High-temperature decomposition of low-oxygen SiC fiber under N sub 2 atmosphere

• Published in: Nihon Seramikkusu Kyōkai gakujutsu ronbunshi Vol. 102; pp. 1142 - 1147
• Main Authors: Shimoo, T, Hayatsu, T, Takeda, M, Ichikawa, H, Seguchi, T, Okamura, K
• Format: Journal Article
• Language: Japanese
• Published: 01.12.1994
• ISSN: 0914-5400

The pyrolysis of a low-oxygen SiC fiber, prepared by the electron-irradiation curing method, has been investigated in N sub 2 atmosphere at temperatures from 1673-1973K. Then, the pyrolytic behavior in N sub 2 was compared with that in Ar. The fiber absorbed a considerable amount of nitrogen, and consequently, the mass loss caused by the pyrolysis was compensated. While the nitrided layer retarded the crystallization into beta -SiC < 1773K, this effect disappeared > 1873K. As a result of the reaction of SiO with carbon, coarse SiC particles grew on the surface of the fiber heat-treated at 1973K. The tensile strength of the fiber was inversely proportional to the square root of the SiC crystal size. For SiC crystals with the same size, the strength was much higher in N sub 2 than in Ar, because of smoothness of the surface.