Development of Long-length Silicon Carbide Fiber for Ceramic Composite Material, having Super High Fracture Toughness

（1）由于公知的以有机硅化合物为前体的长的无定形SiC纤维具有有限的耐热温度，因此通过长的碳纤维和SiO之间在几个减压下的反应来进行基本上不同的方法，以制备多晶结构。只有在反应压力为-76cmHg（表压）的情况下，才能得到柔软、柔韧的纤维，扫描电镜（SEM）显示纤维具有独特的截面结构。(2)It然而，发现这样获得的纤维显示出差的机械强度，这表明在成形工艺如FW（长丝缠绕）中存在困难。因此，本研究的最初目的，不得不转向利用上述结论来提高碳纤维抗氧化性能的途径。结果表明，B-SiC涂层碳纤维在1400 ℃、-76cmHg（表压）下仅需几分钟即可保持足够的强度。与未涂覆碳纤维中观察到的400 ° C相比，发现通过空气氧化损失2重量%的温度升高超过100 ° C。

(1)Since the long-length, amorphous SiC fiber being well-known, started from an organo-silicon compound as its precursor, has a limited heat-proof-temperature, a basically different approach was carried out by the reaction between long-length carbon fibres and SiO under several reduced pressures in order to prepare a polycrystalline structure. Only in the case of the pressure of -76cmHg(gauge)during the reaction, a soft and flexible fiber was obtained, which showed a unique sectional structure in SEM(Scanning Electron Microscopy).(2)It was, however, found that the fiber thus obtained showed a poor mechanical strength, suggesting a difficulty in the forming process such as FW(filament winding). Then, the initial purpose of this research was obliged to change to an approach to improve the resistivity of carbon fibres vs.oxidation by making use of above obtained conclusion. As a result, B-SiC coated- carbon fibres remaining enough strength was obtained at 1400ﾟC for only a few minutes under -76cmHg(gauge). The temperature where 2 wt-% was lost by air-oxidation, was found to be raised over 100ﾟC comparing with 400ﾟC observed in non-coated carbon fiber.