Thermal barrier coatings of new rare-earth composite oxide by EB-PVD

Thermal barrier coatings (TBCs) of La2(Zr0.7Ce0.3)2O7 (LZ7C3) with the addition of 3 wt.% Y2O3 (3Y-LZ7C3) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structures, surface and cross-sectional morphologies, thermal cycling behaviors of these coatings were studied in detail. The thermal cycling test at 1373 K in an air furnace indicates that the 3Y-LZ7C3 coating has a lifetime of 1134 cycles which is about 18% longer than that of LZ7C3 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 3Y-LZ7C3 coating. The failure of 3Y-LZ7C3 coating is probably a result of the reduction-oxidation of cerium oxide (Ce2O3 and CeO2), the solid solution reactions between La2O3 and Y2O3 (or ZrO2), the visible cracks initiation, propagation and extension, the abnormal oxidation of bond coat and the thermal expansion mismatch between ceramic coating and bond coat.