The self-sacrificial protection mechanism of YTa3O9/8YSZ double-ceramic-layer thermal barrier coatings under high-temperature durability

Conventional 8YSZ thermal barrier coatings (TBCs) often experience crack initiation and premature spallation due to phase transformation-induced volume changes at high temperatures, limiting their application. In contrast, YTa 3 O 9 shows great potential as a next-generation TBC material due to its unique double-oriented domain structure, which offers low thermal conductivity and minimal volume changes during phase transformation. In this paper, YTa 3 O 9 single-layer and YTa 3 O 9 /8YSZ double-ceramic-layer (DCL) TBCs are prepared via atmospheric plasma spraying (APS). A comprehensive evaluation of their service life and failure behavior is performed through high-temperature oxidation, high-temperature thermal shock, and high-temperature CMAS corrosion thermal shock tests. The results show that YTa 3 O 9 /8YSZ DCL-TBCs exhibit the significantly enhanced high-temperature performance and serve life compared to the YTa 3 O 9 single-layer TBCs. The introduction of CMAS corrosion media accelerates coating failure, reducing the thermal cycle life of YTa 3 O 9 single-layer TBCs and YTa 3 O 9 /8YSZ DCL-TBCs by 62.76% and 53.33%, respectively, compared to thermal shock alone. YTa 3 O 9 coating in YTa 3 O 9 /8YSZ DCL-TBCs undergoes layer-by-layer spallation to release stresses in a self-sacrificing manner, thereby protecting the underlying structural components.