Microstructural, thermal characterization and CMAS corrosion resistance of novel quaternary (Y_0,25Er_0,25Tm_0,25Yb_0,25)₂Si₂O₇ high entropy disilicate material

A novel (Y_0,25Er_0,25Tm_0,25Yb_0,25)₂Si₂O₇ high entropy disilicate quaternary composition was synthesized from commercial oxide powders using ball milling and sintering processes as a candidate material for environmental barrier coatings (EBC). As-synthesized high entropy disilicate powders were sintered at different durations (12, 18, and 24 h) at 1600 °C in a muffle furnace before characterization. The XRD and SEM analyses revealed the single-phase monoclinic structure (β-type) with homogeneous elemental distribution for the sintered samples. The (Y_0,25Er_0,25Tm_0,25Yb_0,25)₂Si₂O₇ samples exhibited low thermal diffusivity coefficient, low thermal conductivity, a close coefficient of thermal expansion (CTE) to SiC and a high temperature stability. The (Y_0,25Er_0,25Tm_0,25Yb_0,25)₂Si₂O₇ samples were subjected to CMAS corrosion tests at 1300 °C with different durations (2, 12, and 24 h) to evaluate CMAS corrosion resistance. Additionally, Yb₂Si₂O₇ samples were prepared and subjected to molten CMAS in the same way for comparison. Based on the results, the CMAS corrosion resistance was improved with (Y_0,25Er_0,25Tm_0,25Yb_0,25)₂Si₂O₇ composition.