Microstructural Evolution of Slurry Fe Aluminide Coatings during High Temperature Steam Oxidation

Abstract:

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Slurry iron aluminide coatings are very resistant to steam oxidation at 600-650º C. These coatings can be used to protect new generation Ultra Super Critical (USC) steam power plant ferritic/martensitic steel components. The microstructure of the initially deposited coating changes as a function of time, mainly due to coating-substrate interdiffusion, going from mostly Fe2Al5 to FeAl, causing the precipitation of AlN in those substrates containing a minimum content of N and moreover, developing Kirkendall porosity at the coating-substrate interface. Steam oxidation at 650º C causes the formation of a protective thin layer of hexagonal χ-Al2O3 phase along with some α- and γ-Al2O3 after the first few hours of exposure. However, despite the relatively low temperature, and after several thousands hours the protective layer was mostly composed of α-Al2O3. A study of the evolution of the microstructure of slurry aluminide coatings deposited on P92 and exposed to steam at 650º C has been carried out by scanning and transmission electron microscopy and X ray diffraction.

Info:

Periodical:

Materials Science Forum (Volumes 595-598)

Edited by:

Pierre Steinmetz, Ian G. Wright, Alain Galerie, Daniel Monceau and Stéphane Mathieu

Pages:

251-259

DOI:

10.4028/www.scientific.net/MSF.595-598.251

Citation:

A. Agüero et al., "Microstructural Evolution of Slurry Fe Aluminide Coatings during High Temperature Steam Oxidation", Materials Science Forum, Vols. 595-598, pp. 251-259, 2008

Online since:

September 2008

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Price:

$35.00

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