Abstract:

Boehmite fibers were prepared using aluminum chloride hexahydrate as aluminum source by a hydrothermal method. Silica composite aerogels doped with boehmite fibers were then fabricated using methyltrimethoxysilane and tetraethoxysilane as silicon co-precursors after the sol-gel process and ambient pressure drying. The effect of the boehmite fiber content on the composite aerogel was studied. When the content（mass fraction） of boehmite fibers to silicon sol is 1%， the aerogel obtains the optimal mechanical properties， which can withstand 17.1% compressive strain， the maximum compressive strength is 1.12 MPa and the compressive modulus is as high as 2.57 MPa. The composite aerogels show low thermal conductivity of 0.0670 W·m^?1·K^?1 at 150 ℃. Moreover， it is found that the boehmite fiber can inhibit the sintering and phase transformation of silica particles at elevated temperature and thus enhance the high temperature resistance of silica aerogels. Accordingly， the silica-boehmite fiber composite aerogel can still maintain good thermal insulation performance and high mechanical strength at a high temperature of 1100 ℃.

Key words: Silica aerogel, Boehmite fiber, High temperature resistance