Evolution of high temperature corrosion behavior of La2(Zr0.7Ce0.3)2O7 with the addition of Y2O3 thermal barrier coatings in contacts with vanadate–sulfate salts

Thermal barrier coatings (TBCs) of La2(Zr0.7Ce0.3)2O7 with the addition of 3 wt.% Y2O3 (3Y-LZ7C3) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structure, surface and cross-sectional morphologies, hot corrosion behavior of the 3Y-LZ7C3 coatings were studied in detail. The present study investigates the hot corrosion performance of 3Y-LZ7C3 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 3Y-LZ7C3 produces LaVO4, YVO4, m-ZrO2 and CeO2, leaching La2O3 and Y2O3 from 3Y-LZ7C3 and causing the progressive destabilization transformation from t′ to m-ZrO2. The excess La2O3 in the as-deposited 3Y-LZ7C3 coating can largely aggravate the degradation of 3Y-LZ7C3 coating by both NaVO3 and Na2SO4 (Usually formation of the mixtures of LaVO3, (YkLa1−k)2O2SO4 and few of (YkLa1−k)2(SO4)3 (k = i or j) phases), resulting in very rapid disintegration of the coating. Phase transformation and chemical interaction are the primarily corrosive mechanisms for deterioration of 3Y-LZ7C3 coating.

► Phase transformation and chemical interaction are the primarily corrosive mechanisms for deterioration of 3Y-LZ7C3 coating. ► The 3Y-LZ7C3 material has a good corrosion resistance behavior and low hot corrosion ability. ► V element is obvious appeared in the outer region of 3Y-LZ7C3 coating.