A study of high temperature sulphidation products of pure and Sn-doped Fe-Cr alloys

Sulphidation products, i.e. scales and metallic cores resulting from high-temperature sulphidation carried out in an atmosphere of H-2/H2S mixture on pure and Sn-doped quasi-equiatomic Fe-Cr alloys in alpha and sigma phases were investigated with scanning electron microscopy, X-ray diffraction and Mossbauer spectroscopy. The scales were found to have a two-layer structure; the outer and the inner scale, Iron was found to exist in various forms within the scales magnetic and non-magnetic (Fe,Cr)(1-x)S (the latter obviously due to fine-grains), alpha-Fe (mostly within the inner scales) and (Fe,Cr)S,, (only in case of Sn-doped (T-phase alloys). Metallic cores were found to have Fe- and Sn-enriched outer mantel whose thickness was determined to be similar to45 mum and grain-like inner core with Cr-enrichment in form of CrS within the grain-borders. (C) 2002 Elsevier Science BY All rights reserved.