Oxidation behavior of bulk Ti3SiC2 at intermediate temperatures in dry air

The isothermal oxidation behavior of bulk Ti3SiC2 at intermediate temperatures from 500 to 900 degrees C in flowing dry air was investigated. An anomalous oxidation with higher kinetics at lower temperatures was observed. This phenomenon resulted from the formation of microcracks in the oxide scales at low temperatures. The generation of these microcracks was caused by a phase change in the oxide products, i.e., the trans formation of anatase TiO2 to rutile TiO2. This phase trans formation resulted in tensile stress, which provided the driving force for the formation of the microcracks during oxidation. Despite the existence of microcracks, the intermediate-temperature oxidation of Ti3SiC2 generally obeyed the parabolic rate law and did not exhibit catastrophic destruction due to the fact that cracks occurring in the oxide layers were partially filled with amorphous SiO2. Therefore, further high oxidation kinetics was prevented.