Stability of MnCr2O4 spinel and Cr2O3 in high temperature carbonaceous environments with varied oxygen partial pressures

Abstract

Abstract In this investigation, Cr 2 O 3 and MnCr 2 O 4 were comparatively tested at 1050 °C in carbonaceous environment with varied oxygen partial pressures. MnCr 2 O 4 exhibits much better resistance to carbonaceous attack than Cr 2 O 3 . The carburization rate of MnCr 2 O 4 decreases sharply with increasing oxygen partial pressures. The oxygen partial pressures have less effect on the carburization resistance of Cr 2 O 3 . The increased resistance of MnCr 2 O 4 to carburization is attributed to the dissolution of MnO into Mn–Cr–O spinel lattices with elevated oxygen partial pressures, which retards the decomposition and carburization of Mn–Cr–O spinel. The thermodynamic equations defining the carburization stability of MnCr 2 O 4 and Cr 2 O 3 are modified.