耐超高温碳化硅纤维的制备及机理研究

Precursor procedure up to date is the main strategy to prepare wovenable continuous silicon carbide fibers, which is widely used in high technologies such as aeronautical and aerospace due to its high-temperature resistance in addition to high tensile strength compared to other inorganic fibers. However, ordinary silicon carbide fibers, such as commercial Nicalon, will seriously lose tensile strength at high temperature owning to decomposition and crystalline coarsening, which upsets applications. Therefore, improvement of high-temperature resistance of silicon carbide fibers has become the main trend in this domain.In order to resolve this problem, two independent procedures were employed successfully to promote the high-temperature resistance of silicon carbide. (1) SiC(Al) ceramic fibers were prepared in sequence by synthesis of polyaluminocarbosilane (PACS) using reaction of polycarbosilane (PCS) with Al(AcAc)3, melting spinning of PACS and air-curing followed by ceramicazation. The SiC(Al) ceramic fibers is extremely resistant to high temperature thanks to outstanding sintering aids of aluminum and its inhabitation to growth of SiC crystalline, which densified the fibers and decreased the grain growth while decomposition. (2) SiC(B) ceramic fibers were prepared in sequence by synthesis of BN-PCS-PMS polymer using hybridizing BN-PMS, synthesized by reaction of polymethylsilane (PMS) with borazine, with BN-PCS, synthesized by reaction of PCS with polyborazine PBN), dry-spinning followed by ceramicazation without extra curing step. The SiC(Al) ceramic fibers presented good resistant to high temperature thanks to stoichiometric composition, outstanding sintering aids of boron and its inhabitation to growth of SiC crystalline.The average tensile strength of SiC(Al) and SiC(B) fibers were 1.4GPa and 1.8GPa, with the average diameter 12μm and 13μm, respectively. The initial tensile strength of the both ceramic fibers remained 95% after the treatment at 1400℃ for 1h in argon. After sintering at 1800℃ for 1h in argon, SiC(Al) fibers remained initial tensile strength by 71%; while SiC(B) by 80%. The high temperature stabilities of the two ceramic fibers are better than that of most commercial SiC fibres such as Nicalon NL201, Tyranno (Low M) and Tyranno (ZMI). The high temperature creep resistance of SiC(Al) fibers was much better than that of Nicalon.In our country only ordinary silicon carbide fibers such as Nicalon were prepared and studied, while in Japan super high-temperature resistant silicon carbide fibers were commercialized around 1999. We believed that this project would strongly improve the study level in ilicon carbide fibers of our country, and would greatly close the gap between ours with developed countries.

为了制备当前性能最高的耐超高温碳化硅纤维，采用铝的β-二酮螯合物与聚碳硅烷反应，铣珊琒i-Al-Si-C结构的聚铝碳硅烷。经纺丝、不熔化和烧成，所得纤维可在2200℃下使用？翁庵氐阍谔粞『鲜实尿霞粒芯柯硫衔镉刖厶脊柰榈姆从恚勐撂脊柰榻峁褂胄灾剩宋粘墒钡慕峁棺恋淖饔眉盎硪约白钪障宋慕峁褂胄阅芄叵怠