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) C9-257 - C9-264
DOI http://dx.doi.org/10.1051/jp4:1993924

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) C9-257-C9-264

DOI: 10.1051/jp4:1993924

Beneficial effects of Y2O3 dispersion on Al2O3 protective coating

Y. Ikeda and M. Yata

National Research Institute for Metals, 1-2-1, Sengen, Tsukuba, 305, Japan


Abstract
We have studied the mechanism by which dispersed Y2O3 exerts beneficial effects on the oxidation protection of an Al2O3 coating (film) on the basis of the following models : 1) Y2O3 suppresses surface segregation of S by trapping it in the alloy matrix and accordingly suppresses spalling of the Al2O3 film ; 2.1) The diffusion of alloying elements into the Al2O3 film is retarded by dispersed oxide particles, probably through formation of a diffusion barrier at the Al2O3/alloy interface ; 2.2) The diffusion in film is retarded through incorporation of Y2O3 into the film ; 3) Y2O3 acts as an adhesive at the Al2O3/alloy interface ; 4) Y2O3 incorporated into the film suppresses the spalling by increasing the plasticity of the film. We reached the following conclusions : 1 is very important, 2 is also significant but 3 and 4 are negligible.



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