Cohesive zone modelling of thermal barrier coatings interfacial properties based on three-dimensional observations and mechanical testing

Abstract : This study aims to identify interfacial mechanical properties of a typical EB-PVD TBC system. High temperature influence on the evolution of the phase transformation in the bond-coat layer was quantitatively measured using synchrotron laminography 3D imaging of the thermal barrier coating (TBC) microstructure. Mechanical compressive tests have enabled strain at spallation to be characterised as a decreasing function of time spent at high temperature. A higher level of compression has also enabled the growth of interfacial crack after the first spallation event. On this basis the parameters of the Needleman's cohesive zone model were identified. The influence of the morphology of the ceramic/metal interface on damage evolution was numerically tested and was seen to be consistent with known delamination process in TBCs.