Lightweight and Super-Hydrophobic SiBCN-Reinforced BN Nanoribbon Aerogel for High-Temperature Thermal Insulation

Boron nitride (BN) aerogels are highly attractive for thermal insulation systems by virtue of their ultra-low density and exceptional thermal insulation performance; yet, their practical application is severely limited by inadequate load-bearing capacity and insufficient ablation resistance. In this study, a large-scale polymer-derived silicon boron carbonitride (SiBCN)-reinforced BN hybrid aerogel (SiBCN/BN) was fabricated via impregnation, solvothermal treatment, and pyrolysis; critically, the SiBCN aerogels construct a mesoporous network within the macropores of the BN nanoribbon skeleton. The density (0.073-0.236 g·cm-3) and the micromorphology of the SiBCN/BN hybrid aerogels can be tuned by adjusting the SiBCN loading. The hierarchical pore structure endows the SiBCN/BN aerogel with low thermal conductivity at room temperature (0.042 W·m-1·K-1) and at high temperature (0.061 W m-1 K-1 @ 800 °C and 0.080 W m-1 K-1 @ 1000 °C). Notably, the SiBCN/BN hybrid aerogel exhibits enhanced compressive strength (1.36 MPa, 405-fold higher than that of the BN aerogel) and improved ablation resistance (only 1% linear shrinkage after 1000 °C ablation). These superior properties are attributable to the reinforcement and protective effects imparted by the SiBCN phase. Furthermore, the SiBCN/BN hybrid aerogel shows super-hydrophobicity with a water contact angle up to 150.6°, endowing it with self-cleaning and moisture-resistant properties. The synergistic enhancement in mechanical strength and thermal stability makes the SiBCN/BN hybrid aerogel an exceptional choice for lightweight thermal insulation, expanding its practical utility and paving the way for next-generation multifunctional, robust, and durable aerogel systems.