High temperature oxidation behavior of quaternary ordered (Cr2/3Ti1/3)3AlC2-based MAX ceramic

High temperature oxidation behaviors of (Cr2/3Ti1/3)3AlC2-based ceramic at 800−1300 °C in air were studied. The parabolic oxidation rate constants were 3.9 × 10−13 and 1.6 × 10-11 kg2 m-4 s-1 at 800 and 900 °C, respectively. Above 900 °C, deviation of parabolic oxidation law was observed. During high temperature oxidation, the oxides of Cr2O3, (Cr,Al)2O3 and rutile TiO2 were produced, while Cr2TiO5 and (Cr0.222Ti0.778)O1.889 appeared at above 1000 °C. It was revealed that (Cr2/3Ti1/3)3AlC2 decomposed into Cr2AlC and TiC during oxidation process. The oxidation mechanism was proposed according to the evolution process of both phase composition and microstructure of oxides.