Preparation of Al2O3-SiO2 aerogel by ambient pressure drying for thermal insulation application

Al2O3-SiO2 aerogel (ASA) was prepared by convenient ambient pressure drying using inexpensive AlCl3 center dot H2O as precursor, and silicon was deposited during the aging of aluminum gel. To explore the influence of Chloride ion on the property of ASA, ion exchange technology was used to remove the Chloride ion in the aluminum sol. ASA exhibits a low thermal conductivity of 0.029 W m(-1) K-1 at room temperature, and the specific surface area of Cl-free ASA after heat-treated at 1200 degrees C is 95.2 m(2)/g, which is higher than that of the chlorine-containing aerogel (11.4 m(2)/g), showing enhanced thermal stability of ASA. Analysis of XRD and XPS indicate that the removal of chloride ions makes it more difficult for ASA to establish Al-O-Si groups during the aging process, so the gamma-Al2O3 and cristobalite phase do not transform to mullite phase at 1200 degrees C. Due to the better thermal stability of ASA, it has great potential for high-temperature applications in the fields of insulation, thermal protection materials, and building external wall thermal insulation.

Automated summary

In this study, Al2O3-SiO2 aerogel is prepared by ambient pressure drying method using inexpensive AlCl3 · H2O as a precursor, with silicon being deposited during the aging of aluminum gel. Ion exchange technology is used to remove chloride ions in the aluminum sol to explore their influence on the properties of ASA. ASA exhibits a low thermal conductivity at room temperature and shows enhanced thermal stability compared to the chlorine-containing aerogel. XRD and XPS analysis indicate that the removal of chloride ions hinders the formation of Al-O-Si groups during the aging process, preventing the transformation of gamma-Al2O3 and cristobalite phases to mullite phase. ASA has great potential for high-temperature applications in insulation, thermal protection materials, and building external wall thermal insulation.