Preparation of Cr2AlC powder and its isothermal oxidation behavior in dry air and pure steam

Abstract

As a promising candidate ceramic for using in harsh environments, Cr2AlC ternary carbide possesses numerous unique properties at elevated temperatures. Herein, high-purity Cr2AlC powders had been synthesized by using a facile method with a mixture of Cr7C3, Cr3C2 and Al powders at 1200 °C for 3 h. Subsequently, the oxidation behaviors of Cr2AlC powders were investigated in dry air and pure steam at temperatures ranging from 900 to 1100 °C, respectively. In addition, the oxidation products were characterized and the mass gain curves were analyzed via the real physical picture (RPP) kinetic model. As a result, thicker Al2O3-rich oxide scale and porous Cr7C3 subscale were generated during dry air oxidation compared to pure steam oxidation. Notably, the oxidative active energy of Cr2AlC was 446.5 kJ/mol in pure steam, while in dry air it was decreased by 14.4%. Theoretical calculations further verified that Cr2AlC oxidizes more sluggishly in steam than in dry air.