Title

Degradation of Thermal Barrier Coatings by Fuel Impurities and CMAS: Thermochemical Interactions and Mitigation Approaches

Authors

Authors

P. Mohan; T. Patterson; B. Yao;Y. Sohn

Comments

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Abbreviated Journal Title

J. Therm. Spray Technol.

Keywords

air plasma spray; barrier overlay coatings; CMAS sand; environmental; degradation; thermal barrier coatings; vanadium pentoxide; ELECTROPHORETIC DEPOSITION; VANADIUM; TEMPERATURE; DURABILITY; CORROSION; Materials Science, Coatings & Films

Abstract

Degradation of free-standing yttria-stabilized zirconia (YSZ) and CoNiCrAlY coatings (300 mu m) due to V(2)O(5) and a laboratory-synthesized CMAS was investigated at temperatures up to 1400 A degrees C. Reactions, phase transformations, and microstructural development in coatings were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The molten deposits destabilized the YSZ and reacted with the thermally grown oxide with various phase transformations and reaction product formation. A dense, continuous environmental barrier overlay, based on oxides, applied by electrophoretic deposition was effective in mitigating the molten deposit attack. Enriching CMAS composition with Al promoted the crystallization of anorthite platelets and MgAl(2)O(4) spinel, and mitigated CMAS ingression. EPD MgO overlay was also effective in protection against V(2)O(5) melt by formation of magnesium vanadates. EPD alumina overlay deposited on thermal barrier coatings with APS 8YSZ and bond-coated IN939 superalloy retained its adhesion and structural integrity after prolonged furnace thermal cycle test at 1100 A degrees C.

Journal Title

Journal of Thermal Spray Technology

Volume

19

Issue/Number

1-2

Publication Date

1-1-2010

Document Type

Article; Proceedings Paper

Language

English

First Page

156

Last Page

167

WOS Identifier

WOS:000273671500018

ISSN

1059-9630

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