Pyrolysis of low oxygen SiC fiber prepared by electron-irradiation curing method

Abstract

The pyrolysis of the low oxygen (1.7%O) SiC fiber prepared by the electron-irradiation curing method has been investigated. The pyrolytic rate was measured with a thermobalance in Ar at temperature from 1673 to 1973 K. The pyrolyzed fiber was examined by X-ray diffraction, SEM observation, specific resistance measurement and tensile test. Lowering of oxygen content in the fiber was found to be effective for the suppression of pyrolysis. The pyrolyzed fiber was composed of β-SiC and amorphous carbon. The growth and coarsening of SiC crystals was observed on the skin of the fiber, while the core was smooth and remained in the microcrystalline state. The tensile strength of the fiber, which was heated at 1973 K for 3.6 ks, retained 34% of that of the original fiber. The strength was correlated closely with the size of the β-SiC crystal in the fiber.