Silicon-modified boron nitride aerogels with enhanced thermal stability for thermal insulation applications in high-temperature

The boron nitride (BN) aerogel exhibits lightweight properties, excellent thermal stability, wideband wave transparency, and effective thermal insulation. However, most BN aerogels struggle to maintain stability at temperatures above 900 °C in air, and improving their oxidation resistance remains a challenge. This study presents a silicon-modified BN (Si-BN) aerogel with enhanced high-temperature stability, synthesized by mixing a silicon source with a BN precursor through the sol-gel method. Tetraethyl orthosilicate is used as the silicon source. The prepared Si-BN aerogel mainly contains BN and SiO₂ phases. Under heat exposure at 1300 °C, the temperature difference between the inside and exterior of the modified aerogel is 158.5 °C higher than that of the original aerogel, while maintaining a stable structure. After modification, the sample exhibited no significant deformation under a load more than 300 times its own weight. The compressive force-displacement results show that the maximum compressive stress increased by 15.9 times and the load-bearing capacity improved by 14.5 times. Combining these findings, it is clear that the modified composite aerogel exhibits both superior thermal insulation properties and mechanical load performance. Overall, these results demonstrate that the Si-BN aerogel exhibits excellent performance, providing valuable insights for the development and fabrication of advanced BN nanostructures and composite aerogel materials to meet future environmental demands.