Failure Mechanism Analysis of Environmental Barrier Coatings for SiC/SiC Ceramic-Matrix Composites Under Thermal Shock Tests

Environmental barrier coatings (EBCs) are crucial for ensuring the reliability and durability of ceramic-matrix composites in aeroengine service environments. In this study, SiC/SiC composite fabricated by polymer impregnation and pyrolysis (PIP) and chemical vapor infiltration (CVI) processes were used as the substrate, and the EBCs on the SiC/SiC composite surface were synthesized by an atmospheric plasma spraying (APS) method. The thermal shock tests were conducted at 1200 ℃ and 1300 ℃ for the PIP and CVI-SiC/SiC with EBCs, respectively. The EBCs on the PIP-SiC/SiC surface peel off at 1200 ℃ after 1455 cycles, while the EBCs on the CVI-SiC/SiC surface remain intact with no failure or peeling after 2000 cycles at 1300 ℃, which is mainly due to the difference in thermal conductivity of the substrates.