Silica (SiO₂) aerogels are widely used in high-temperature insulation materials due to their low thermal conductivity. The hydrophobicity of SiO₂ aerogels is considerably important for maintaining high-thermal insulation performance for a long duration. Traditional methods for the hydrophobic modification of SiO₂ aerogels involve the modification of organic functional groups present on aerogel surfaces to replace original hydrophilic hydroxyl functional groups. However, due to the thermal damage of functional groups, SiO₂ aerogels lose their hydrophobicity at high temperatures (400 °C), which limits the aerogel application in high-temperature fields. This study proposed a new hydrophobic method, chemical vapour deposition, to deposit a layer of hydrophobic boron nitride (BN) on the SiO₂ aerogel surface. The surface hydrophobic angle of the BN-modified SiO₂ aerogel reached 144.3°, and hydrophobic destruction temperature increased to 700 °C, indicating stable hydrophobicity. The method can be used to a decrease in aerogel surface energy through the deposition of a nano-BN film on the aerogel surface layer while maintaining the porous structure of the unmodified aerogel. The deposited BN layer protects the silica skeleton. This layer inhibits silica crystallisation and improves the thermal stability of aerogels.

二氧化硅（SiO ₂）气凝胶由于导热系数低而被广泛用于高温绝缘材料中。SiO ₂气凝胶的疏水性对于长时间保持高绝热性能非常重要。SiO ₂气凝胶的疏水改性的传统方法涉及气凝胶表面存在的有机官能团的改性，以取代原始的亲水性羟基官能团。但是，由于官能团的热损伤，SiO ₂气凝胶在高温（400°C）下失去了疏水性，这限制了气凝胶在高温领域中的应用。这项研究提出了一种新的疏水方法，即化学气相沉积，以在SiO ₂气凝胶表面上沉积一层疏水氮化硼（BN）。BN改性SiO ₂的表面疏水角气凝胶达到144.3°，疏水破坏温度升至700°C，表明疏水性稳定。该方法可用于通过在气凝胶表面层上沉积纳米BN膜来降低气凝胶表面能，同时保持未改性气凝胶的多孔结构。沉积的BN层可保护二氧化硅骨架。该层抑制二氧化硅结晶并改善气凝胶的热稳定性。