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

    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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