A parametric study of the stress state of thermal barrier coatings: Part I: creep relaxation Original Research Article

The mechanical loading of the thermal barrier coating (TBC)/thermally grown oxide (TGO)/bond coat interface region is calculated for a TBC coated superalloy specimen using a finite element model. The stress state depends crucially on the ratio of the loading rate caused by growth and swelling of the oxide layer and the unloading rate by creep relaxation. By performing parametric studies with large variations of the creep strengths of the TGO and the TBC, it is shown that a single parameter, which can be motivated by a simple model, can be used to estimate the resulting stresses in the high-temperature steady state. The influence of a change in geometry is also studied. The crucial parameter here is the aspect ratio of the (sinusoidal) interface, i.e., the ratio of the wavelength and the amplitude.