A novel efficient preparation route for BN matrix composites reinforced with Al ₂ O ₃ fibers based on textured design

Conventional BN-based composites often limited by high porosity and long processing cycles, which severely restrict their mechanical performance and engineering applications. To overcome these limitations, a novel organic–inorganic hybrid matrix combined with a hot-compression orientation strategy is proposed. Liquid-phase polyborazylene (PBZ) was employed to promote the rearrangement and alignment of h-BN lamellae during pressing, and subsequent pyrolysis yielded a dense and continuous BN matrix with in-situ precipitated nanocrystals serving as load-transfer nodes. This process significantly enhanced densification, reduced porosity, and enabled the construction of an ordered lamellar structure. Unlike conventional PIP processes that typically require ~10 repeated infiltration–pyrolysis cycles, this method achieves dense composites in a single pyrolysis step, effectively avoiding fiber damage and greatly shortening the fabrication cycle. The synergistic effects of aligned lamellae inducing extended crack propagation paths and in-situ nanocrystals providing additional load-transfer mechanisms effectively improved the mechanical performance of the composites. The proposed PBZ-assisted hybrid matrix and lamellar-orientation design strategy offers a new and efficient route for developing high-performance BN-based composites with excellent wave-transmitting and thermal protection capabilities.