Thermal property and failure mechanism of LaDyZrO thermal barrier coatings by electron beam physical vapor deposition

Thermal barrier coatings (TBCs) have attracted much interest several decades ago. Lanthanum zirconate La2Zr2O7 is known for its high melting point and good thermal stability in aircraft engine environment. The thermal property and failure mechanism of the advanced TBCs still remain a challenge. This study focuses on phase, thermal expansion coefficient, microstructure, composition, thermal durability, and failure behaviors in the LaDyZrO/YSZ/NiCoCrAlYHf TBCs. The LaDyZrO and YSZ ceramic layers are deposited by EB-PVD, and NiCoCrAlYHf metallic layer is deposited by AIP-PVD. The as-deposited TBCs exhibit good thermal cycling life and thermal shock life at 1100 °C due to the improvement of TEC, the formation of dual phase structure and columnar structure. The locally broken region of the YSZ/TGO interface, LaDyZrO/YSZ interface and further the LaDyZrO layer would facilitate propagation of the interface instability. The element diffusion and cracks evolution might be two critical factors for the failure mechanism of LaDyZrO/YSZ/NiCoCrAlYHf TBCs. This study of thermal property and failure mechanism would be used to explain the element diffusion behavior and microstructure evolution of other advanced TBCs. [Display omitted] •The LaDyZrO exhibits complex dual-phase structure and high thermal expansion coefficient.•The LaDyZrO exhibits feathery microstructure leading to high thermal durability.•The element diffusion and cracks evolution are two critical factors for the failure mechanism.•The LaDyZrO/YSZ/NiCoCrAlYHf TBCs might be regarded as one advanced TBCs.