Fig. 3-6 Extremely heat-resistant SiC fiber fabricated by the electron beam technique

Fig. 3-7 SiC fiber synthesized by our electron beam method shows good heat-resistance compared with the usual thermal-oxidation method.

It is generally expected that composite materials to be used as equipment parts at high temperatures can be synthesized by reinforcing metals or ceramics with silicone carbide (SiC) fiber. Such attempts have been successful only at temperatures below 1200 degrees cent., mainly because of the remaining oxygen in the SiC fiber which causes decomposition of the fiber. JAERI has developed a new technique for producing SiC fiber which can be used at temperatures as high as 1700 degrees cent.: Polycarbosilane fiber is irradiated in a helium atmosphere with electron beams. The irradiation produces cross-linkings between carbosilane polymers and makes them suitable to fabricate SiC fiber with less oxygen content. Moreover, we have found that polycarbosilane fiber, irradiated in oxygen followed by heat treatment, gives soft and strong SiC fibers. Also, irradiation in helium followed by heat treatment in ammonia gas flow produces SiN fiber, which is white in color and electrically insulating. These fibers are expected to be used as light, heat-resistant and strong materials for parts of a spacecraft and a fusion reactor.

Reference T. Seguchi et al., Heat Resistant SiC-Fiber Synthesis and Reaction Mechanisms from Radiation-Cured Polycarbosilane Fiber, Proc. 6th European Conference on Composite Materials (September 1993, Bordeaux) 51.

Select a topic in left column