The mechanism of pyrolysis of Si-Ti-C-O amorphous fiber (Tyranno) was studied. The pyrolytic rate was measured by means of a thermo-balance in Ar stream at temperatures from 1473K to 1673K. The pyrolysis products were examined by X-ray diffraction and SEM observation.
The pyrolytic rate was strongly dependent on temperature, and the amorphous fiber crystallized to β-SiC and TiC during the pyrolysis. The pyrolysis rate was determined by the crystal growth controlled by the diffusion of carbon in the fiber and described by an Avrami-Erofeev equation. Tyranno fiber decomposed more rapidly than Ti free Nicalon fiber.