Oxidation kinetics of low-oxygen silicon carbide fiber

The effect of partial pressure and temperature on the oxidation rate of low -oxygen silicon carbide fiber (Hi-Nicalon) has been investigated. The initi al oxidation rate was described by a two-dimensional disc contracting formu la for reaction control, and the activation energy was 155 kJ/mol. The rate at the later stage of oxidation obeyed the equation for diffusion control, and the activation energy was 109 kJ/mol. Both the rate constants were pro portional to oxygen partial pressure. The diffusion species through the SiO 2 film are considered to be oxygen molecules. (C) 2000 Kluwer Academic Publ ishers.