Mass loss of Cr₂O₃ during exposure to steam at 923 K and its suppression by sulfur doping

Mass loss occurs in Cr₂O₃ when it is exposed to steam at 923 K for 0.5 Ms or 1.3 Ms. The presence of S at an impurity level of 23 ppm in the oxide suppresses the mass loss by about a half. For example, for the 0.5 Ms exposure, the mass loss is about 0.055% in pure Cr₂O₃ but about 0.030% in S-doped Cr₂O₃. This result is related closely to our previous result that the existence of 50 ppm S in high Cr ferritic steels causes a tremendous improvement in the steam oxidation resistance at 923 K.