Comparison of oxidation behaviors of Cr7C3 at 1173 K and 1273 K

Abstract

Cr7C3 has properties of high strength, low density, good chemical stability, and resistance against corrosion and oxidation at high temperature. With these excellent properties, Cr7C3 is considered especially suitable as a high temperature material. However, little attention has been paid to the oxidation behavior of Cr7C3. In this work, the oxidation behavior of Cr7C3 at 1173 K and 1273 K, with seven durations from 10 h to 70 h, was investigated. After testing, oxide morphology and phase composition were observed, and identified by SEM and XRD respectively. The results indicate that the anti-oxidation levels of Cr7C3 at the oxidation times of 1173 K and 1273 K both belong to the total anti-oxidation grade; the oxidation rate constant and oxidation rate of Cr7C3 at 1273 K show improvement over those at 1173 K by about one order of magnitude and more than two-fold respectively. The result also indicates that Cr2O3 does not peel off from the surface of Cr7C3 at 1173 K; however, at 1273 K it does peel off. Furthermore, the calculation result indicates that the critical compressive stress value for Cr2O3 peeling from the surface of Cr7C3 lies between 1.14 GPa and 1.27 GPa.