A new spallation mechanism of thermal barrier coatings on aero-engine turbine blades

Laboratory experiments were conducted to study the spallation behaviour of thermal barrier coatings (TBCs) on aero-engine turbine blades manufactured by the electron-beam physical vapour deposition technique (EB-PVD). Intact blades were heated at temperature 1135°C in a furnace for certain time and then cooled to the room temperature in the laboratory condition. It was found that no spallation occurred during cooling, but spallation happened at constant room temperature after cooling. The spallation mechanism is studied by using the mechanical model developed by Wang, Harvey et al. (2017a, 2017b), which are based on the hypothesis of pockets of energy concentration (PECs). Some observations of the spallation behaviour are well predicted by the model.