KINETICS AND MECHANISM OF THE OXIDATION OF ZRC

The oxidation behaviour of sintered ZrC powder was studied under iso- and non-isothermal heating conditions under varied oxygen pressures fr om 5 to 50 kPa and the weight changes during the reaction were followe d by thermogravimetry. The sample ignited under an oxygen pressure of 101.3 kPa when heated non-isothermally at 5 K min-1. The end product w as identified by X-ray diffraction as cubic ZrO2 at temperatures below 1073 K and monoclinic above that. The rate of the reaction was found to be diffusion controlled. The mechanism of the reaction was discusse d in terms of the diffusion of oxygen through the product layer.