The design of sulphidation resistant materials: State-of-the-art and future prospects

The philosophy of conferring sulphidation resistance to alloys through the development of barrier layers of protective sulphides by selective sulphidation of appropriate elements is reviewed; The potential of the refractory and semi-refractory metals in promoting the development of barrier layers is illustrated. The efficacy of incorporating these elements in alloys to resist sulphidation in reducing atmospheres is described. The sulphidation behaviour of some model alloy systems developed using the theoretical framework described above is discussed. Consideration is given to the high temperature (HT) environmental compatibility of Ti-Al-based intermetallics in sulphur-containing environments.