Effect of Different Thermal Cycles on TBC Spallation Lifetime

Abstract

Abstract The effect of different thermal cycle profiles on thermal barrier coating (TBC) spallation lifetime was investigated. Fick’s law was used to describe the thermally grown oxide (TGO) buildup. It was found that Fick’s law can be used to correlate between damage thickness and oxide thickness for different thermal cycle profiles. A critical oxide thickness of 12 μm can be associated with spallation life for the 8 wt% YSZ /PtAl/Rene N5 EB-PVD system. The importance of this correlation is that, for a given thermal cycle profile, the number of cycles to spallation can be predicted analytically using Fick’s law. The effect of maximum temperature, minimum temperature, holding time, and number of cycles were studied. It was found that by using the actual thermal cycle profile, accounting for cumulative oxide buildup throughout the complete cycle, the TBC spallation lifetime can be estimated reasonably well.