Preparation and water vapor corrosion behavior of high entropy rare earth disilicate (Y_0.25Yb_0.25Ho_0.25Er_0.25) ₂Si₂O₇

In this work, a new type of high-entropy rare earth disilicate, denoted as (Y_0.25Yb_0.25Er_0.25Ho_0.25)₂Si₂O₇ or simply (4RE_0.25)₂Si₂O₇ ceramic was synthesized using the sol-gel method. Its excellent resistance to water vapor corrosion was demonstrated. The results revealed that the high-entropy (4RE_0.25)₂Si₂O₇ exhibited consistent physical and chemical properties from room temperature to 1400 °C, as indicated by TG-DSC analysis. Moreover, the coefficient of thermal expansion (CTE) of (4RE_0.25)₂Si₂O₇ measured 3.95 × 10⁻⁶ K^-1, which closely resembled that of SiC_f/SiC composites. Notably, the weight loss of the bulk (4RE_0.25)₂Si₂O₇ was a mere 0.056 %, showcasing its superior performance compared to Yb₂Si₂O₇ ceramics. As a result, the novel (4RE_0.25)₂Si₂O₇ ceramic holds promise for enhancing the water vapor corrosion resistance of SiC_f/SiC composites, whether employed as coatings or matrices.