ABSTRACT The TBC system is examined with regards to its response to thermal exposure at high temperature. It has been established before that the thermally grown oxide (TGO) layer that forms upon bond coat oxidation is the key factor determining the performance of the TBC system and/or its failure. However, characteristics of TGO growth, bond coat rumpling, principles governing failure of TBC systems and the various failure mechanisms have been studied extensively in case of just super alloy with bond coat or with thick top coating. In this study super alloy/bond coat system with single splats of YSZ instead of thick topcoat is analyzed in order to scrutinize the effect on the first layer of splats during thermal exposure. The splats with microcracks are the building blocks of the top coat.The most important aspect of this layer is the inherent inter-splat and intra-splat porosity which undergoes sintering during thermal exposure. The interactions between the YSZ splats and the evolving TGO is directly linked to the presence or absence of bond coat oxidation. Therefore the high temperature behavior of this system is analyzed with variations in heat treatment involving, temperature, duration and environment of thermal exposure.
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