Corrosion performance of high-entropy (Ho0.2Er0.2Tm0.2Yb0.2Lu0.2) 2Si2O7 environmental barrier coating material under CMAS conditions at 1500 ℃

Improving the corrosion resistance of environmental barrier coatings (EBCs) to molten calcium-magnesium-aluminosilicate (CMAS) salt is an urgent requirement for aeroengine blades. In this work, a novel high-entropy (Ho 0.2 Er 0.2 Tm 0.2 Yb 0.2 Lu 0.2 ) 2 Si 2 O 7 ((5RE 0.2 ) 2 Si 2 O 7 ) environmental barrier coating material was developed, and molten CMAS corrosion resistance of (5RE 0.2 ) 2 Si 2 O 7 ) was systematically investigated at 1500 °C. The prepared (5RE 0.2 ) 2 Si 2 O 7 ceramic possesses a single and stable β-phase structure with high-temperature stability from room temperature to 1500 ℃. The thermal conductivity of (5RE 0.2 ) 2 Si 2 O 7 ranges from 1.46 to 3.49 W·m −1 ·K -1 at room temperature to 1500 ℃. A rapid reaction of (5RE 0.2 ) 2 Si 2 O 7 with molten CMAS produced Ca 2 RE 8 (SiO 4 ) 6 O 2 apatite at 1500 ℃. The reaction layer thickness was only 95.9±8.6 μm which effectively inhibited the infiltration and diffusion of molten CMAS salt. In contrast, Yb 2 Si 2 O 7 ceramic, when exposed to molten CMAS at 1500 ℃, showed no reaction. Instead, the molten CMAS salt penetrated into the interior of Yb 2 Si 2 O 7 along grain boundaries and voids, forming bubble cracking and ultimately, structural degradation. These results suggest that the high-entropy (5RE 0.2 ) 2 Si 2 O 7 ceramic material is a potential candidate for next-generation EBC with excellent resistance to CMAS corrosion.