Thermal cycling lives of plasma sprayed YSZ based thermal barrier coatings in a burner rig corrosion test

This study aims to provide an insight into the effect of CaO-MgO-Al₂O₃-SiO₂ (CMAS) on the thermal cycling performance of plasma sprayed yttria partially stabilized zirconia (YSZ) coatings. The microstructural evolution and thermal cycling lives of YSZ coatings with and without CMAS corrosion were comparatively studied by a burner rig corrosion test. The experimental and simulation results showed that the molten CMAS that penetrated into the coatings reduced the porosity and increased the in-plane modulus and stiffness of coatings. During cooling, the large in-plane stress in the CMAS penetrated layer promoted the formation of through-thickness cracks, which significantly accelerated the oxidation of bond coat. Compared to the non-corroded coatings, the large out-of-plane stress that was normal to the YSZ/bond coat in the CMAS corroded coatings promoted the diffusion of Cr, Co and Ni ions, which significantly improved the growth of mixed oxides (such as Cr₂O₃, NiO and spinels) and thickened the TGO layer which eventually resulted in the spallation of TBCs.