Diffusion and stress simulation analyses were conducted for the oxide layer causing TBC spallation, often observed in gas turbine hot gas path components. Diffusion analysis was based on two processes, that is, the formation of Al_2O_3 layer with internal Al, and formation of composite oxide layer inside of Al_2O_3 layer through diffusion of oxygen. Using the simulated oxide layer shape, elastic analyses were conducted to estimate thermal stress under cyclic thermal conditions and internal stress due to oxide layer expansion. These simulation results showed reasonable shapes and stress distribution of oxide layer and coating system proving that those methodologies were useful for predicting the spalling event for TBC systems.
