Phase stability and CMAS corrosion resistance of RETaO4 (RE=Gd and Yb) at 1250 °C

Due to the restriction of CMAS corrosion, the YSZ TBCs are facing great challenges, which accelerates the development of the novel potential thermal barrier materials. This work has investigated the CMAS corrosion resistance of the novel thermal barrier material GdTaO 4 and YbTaO 4 to assess their potential in replacing the traditional YSZ . The results indicate that GdTaO 4 and YbTaO 4 possess excellent phase stability, and there is no phase transition after 150 h sintering at 1350 °C. The crystallization phenomenon has occurred in the residual CMAS when the reaction time is 0.5 h, and the main crystallization product is CaMgSi 2 O 6 . In comparison, when the reaction time increase to 10 h, the crystallization phenomenon has disappeared completely. The maximum reaction layer thickness of GdTaO 4 and YbTaO 4 are ∼10 μm and ∼6 μm after 10 h CMAS corrosion, respectively. The XRD patterns indicate that the main product after 10 h reaction is Ca 2 Ta 2 O 7 . Compared with the CaMgSi 2 O 6 , the Ca 2 Ta 2 O 7 possesses lower formation enthalpy and cohesion energy. With the reaction time rising, the formation of Ca 2 Ta 2 O 7 consumes lots of Ca elements and restrain the formation of CaMgSi 2 O 6 . Besides, the difference of GdTaO 4 and YbTaO 4 in CAMS corrosion resistance is also attributed to cohesion energy. These results indicate that GdTaO 4 and YbTaO 4 exhibit enormous potential to manufacture the novel TBCs in CMAS corrosion resistance compared with the YSZ.