Thermal cycling behavior and failure mechanism of La2(Zr0.7Ce0.3)2O7/Eu3+-doped 8YSZ thermal barrier coating prepared by atmospheric plasma spraying

• DCL coating of LZ7C3/8YSZ prepared by APS shows promising performance at 1250 ± 50 °C.
• A Eu3+-doped luminescence sublayer was used to indicate the spallation situation and damage degree.
• Thermal cycling behavior and failure mechanism of DCL coating system were studied.

Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La2(Zr0.7Ce0.3)2O7 (LZ7C3) and Eu3+-doped zirconia which was partially stabilized by 8 wt% yttria (8YSZ:Eu) was prepared by atmospheric plasma spraying. Thermal cycling behaviors of DCL coating were studied. The DCL coating shows a promising performance at 1250 ± 50 °C. The DCL coating spalled bit by bit from the top ceramic layer (LZ7C3) to the inner ceramic layer (8YSZ:Eu) during thermal cycling. The similar thermal expansions of LZ7C3 and 8YSZ prolonged the thermal cycling life of the coating. The sintering effect and phase transformation of LZ7C3, formation of the thermally grown oxide (TGO), and the sintering of 8YSZ:Eu, are the primary factors for the spallation of DCL coating.