Silicon carbide fibers from copolymers of commercial polycarbosilane and silazane

Abstract

A new approach to prepare silicon carbide fibers by a non-oxidative chemical crosslinking of a commercial, low molecular weight polycarbosilane via copolymerization with vinyl silazane monomer was investigated. Dicumyl peroxide was used as an initiator for copolymerization reactions. SiC fibers were produced by pyrolyzing the spun polymer fibers at 1000°C without any additional curing process. The ceramic yield upon pyrolysis was 65-70%. According to neutron activation analysis, the oxygen content of our copolymer- derived SiC fibers was less than 3 wt%. The tensile strength of our SiC fibers increased slightly after 1400°C heat-treatment while it dropped greatly after 1500°C treatment.