Study on cyclic thermal corrosion behavior of APS-7YSZ thermal barrier coating at room- and high temperature

The Thermal Barrier Coatings (TBCs) of aero-engine in the marine environment will be subjected to periodic salt solution corrosion and high-temperature corrosion. The cyclic corrosion tests were designed to study the change of corrosion resistance and degradation mechanism of YSZ coating on the thermal cycling and salt corrosion. The corrosion morphology, element distribution and phase composition were characterized by SEM, EDS and XRD. It is found that sulfate and Cl- reacted with the bond coat resulting in the volume expansion of the coating. Serious oxidation of Thermally Grown Oxide (TGO) layer, serious corrosion collapse area at the bond coat and the grain boundary corrosion at substrate were observed, indicating that molten salt penetrated the whole TBCs through the capillary action of cracks. Compared with other parts of the TBCs, the bond coat is more likely to be damaged by corrosion, which is the short board of the TBCs.