Influence of the deposition energy on the composition and thermal cycling behavior of La_2(Zr_(0.7)Ce_(0.3))_2O_7 coatings

摘要

Lanthanum-zirconium-cerium composite oxide (La_2(Zr_(0.7)Ce_(0.3))_2O_7, LZ7C3) coatings were prepared under different conditions by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphologies, cyclic oxidation behavior of these coatings were studied. Elemental analysis indicates that the coating composition has partially deviated from the stoichiometry of the ingot, and the existence of excess La_2O_3 is also observed. The optimized composition of LZ7C3 coatings could be effectively achieved by the addition of excess CeO_2 into the ingot or by properly controlling the deposition energy. Meanwhile, when the deposition energy is 1.15 X 10~4 - 1.30 X 10~4 J/cm~2, the coating has a similar X-ray diffraction (XRD) pattern to the ingot, and the thermal cycling life of the coating is also superior to other coatings. The spallation of the coatings occurs either within the ceramic layer approximately 6-10.5 mu m above its thermally grown oxide (TGO) layer or at the interface between ceramic layer and bond coat.