J. Phys. IV France
Volume 118, November 2004
Page(s) 307 - 313

J. Phys. IV France 118 (2004) 307-313

DOI: 10.1051/jp4:2004118036

In situ X-ray diffraction contribution to the study of reactive element oxide coating effect on the high temperature oxidation behaviour of FeCrAl alloys

R. Cueff, H. Buscail, E. Caudron, F. Riffard, C. Issartel, S. Perrier and S. El Messki

Laboratoire Vellave sur l'Élaboration et l'Étude des Matériaux, Université de Clermont-Ferrand II, I.U.T. Département Chimie, 8 rue J.B. Fabre, BP. 219, 43006 Le Puy-en-Velay Cedex, France

The influence of yttrium oxide coating (processed by sol-gel method) on the oxidation behaviour of a commercial FeCrAl alloy (Kanthal A1) has been investigated during isothermal exposures in air at 1373K. The scale growth kinetic of the uncoated alloy obeys a parabolic rate law during the whole oxidation test whereas the kinetic curve of the Y-coated specimen exhibits an initial transient stage during the first hours, followed by a parabolic regime. The yttrium sol-gel coating deposited on the bare alloy does not conduct to the beneficial effect usually ascribed to the reactive elements. No oxidation rate improvement of the coated alloy is observed, the parabolic rate constants values are strictly identical for the both specimens. In situ X-ray diffraction reveals a marked influence of the reactive element on the composition of the oxide scale. The oxide layer formed on the yttrium-coated specimen revealed, in addition to $\alpha$-alumina which is the main oxide also identified on the bare specimen, the presence of yttrium aluminates (YAlO3, Y3Al5O12) located in the outermost part of the layer.

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