Two finite element (FE) models are discussed in this paper and compared to experimental results: (i) a micro-scale model describes the formation of initial delaminations and (ii) a segmentation crack model analyses the interaction between delaminations and segmentation cracks on the meso-scale.
It was found that initial delaminations develop mainly in the valley of asperities at the TGO/TBC interface, both in fast and slow creeping bond-coat materials. Segmentation cracks can be found in the coating system from the first thermal cycle. They promote the development of delaminations between two segmentation cracks. The propagation of delaminations is not stopped in the TBC and the delaminations grow together with the segmentation cracks. In conclusion, a possible scenario of TBC failure in the analysed model system is presented.