Microstructure and water corrosion behavior of (Lu_0.2Yb_0.2Er_0.2Tm_0.2Sc_0.2)₂Si₂O₇ high-entropy rare-earth disilicate coating for SiC coated C/C composites

In order to make carbon/carbon composites suitable for application in gas turbine engine, it is necessary to develop environmental barrier coatings (EBCs) to protect them from reacting with water vapor. In our previous work, a novel high-entropy rare-earth disilicate (Lu_0.2Yb_0.2Er_0.2Tm_0.2Sc_0.2)₂Si₂O₇ ((5RE_0.2)₂Si₂O₇) has been developed and verified as a promising candidate for EBCs. In this work, the (5RE_0.2)₂Si₂O₇ coating was synthesized on the surface of SiC coated C/C composites by supersonic atmospheric plasma spraying method. The protective performance and mechanism of this coating under high temperature water vapor environment was explored in detail. Results showed that the weight change of the sample coated with (5RE_0.2)₂Si₂O₇ was only 0.2% after corrosion for 100 h at 1500 ºC, which proved that (5RE_0.2)₂Si₂O₇ coating could significantly improve the resistance of C/C composites against water vapor corrosion. This work may provide theoretical basis for the design and application of high-entropy rare-earth silicates as EBCs.