The Influence of Ceramic Topcoat Sintering on Stress Distribution in Plasma-sprayed Thermal Barrier Coatings

Abstract

The finite element model (FEM) was developed to evaluate the stresses induced by the ceramic topcoat sintering. The model contained four layers: substrate, bond coat, thermally grown oxide (TGO) and ceramic topcoat. The geometry of interface between bond coat and ceramic topcoat was simulated by a sinusoid. The sintering degree was introduced into the model via the elastic modulus change of ceramic topcoat. The results show that the sintering of ceramic topcoat has little contribution to the distribution of stress (both out-plane stress and in-plane stress), while the levels of these two stresses all increase dramatically with sintering of ceramic topcoat. Thus, the effect of sintering of ceramic topcoat in this case on the cracking model in TBCs can be neglected. On the contrary, the durability of the TBCs indeed decreases as ceramic topcoat sinters.