Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température
J. Phys. IV France 03 (1993) C9-197-C9-204
DOI: 10.1051/jp4:1993918
High temperature corrosion of MA 956 in sulfidizing/oxidizing/carburizing environments : a study of the influence of preoxidation on the corrosion resistance of the alloy
F. Uberti1, F. Gesmundo2 and G.P. Toledo31 Lab. of High Temperature Corrosion, CISE SpA, V. Reggio Emilia 39, 20090 Segrate (MI), Italy
2 Istituto di Chimica, Università di Genova, Fiera del Mare, Pad. D, 16129 Genova, Italy
3 ENEL/DSR-CRTN, Via Monfalcone 15, 20132 Milano, Italy
Abstract
The influence of preoxidation and of the presence of HCl or of char deposits upon the high temperature corrosion of MA 956 in simulated coal-gasification environments has been studied at 700°C for periods up to 2000 h. The corrosion of the blank material produced mixed Al-Cr sulfide-oxide scales, while preoxidation led to the development of alumina scales well adherent to the substrate which were quite protective since no sulfide formation was observed even after 1000 h exposure to the sulfidizing gases. On the contrary, HCl produced a significant enhancement of the corrosion rate of the bare alloy : however, preoxidation was able to afford a reasonable degree of protection even in this case. Coal chars had little effect on the corrosion in the absence of HCl.
© EDP Sciences 1993