Hot corrosion behavior of La2Zr2O7 with the addition of Y2O3 thermal barrier coatings in contacts with vanadate-sulfate salts

Thermal barrier coatings (TBCs) of La2Zr2O7 with the addition of 3 wt.% Y2O3 (LZ3Y) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structure, surface morphology, hot corrosion behavior of the LZ3Y coating was studied in detail. The present study investigates the hot corrosion performance of LZ3Y coating in the presence of molten mixture of Na2SO4 + V2O5 at 1173 K for 100 h. X-ray diffraction (XRD) indicates that the chemical reaction between NaVO3 and LZ3Y produces LaVO4, YVO4 and m-ZrO2, leaching La2O3 and Y2O3 from LZ3Y and causing the progressive destabilization transformation from t to m-ZrO2. The excess La2O3 in the as-deposited LZ3Y coating can largely aggravate the degradation of LZ3Y coating by both NaVO3 and Na2SO4, resulting in very rapid disintegration of the coating. Phase transformation and chemical interaction are the primarily corrosive mechanisms for deterioration of LZ3Y coating. (C) 2010 Published by Elsevier B.V