Abstract: Traditional SiO₂ aerogel composite materials experience obvious structural collapse at relatively high temperatures,leading to a sharp decline in thermal insulation property.On the basis of sol hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) as silicon source,large-particle silica sol was introduced as the second silicon source to form composite silicon source.SiO₂ aerogel composite materials were fabricated by compositing with mullite fibers,and their microstructure,thermal resistance were analyzed.The results show that the aerogel composite prepared with TEOS as single silicon source suffers remarkable structural collapse after heat treatment at 1 000 ℃,while the composite silicon source derived aerogel composite can retain its original three-dimensional network structure.The thermal conductivity of the aerogel composite with composite silicon source is 0.030 W·(m·K)^-1 at room temperature and 0.055 W·(m·K)^-1 at 1 000 ℃.After quartz lamp test at 1 000 ℃ for 1 000 s,the maximum temperature of the cold surface is only 82.8 ℃,which possesses favorable thermal insulation performance.

Key words: SiO₂ aerogel, silica sol, TEOS, heat insulation performance

摘要： 传统SiO₂气凝胶复合材料在较高的温度下会发生明显的结构坍塌现象,导致隔热性能明显降低。以正硅酸乙酯为硅源进行溶胶水解、缩聚的基础上,引入了大粒径硅溶胶为第二硅源形成混合硅源,与莫来石纤维复合后制备了SiO₂气凝胶复合材料,并分析了其显微结构与耐温隔热性能。结果表明,以正硅酸乙酯为单一硅源制备的气凝胶复合材料在1 000 ℃热处理后发生了明显的坍塌现象,而以混合硅源制备的气凝胶复合材料经1 000 ℃热处理后仍能保持原来的三维网状结构;混合硅源制备的气凝胶复合材料在常温下的热导率为0.030 W·(m·K)^-1,1 000 ℃下的热导率为0.055 W·(m·K)^-1,经1 000 ℃保持1 000 s石英灯测试,冷面最高温度仅为82.8 ℃,具有良好的隔热性能。

关键词: SiO₂气凝胶, 硅溶胶, 正硅酸乙酯, 隔热性能