, the successful preparation of poly silane ( 经前综合症) : in order to solve the problem of difficult PMS source, the team has carried out the development of the PMS. In two and a half months time, complete reaction conditions to explore, test equipment procurement and successful preparation of kg and quality qualified PMS, meet the demand for raw materials of the project operation, and formed the technology of the preparation of engineering.
2, the use of the PMS successfully synthesized carbon silane ( PCS) : PCS is an important organic precursor, SiC fiber through groping process conditions on the size and molecular weight distribution of PCS, effects of softening point and spinnability of research; Design and manufacture of the PCS pilot synthesis device, in the process of installation, debugging, solve the equipment configuration and temperature control problem; At present, the project team was prepared using pilot synthesizer kg good spinnability of PCS, and successfully spun out of the continuous length of more than 20000 meters of the SiC fiber strand.
3, solve some liquid hyperbranched poly (carbon silane ( LHBPCS) The preparation technology of: LHBPCS as the pioneer of the SiC ceramic substrate, because have good liquidity, but since the crosslinking, ceramic yield high and close to the pyrolysis products advantages of SiC stoichiometric ratio and attention. Project team successfully synthesized some LHBPCS, ongoing pilot enlarge synthesis.
the team in SiC fiber organic precursor body and SiC ceramic substrate preceramic polymer results for the next step of the SiC fiber engineering preparation and SiC of SiC fiber reinforced ceramic matrix composites preparation and research laid a solid foundation.