Modelling the stress state of a thermal barrier coating system at high temperatures

Abstract A model is proposed to assess the time- and temperature-dependent creep and oxidation behavior of typical thermal barrier coating (TBC) systems consisting of EB-PVD manufactured partially stabilized ZrO2 and a plasma-sprayed MCrAlY bond coat (BC) on a typical Ni-base sheet alloy. The creep behavior of the BC was investigated by compression tests at the NiCoCrAlY alloy PWA 1370. With the objective of describing the formation of the so-called thermally grown oxide, an oxidation kinetic for the BC alloy is presented, which predicts the oxide thickness as a function of time and temperature. Using a finite element model of the complete TBC system, the influence of time- and temperature-dependent oxide growth and deformation behavior of the components on the stress development was studied. The obtained results show a development of compressive stresses above the peaks and of tensile stresses in the valleys of the rough TBC/BC interface. With this, the delamination stress between top coat and BC, which ...