JSME International Journal Series A Solid Mechanics and Material Engineering
Online ISSN : 1347-5363
Print ISSN : 1344-7912
ISSN-L : 1344-7912
Material Evaluation
Mechanistic Understanding for Degraded Thermal Barrier Coatings
Kazuhiro OGAWATetsuo SHOJIHisahiko AOKINorio FUJITATaiji TORIGOE
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2001 Volume 44 Issue 4 Pages 507-513

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Abstract

A two-layer plasma sprayed thermal barrier coating on Ni base superalloy substrate was characterized. The coating was comprised of an inner layer of MCrAlY bond coating and an outer layer of 8 wt% yttria stabilized zirconia (YSZ) thermal barrier coating (TBC). After aging, the thermally grown oxide (TGO) layer at interface between YSZ and MCrAlY was observed. The TGO layer had two different contrast layers in the SEM images. The black one was closer to MCrAlY and the gray one was closer to YSZ. The thickness of both layers increased with aging. Countless porosities at the gray layer and microcrack at YSZ were also observed. Most of the macrocrack grew through the porosities. From this point of view one may say that the mechanism of macrocrack formation is a deterioration of adhesion accompanied by an increase of number of the porosities or the microcrack.

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© 2001 by The Japan Society of Mechanical Engineers
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