Superhydrophobic, heat-resistant alumina-methylsilsesquioxane hybrid aerogels with enhanced thermal insulating performance in high humidity. Issue 8 (15th April 2023)

• Record Type: Journal Article
• Authors: Ren, Caixia; Yu, Yuxi
• Is Part Of: Ceramics international. Volume 49:Issue 8(2023)
• Page Start: 12625
• Page End: 12632
• Publication Date: 2023-04-15
• Subjects: Alumina-methylsilsesquioxane aerogel -- Superhydrophobicity -- Heat resistance -- Thermal insulating performance -- High humidity; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.12.125
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Heat-resistant alumina aerogels serve as prospective thermal insulating materials in the high-temperature fields, whereas the inherent hydrophilicity and thermal coarsening restrict their thermal insulating application. In this study, superhydrophobic, heat-resistant alumina-methylsilsesquioxane hybrid aerogels (AlMSAs) were prepared via in-situ sol-gel method combined with supercritical drying to overcome the aforesaid obstacles. The transformation from hydrophilicity to hydrophobicity is achieved by regulating the molar ratio of methyltriethoxysilane. The aerogel exhibits homogenous superhydrophobicity with contact angle reaching up to 152.6° when the molar ratio of Al to Si is 2 (AlMSA2). AlMSAs show superior heat resistance up to 1300 °C, suffering no α-Al2 O3 transition and minor grain growth. Quartz fiber reinforced alumina-based aerogel composite (QFAlMSA2) is prepared to study the thermal insulating performance in practical application. The thermal conductivity of QFAlMSA2 reversibly increases by 5.0% subject to 90% relative humidity (36 °C) for one month due to the superhydrophobicity. QFAlMSA2 exhibits a low thermal conductivity of 0.0542 W/(m·K) after being calcined at 1200 °C and a moderate temperature of 113 °C when exposed to a butane flame for 30 min. This study offers meaningful insights into developing alumina-based aerogel materials for high-moisture and high-temperature thermal insulations. Graphical abstract: Image 1 Highlights: Superhydrophobic alumina-based aerogels were prepared via in-situ sol-gel method. Heat resistance is improved by introducing silicon in alumina aerogel skeleton. Fiber-reinforced composite shows significantly enhanced thermal insulating performance in high humidity.