Investigation of CMAS corrosion resistance for ZrO2-YTaO4 thermal barrier material at 1250 °C

The phase transformation instability and corrosion failure are the two main forms of degradation for thermal barrier coating (TBC) in the high temperature and CaO-MgO-Al₂O₃-SiO₂ (CMAS) environments. The addition of tantalum materials can effectively improve the phase stability of yttria-stabilized zirconia (YSZ) TBC. However, the effect of tantalum materials on the corrosion resistance performance and the mechanism of the coating against CMAS need to be analyzed in detail. A series of researches were conducted on the CMAS corrosion behavior of the novel ZrO₂-YTaO₄ material and the mechanism by which it resists CMAS. In order to obtain a composition with excellent comprehensive performance and CMAS resistance for TBC, the mechanical properties of the samples are discussed. The results demonstrated that, compared with YSZ, the ZrO₂-YTaO₄ material exhibited superior phase stability, mechanical properties and CMAS resistance property. When the Ta concentration in the ceramic matrix increases, it can lead to a reduction in the reaction between Y and CMAS, which can inhibit the spheroidisation of the TBC. Besides, a dense Ca₂Ta₂O₇ layer forms at the corrosion interface, the infiltration channels of CMAS in the ceramic are blocked, and the inter-diffusion between the ceramic and molten CMAS is inhibited, which effectively improves the corrosion resistance. On the other hand, the reduction in the Ca content in the molten CMAS resulting from the formation of the Ca₂Ta₂O₇ layer leads to an increase in the viscosity of the CMAS and prevents further infiltration into the matrix.