EDP Sciences Journals List
Issue J. Phys. IV France
Volume 03, Number C9, Décembre 1993
Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of Materials
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température
Page(s) C9-599 - C9-606
DOI http://dx.doi.org/10.1051/jp4:1993963

Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of Materials
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température

J. Phys. IV France 03 (1993) C9-599-C9-606

DOI: 10.1051/jp4:1993963

High temperature attack by SO2 of laser boronized iron

H. Dao Duong, A. Galerie, M. Pons and M. Caillet

Laboratoire Science des Surfaces et Matériaux Carbonés, U.R.A. C.N.R.S. n° 413, E.N.S. d'Electrochimie et d'Electrométallurgie de Grenoble, Institut National Polytechnique de Grenoble, B.P. 75, Domaine Universitaire, 38402 Saint-Martin d'Hères, France


Abstract
Laser alloying of boron predeposited on iron samples led to Fe-Fe2B alloys, with composition and microstructure depending on the irradiation conditions. Three different surface alloys were prepared corresponding to hypo-, hyper- and eutectic microstructures. This last kind of surface alloy exhibited the best behaviour in static SO2 between 400 and 600 °C. The parabolic rate law, tending to a 3rd and 4th power law at the highest temperatures was explained as the result of outward iron diffusion leading to a magnetite external sublayer and inward SO2 and S2 transport, allowing the formation of a FeS-B2O3 internal sublayer. In this sublayer, slowly reacting Fe2B transforms to B2O3 leading to an increased blocking during the course of the reaction.



© EDP Sciences 1993