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) C9-511-C9-519
DOI: 10.1051/jp4:1993954

Oxidation behaviour of simple and Pt-modified aluminide coatings on IN738 at 1100 °C

Y. Niu^{1, 2}, W. T. Wu¹, D. H. Boone³, J. S. Smith⁴, J.Q. Zhang¹ and C. L. Zhen<sup>1

1</sup>  Corrosion Science Lab., Institute of Corrosion and Protection of Metals, Academia Sinica, Shenyang 110015, China
²  Instituto di Chimica, Facoltà di Ingegneria, Universita di Genova, Fiera del Mare, Pad. D, 16129 Genova, Italy
³  Boone and Associates, 2412 Cascade Drive, Walnut Creek, California 94598, U.S.A.
⁴  Howmet Corporation, Thermatech Coatings Division, 555 Benston Road, Whitehall, Michigan 49461, U.S.A.

Abstract
The oxidation of both low and high-activity simple and Pt-modified aluminide coatings on nickel base superalloy IN738 has been studied in static air at 1100 °C up to 1000 h. For all coatings oxidation followed a parabolic law up to 400 h. The two Pt-modified coatings showed better protectiveness with lower mass gains and smaller rate constants, especially for long reaction times. The presence of Pt significantly improved the resistance to γ'-Ni₃Al formation, promoted selective oxidation of aluminium by preventing the transport of other elements outwards to Al₂O₃ scale and resulted in the formation of purer, slower-growing and more adherent A1₂O₃ scales, delaying the onset of scale spalling for two types of coatings and of oxide nodules growth for the high aluminium activity coating.

© EDP Sciences 1993