Improvement in oxidation resistance of TiB2 by formation of protective SiO2 layer on surface

Abstract

To improve the oxidation resistance of TiB2 material, dense silica (SiO2) layer was caused to form on the surface. The coating layer was formed on the surface by exposing the specimens next to a bed of SiC powder in a flowing H2 containing 0.1% H2O at 1450 °C. Part of SiO2 “smoke”, generated by a reaction between the SiC powder and H2O in the H2 gas stream, was deposited on the sample surface to form a dense and uniform SiO2 layer. Beneath the SiO2 layer, an interfacial layer composed of Ti2O3 and B2O3was formed. Oxidation resistance of the specimen was improved markedly by the coating layers. The coating layers enhanced the oxidation resistance through the retardation of oxygen transport and also through the consumption of oxygen by a reaction with Ti2O3 to form TiO2.