An investigation of the effects of isothermal exposure on microstructural evolution and oxidation in a thermal barrier coating

This paper presents the results of a systematic investigation of the effect s of isothermal exposure on the microstructural evolution and the isotherma l oxidation behavior of a thermal barrier coating with a platinum aluminide bond coat. Sintering of the columnar partially stabilized zirconia is show n to occur during isothermal exposure at 1100 degreesC for durations up to 200 hours. This is accompanied by roughening of the TGO layers, the formati on of hemi-spheroidal defects, parabolic coarsening of the TGO and final pu ll-out of the zirconia layers. The implications of the results are discusse d for the analysis and design of TBCs for aeroengine applications.