Oxidation behavior of titanium boride at elevated temperatures

The oxidation behavior of dense TiB2 specimens was investigated. Hot-pressed TIB2 with 2.5 wt% Si3N4 as a sintering aid was exposed to air at temperatures between 800 degrees and 1200 degreesC for up to 10 h, The TIE, exhibited two distinct oxidation behaviors depending on the temperature. At temperatures below 1000 degreesC, parabolic weight gains were observed as a result of the formation of TiO2(s) and B2O3(l) on the surface. The oxidation layer comprised two layers: an inner layer of crystalline TiO2 and an outer layer mainly composed of B2O3 When the oxidation temperatures were higher than 1000 degreesC, gaseous B2O3 was formed along with crystalline TiO2 by the oxidation process, In this ease, the surface was covered with large TiO2 grains imbedded in a highly textured small TiO2 matrix.