La2(Zr0.7Ce0.3)2O7——新型高温热障涂层

采用电子束物理气相沉积技术(EB-PVD)制备了新型La2(Zr0.7Ce0.3)2O7 (LZ7C3)热障涂层.研究了涂层的组分、显微结构、表面和横截面形貌以及恒温氧化行为.结果表明:涂层中La2O3/ZrO2/CeO2的相对含量偏离了化学计量比,但X 射线衍射(XRD)相结构与靶材非常相似.通过CeO2 掺杂后,LZ7C3体材料的热膨胀系数比La2Zr2O7 (LZ)大;在1100℃恒温氧化890h的条件下,LZ7C3涂层的抗氧化增重性能明显优于传统的Y2O3部分稳定化的ZrO2(8YSZ)涂层.此外,热膨胀不匹配、黏结层氧化和陶瓷涂层内部微观裂纹的出现可能是导致LZ7C3涂层恒温氧化失效的主要原因.

La2(Zr0.7Ce0.3)2O7-a New Oxide Ceramic Material for Thermal Barrier Coatings

La2(Zr0.7Ce0.3)2O7 (LZ7C3) as a candidate material for thermal barrier coatings (TBCs) was coated by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphologies and isothermal oxidation behavior of the LZ7C3 coating were studied. The results indicate that the composition of LZ7C3 coating deviates from the ingot through energy dispersive spectroscopy (EDS) detection, however, the X-ray diffraction (XRD) pattern of the coating is similar with the ingot. By CeO2 adulteration, the linear thermal expansion coefficient (TEC) of LZ7C3 bulk is larger than that of La2Zr2O7 (LZ), and the isothermal oxidation performance of the LZ7C3 coating is superior to that of traditionally zirconia containing 8%(mass fraction) yttria (8YSZ) after isothermally oxidized at 1100℃ for 890h. The failure of the LZ7C3 coating is mainly a result of the TEC mismatch, the abnormal oxidation of bond coat and the occurrence of micro-cracks inside ceramic topcoat.