Oxidation Behavior of Titanium Boride at Elevated Temperatures

The oxidation behavior of dense TiB 2 specimens was investigated. Hot‐pressed TiB 2 with 2.5 wt% Si 3 N 4 as a sintering aid was exposed to air at temperatures between 800° and 1200°C for up to 10 h. The TiB 2 exhibited two distinct oxidation behaviors depending on the temperature. At temperatures below 1000°C, parabolic weight gains were observed as a result of the formation of TiO 2 ( s ) and B 2 O 3 ( l ) on the surface. The oxidation layer comprised two layers: an inner layer of crystalline TiO 2 and an outer layer mainly composed of B 2 O 3 . When the oxidation temperatures were higher than 1000°C, gaseous B 2 O 3 was formed along with crystalline TiO 2 by the oxidation process. In this case, the surface was covered with large TiO 2 grains imbedded in a highly textured small TiO 2 matrix.