Thermal barrier coating of lanthanum–zirconium–cerium composite oxide made by electron beam-physical vapor deposition

Lanthanum–zirconium–cerium composite oxide (La2(Zr0.7Ce0.3)2O7, LZ7C3) as a candidate material for thermal barrier coatings (TBCs) was prepared by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, thermophysical properties, surface and cross-sectional morphologies and cyclic oxidation behavior of the LZ7C3 coating were studied. The results indicated that LZ7C3 has a high phase stability between 298 K and 1573 K, and its linear thermal expansion coefficient (TEC) is similar to that of zirconia containing 8 wt% yttria (8YSZ). The thermal conductivity of LZ7C3 is 0.87 W m−1 K−1 at 1273 K, which is almost 60% lower than that of 8YSZ. The deviation of coating composition from the ingot can be overcome by the addition of excess CeO2 and ZrO2 during ingot preparation or by adjusting the process parameters. The failure of the LZ7C3 coating is mainly a result of the occurrence of micro-cracks inside ceramic topcoat, which cause the abnormal oxidation of bond coat.