Abstract
Low-oxygen-content Si-C fibers (Hi-Nicalon) with 0.5 wt% oxygen were prepared from polycarbosilane with electron beam irradiation curing and pyrolysis. The thermal stability of the Hi-Nicalon fibers was significantly improved compared to Si-C-O fiber (Nicalon) with 12 wt% oxygen. However, creep deformation occurred in the Hi-Nicalon fiber at high temperatures, caused by SiC micro crystals and amorphous carbon. Then, stoichiometric and highly crystalline SiC fiber (Hi-Nicalon type S) was prepared from EB irradiation cured fiber by pyrolysis in a hydrogen gas flow. Type S fibers had high tensile modulus, excellent thermal stability, and creep resistance at high temperature. Hi-Nicalon and Hi-Nicalon type S fiber appear to be the best candidates for the reinforcement of ceramic matrix composites.
