Investigation of Hot Corrosion Resistance of usual CSZ and Layer Composite of CSZ/Nano-Al2O3 Plasma Sprayed Thermal Barrier Coatings

In this study, hot corrosion behavior of two-types of plasma sprayed thermal barrier coatings (TBCs), was evaluated: a) usual CSZ (ceria-stabilized zirconia) and b) layer composite coating (CSZ/Nano-Al2O3). Hot corrosion test was carried out on the surface of coatings in sulfate and vanadate molten salts at 1050 °C for 40 h. Microstructures and various phases were examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. As the results usual CSZ degraded, the formation of monoclinic ZrO2, rod type crystals of CeVO4, YVO4and semi-cubic crystals of CeO2 as hot corrosion products caused the degradation of mentioned TBC. Dense nano-alumina coating as an outer layer in layer composite coating reduced the infiltration of molten salts into TBC structure and resulted in the further resistance against hot corrosion.