Structure-dependent residual stress of thermal barrier coating on turbine blade with exposure to high temperature

This work aims to investigate the structure-dependent residual stress of thermal barrier coating systems (TBCs) on actual turbine blades with curved surfaces, and explore the relationship between stress and failure in different blade regions. A specialized non-destructive stress measurement setup was developed for this purpose. The residual stresses in the top coat (TC) and thermally grown oxide (TGO) layer at different blade regions, namely the convex surface, the concave surface, and the leading-edge surface, were measured during isothermal oxidation services. A phenomenon of residual stress reversal was discovered. The structure-dependent failures of TBCs in different blade regions were found to be strongly correlated with the residual stress in the TGO layer, rather than the TC layer. These results significantly enhance our understanding of the failure mechanism and contribute to the prediction of service lifetimes for turbine blades equipped with TBCs.