Modeling the cracking process of the YSZ thermal barrier coating under the thermal shocking loads

For low thermal conductivity and high corrosion resistance, yttria stabilized zirconia (YSZ), as a top coat (TC), is widely used in thermal barrier coatings (TBCs). However, the micro-structure of the TC is complicated and it has significant effects on it thermal shock resistance. Combining digital image processing technique with finite element mesh generation methods, finite element (EF) models based on actual microstructures of plasma sprayed YSZ thermal barrier coatings are built in this paper, so as to simulate the coating's dynamic failure process when suffering thermal shocking loads. The cracking process is revealed by calculating both the stress and strain evolutions within the coating. Based on the proposed method, the effects of porosity and distribution are further studied. The simulation results agree well with the experimental observation, indicating that the cracks are mainly caused by pore connectivity, which promotes the growth of cracks. This work is expected to be helpful to establish the quantitative relationship between the TBCs porosity and the coating's service performance.