Abstract
Double layer ceramic (DCL) thermal barrier coatings (TBCs) have attracted extensive attention due to their high thermal stability under high temperature. The thermal shock life and failure behaviors of DCL TBCs still remain a challenge. This work focuses on crystal structure, thermal expansion coefficients, thermal conductivity, microstructure and failure behaviors of the La2Zr2O7/YSZ (LZ/YSZ), La2Ce2O7/YSZ (LC/YSZ) and Gd2Zr2O7/YSZ (GZ/YSZ) DCL TBCs. The advanced ceramic material exhibits low thermal diffusivity and thermal conductivity. Furthermore, the advanced DCL TBCs exhibit good thermal shock life at 1100 °C due to the feathery microstructure with inter-columnar gaps and inter-columnar pores. After thermal shock test, the broken regions occur on the cracks area within ceramic coatings, TGO and interface leading to the TBCs instabilities. The TBCs interface instabilities play a key role on the failure behaviors of DCL TBCs.
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