Effect of vacuum heat treatment on electron-beam-irradiation-cured polycarbosilane fibers

Electron-beam-cured polycarbosilane fibers were heat-treated at. 673-1773 K in a tube evacuated to 1.3 x 10(-1) Pa and then exposed at 1873 K in argon , The effect of vacuum heat treatment on improving the high-temperature sta bility of low-oxygen SiC fibers was investigated by examining gas evolution , grain growth, surface composition, tensile strength, and morphology, The fibers heat-treated at <1173 K lost strength, because of the vigorous gener ation of residual hydrogen. A minute amount of oxygen in the atmosphere cau sed the active oxidation of SIC during heat treatment at >1673 K, resulting In severe strength degradation for the as-heat-treated fibers. Vacuum heat treatment at 1573 K provided the best characteristics in low-oxygen SiC fi bers.