Investigation of corrosion behavior of ZrO2-CeO2-Y2O3-Al2O3-SiC thermal barrier coating in Na2SO4-V2O5 environment at 950 °C

Hot corrosion in Na2SO4-V2O5 environment has been regarded as a major challenge in the destruction of thermal barrier coatings (TBCs). The present study introduces a CoNiCrAlY/CSZ+Al2O3+SiC TBC with enhanced resistance to hot corrosion compared to the CSZ. CoNiCrAlY/CSZ+Al2O3+SiC and CoNiCrAlY/CSZ were applied on CoNiCrAlY, as a bond coat to nickel-based superalloy (IN738LC) using the atmospheric plasma spray (APS) technique. Hot corrosion behavior of TBCs was investigated in a cyclic approach (2 hours for each cycle) using Na2SO4-55 wt.% V2O5 salts at 950°C. The findings showed the higher hot corrosion resistance of CoNiCrAlY/CSZ+Al2O3+SiC TBC compared to CoNiCrAlY/CSZ coating system. The transformation of tetragonal zirconia to monoclinic ZrO2 and formation of YVO4 and CeVO4 crystals as hot corrosion products led to the degradation of the mentioned TBCs.