The evolution of microstructure, electromagnetic, mechanical properties and thermal stability of CVD SiC ceramics induced by BN interface

The composition and microstructure of SiC ceramics not only be closely related to their substrates, but also directly affect their properties. Therefore, it is necessary to reveal the induced growth mechanism of chemical vapor deposition (CVD) SiC ceramics on different substrates. Herein, porous mullite substrates were used to prepare BN interphase via chemical vapor infiltration (CVI), and then annealed at different temperatures to obtain BN with different crystallization degrees, subsequently CVD SiC ceramics on them to prepare M/BN_n/SiC composites. The microstructure, mechanical properties, microwave absorbing characteristics and thermal stability of the M/BN_n/SiC composites were investigated. The results show that the introduction of BN interphases with different crystallization degrees can effectively enhance the microwave absorption properties, mechanical properties and thermal stability of the M/BN_n/SiC composites. Noting that after annealing at 1000℃ and 1200℃, the M/BN₁/SiC and M/BN₂/SiC composites exhibit excellent microwave absorption properties, mechanical properties, and thermal stability. The study provides insights into the growth mechanisms of CVD SiC ceramics on BN interphase and their potential applications in advanced material systems.