The impact of aluminum oxide deposition on the high-temperature resistance of silica aerogels

Silica aerogel (SA) was synthesized through the sol-gel process followed by ambient pressure drying, with aluminum-deposited silica aerogel (ASA) subsequently produced via aluminum deposition using an AlCl₃·6H₂O hydrolysis solution. This study examined the impact of deposition time and calcination temperature on ASA’s characteristics. Compared to the non-aluminum-deposited SA, ASA with 12 h of deposition time (ASA-12h) showcased a significant increase in specific surface area, reaching 675m² ∙ g⁻¹ at room temperature. Post-calcination at 800 °C and 1000 °C resulted in specific surface areas of 613m² ∙ g⁻¹ and 265m² ∙ g⁻¹, respectively, markedly surpassing those of SA (240 m²∙g⁻¹ at 800 °C and 16m² ∙ g⁻¹ at 1000 °C). The results demonstrate that during the aging process, the deposited aluminum is coated by the aging solution, enabling it to remain stable and distribute uniformly. This deposition not only increases the particle size but also enhances structural stability. Furthermore, the formation of new Si-O-Al bonds improves the thermal stability of the silicon dioxide lattices. These insights pave the way for the industrial production of aerogels that are resistant to high temperatures.