Abstract
The molten calcium-magnesium alumino-silicate (CMAS) deposits degradation of thermal barrier coatings (TBCs) is increasingly severe in advanced turbine engines. In this study, the thermochemical interaction of a promising TBC candidate material, (Yb0.7Gd0.3)4Hf3O12, with CMAS melts at 1300 ℃ and 1500 ℃ was systematically investigated. The apatite and reprecipitated fluorite with high melting points were crystallized rapidly when the ceramic reacted with CMAS melts, resulting in the formation of a dense crystalline layer to suppress further infiltration of CMAS melts. Moreover, as the reaction proceeded, the formation of garnet and cuspidine occurred at 1300 ℃ and 1500 ℃, respectively. The CMAS resistance of (Yb0.7Gd0.3)4Hf3O12 was significantly higher compared to that of Yb4Hf3O12, which could be attributed to the greater volume fraction of apatite and reprecipitated fluorite in the reaction products. The (Yb0.7Gd0.3)4Hf3O12 exhibited high effectiveness in mitigating CMAS infiltration, making it a potential candidate material for thermal barrier coatings.
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