Research Progress on Oxide-Based Bond Coats for Environmental Barrier Coatings

Environmental Barrier Coatings (EBCs) critically determine the performance of SiC ceramic matrix composites (CMCs) in high-temperature water-oxygen environments. As a key component of EBCs, the bond coat must ensure adhesion between the coating and substrate while effectively blocking the penetration of oxidizing/corrosive media to the SiC substrate. Current widely studied bond coat materials, such as Si and Si+HfO₂, are limited by the relatively low melting point of Si (~1410 ℃), restricting their upper service temperature. Oxide materials with higher melting points and inherent oxidation resistance have emerged as promising candidates for high-temperature bond coats. This article reviews the research progress on oxide-based bond coats, including mullite, SiO₂-HfO₂, HfO₂-Al₂O₃-SiO₂, cordierite and Yb₂Si₂O₇, focusing on their fabrication techniques, material properties and oxidation/corrosion resistance. Among these, mullite and SiO₂-HfO₂ systems demonstrate significant application potential under specific conditions. Building on these findings, this work further addresses challenges in oxide bond coats, such as brittleness, controllable synthesis, limited oxidation resistance and interfacial bonding strength. The analysis provides foundational insights and guidance for the design, development, and performance optimization of next-generation oxide-based bond coats for ultra-high-temperature environments (≥1400 ℃).