Improvement of intermediate-temperature oxidation resistance of Ti3AlC2 by pre-oxidation at high temperatures

Ti3AlC2 has good oxidation resistance at high temperatures owing to the formation of protective Al2O3 layer. However, as it is directly exposed to air at 500 degreesC and especially 600 degreesC, the scales formed on Ti3AlC2 exhibits poor protectivity because of the oxidation-induced microcracks, which limits the potential application of this technologically important material. In this work, the oxidation resistance of Ti3AlC2 at 500 degreesC and 600 degreesC was significantly improved by pre-oxidation at 1000-1300 degreesC for a short time of 2 h in air. The oxidation of the pre-oxidized Ti3AlC2 at 600 degreesC generally obeyed a parabolic rate law instead of the speed-up linear relation in the case without pre-oxidation. As revealed by X-ray diffraction, Raman spectroscopy results and SEM observations, the remarkable improvement of oxidation resistance after pre-oxidation was attributed to the protective layers formed on Ti3AlC2 during pre-oxidation, which inhibited the formation of anatase TiO2 that resulted in the oxidation-induced microcracks. Moreover, this work confirmed that the mechanism proposed previously for the anomalous oxidation of Ti3AlC2 in air at 500-600 degreesC was correct.