The Effect of Top Coat Sintering on Ceramic Spallation in Plasma- Sprayed Thermal Barrier Coatings
J.A. Thompson, W. Ji, T.W. Clyne
Department of Materials Science & Metallurgy University of Cambridge
Abstract
The effect of exposure to high temperature on the Young's modulus of free standing air plasma-sprayed partially stabilised zirconia (APS-PSZ) top coat samples has been investigated. This effect has been found to be significant. Healing of small defects in the coating microstructure leads to an increase in the coating modulus and results in higher stresses in the system upon cooling to room temperature. The interfacial strain energy release rate, the driving force for debonding, has been calculated using a modified version of an existing numerical model. It is concluded that sintering of the top coat during heat treatments of the type typically encountered under service conditions can significantly enhance the likelihood of debonding.
keywords:driving force; numerical model; debonding; TBCs; Top Coat; Thermal Barrier; bond coat; splats; release rate
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