Study of Nanostructured Thermal Barrier Coating ZrO2 and Evaluation of Thermal Stability and Hot Corrosion Behavior

The aim of this work, the behavior of hot corrosion and thermal stability of nanostructured thermal barrier coating made by yttria stabilized zirconia (8YSZ) was studied. For this purpose, on the stainless steel substrates double layer of NiCrAlY with thickness of 150 μm and nanostructured YSZ with thickness of 300 μm was deposited using atmospheric plasma spraying process. The high temperature cyclic oxidation test at 1000oC and 10-hour periods was performed in order to check the coating resistance against oxidation and thermal cycles. Type I hot corrosion test was carried out at 950oC for 4-hour combining with salts such as V2O5 and Na2SO4. The results show that the nanostructured coating with grain sizes less than 100nm in order to high oxygen ion permeability did not have a significant effect on reducing the TGO layer growth. However, the results of the hot corrosion test were showing that the formation of YVO4 crystals on the surface of the nanostructured YSZ coating. Due to the high diffusionability of nanostructured coating from the top surface to the depth of YSZ some vanadium diffused to the lower layer of YSZ nanostructured coating.