Thermal cycling behavior of La 2Zr 2O 7 coating with the addition of Y 2O 3 by EB-PVD

Abstract

Thermal barrier coatings (TBCs) of La 2Zr 2O 7 (LZ) with the addition of 3 wt.% Y 2O 3 (LZ3Y) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structures, surface and cross-sectional morphologies, cyclic oxidation behaviors of these coatings were studied in detail. The thermal cycling test at 1373 K in an air furnace indicates that the LZ3Y coating has a lifetime of 617 cycles which is about 10% longer than that of LZ coating. The improvement of chemical homogeneity of the coating, the superior growth behavior of columns and the favorable mechanical properties are all very helpful to the prolongation of thermal cycling life of LZ3Y coating. The failure of LZ and LZ3Y coatings is mainly a result of the excess La 2O 3, the chemical incompatibility of ceramic coatings with TGO layer, the thermal expansion mismatch between ceramic coatings and bond coat, and the outward diffusion of alloying elements into the ceramic coatings.