Preparation, Characterization, and Optimization of Interface Phase in Fiber-Reinforced Ceramic Matrix Composites

The performance of continuous fiber-reinforced ceramic matrix composites (CMCs) is highly dependent on the design of the interface phase between the fibers and the matrix. This paper provides a systematic review of the preparation methods, structural characteristics, performance regulation, and applications of three mainstream interface phases—pyrolytic carbon (PyC), boron nitride (BN), and silicon carbide (SiC)—in CMCs. Pyrolytic carbon (PyC) interface phases are primarily prepared using chemical vapor infiltration/deposition (CVI/CVD) methods, with their texture types (e.g., isotropic, medium texture, high texture) regulated by factors such as precursor type, gas composition, temperature, and pressure. PyC possesses a good layered structure and weak interfacial bonding characteristics, enabling effective crack deflection and fiber pull-out. However, its poor oxidation resistance (oxidation onset temperature of approximately 370 °C) limits its application in high-temperature oxidative environments. Boron nitride (BN) interface phases are also prepared using the CVD method, with the commonly used precursor being the BCl3–NH3–H2 system. BN possesses a graphite-like layered structure and excellent high-temperature oxidation resistance (oxidation onset temperature >800 °C), and its oxidation product B2O3 also exhibits self-healing capabilities. The crystallinity, texture type, and thickness of the BN interface phase significantly influence its interface bonding strength and the toughness of the composite material, typically requiring subsequent heat treatment to enhance its crystallinity and stability. Silicon carbide (SiC) interface phase has high modulus (~650 GPa), good thermal stability and oxidation resistance and can effectively enhance the toughness of composite materials through crack pinning, deflection, and passivation mechanisms. SiC interface phase can be prepared using CVD and other methods, and its structural properties are regulated by parameters such as deposition temperature, pressure, and precursor ratio. Multi-layer or gradient structures (e.g., SiC/BN, SiC/PyC) can further optimize their environmental barrier performance and thermal-mechanical adaptability. In summary, PyC, BN, and SiC interface phases each exhibit unique characteristics. They should be selected and structurally designed based on specific application environments (e.g., temperature, atmosphere, mechanical load) to optimize the performance of CMCs.