Reaction Mechanisms of Silicon Carbide Fiber Synthesis by Heat Treatment of Polycarbosilane Fibers Cured by Radiation: I, Evolved Gas Analysis.

Abstract

SiC fibers were synthesized from polycarbosilane (PCS) fibers by heat treatment after electron beam irradiation curing. The pyrolysis reaction mechanisms from the organic PCS to ceramic SiC were investigated by the analysis of gases evolved during heat treatment. There were two steps in the major reaction: the first step was at 800–1200 K where H 2 and CH 4 evolved by scission of Si‐CH 3 and Si‐H and by rearrangement reactions, and the second step was at 1000–1700 K where H 2 evolved by reactions related to C atoms in the PCS main chain. H 2 evolution in the first step was reduced with increasing oxygen content in the cured PCS fibers.