Quartz fiber reinforced Al2O3-SiO2 aerogel composite with highly thermal stability by ambient pressure drying

A low-cost and high-performance quartz fiber/Al2O3-SiO2 aerogel (QF/ASA) composite insulation material has been successfully prepared by vacuum filtration molding and sol-gel impregnation following surface-modified ambient pressure drying (APD). The macroporous in the quartz fiber perform are filled by Al2O3-SiO2 aerogels with a large amount of mesoporous. The morphology, microstructure, thermal conductivity and thermal stability of the QF/ASA composite were investigated. Compared to the fiber/aerogel materials dried by supercritical drying, the composite exhibits similar low density (0.36 g·cm−3), high specific surface area (580.5 m2·g−1), low thermal conductivity (0.049 W·m−1·K−1) at room temperature. The compressive strength of the composite up to 0.85 MPa which is approximately triple as much as that of fiber perform. After being heated at 600 to 1100 °C, the specific surface area of composite aerogel decrease from 578.0 to 113.6 m2·g−1 and the linear shrinkage is almost zero. The XRD patterns show that mullite (3Al2O3·2SiO2) appeared in the Al2O3-SiO2 aerogel after heat-treatment at 1100 °C, which is consistent with the molar ratio of silica and alumina of 2:3.