Fabrication of flexible silica aerogel composite blankets from an aqueous fumed silica-based slurry

Silica aerogels exhibit considerable potential for thermal insulation applications owing to their low thermal conductivity. However, they generally possess poor mechanical properties and need to be mechanically enhanced while maintaining their low thermal conductivity. In this study, commercial fumed silica and methyltrimethoxysilane were used as the silica sources and water and ethanol were used as solvents to form a slurry. Consequently, silica aerogel monoliths (SAMs) were prepared through ambient drying without additional surface modification or solvent replacement. The resulting SAM maintained a typical nanopore structure and exhibited low density (0.24 g cm−3), shrinkage (4%), and thermal conductivity (0.046 W m−1 K−1). The slurry was impregnated with fiber blankets via roller pressing, and silica aerogel blankets (SABs) were prepared through thermal solidification of the slurry and ambient drying. The prepared SABs exhibited good flexibility and mechanical properties, facilitating their installation and application for thermal insulation and considerably reducing production cycles and costs. In addition, controlling the particle size and mass fraction of opacifiers decreased the high-temperature thermal conductivities of SABs owing to the nanopore structure and low shrinkage of SAMs, and the thermal conductivity of the optimized SAB at 800°C was as low as 0.054 W m−1 K−1.