Oxidation of Iron–Manganese–Sulphur Alloys. Part II: Sulphur Diffusion through Wüstite during Oxidation of Sulphur-Containing Iron

A mathematical study has been made to find the critical temperature, sulphur content, and oxidation rate for the suppression of liquid oxysulphide formation during oxidation of iron–sulphur alloy. The critical sulphur content for the formation of the liquid phase at the iron/wüstite interface decreases with increasing rate of oxidation. At low oxidation rates there is sulphur depletion near the surface of iron because of the diffusion of sulphur to the gas phase through the slowly growing wüstite layer. The results of this mathematical analysis were found to be in accord with previous experimental observations.