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

Abstract

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.

摘要

二氧化硅气凝胶由于其低导热率在隔热应用方面具有巨大的潜 力. 然而, 它们通常具有较差的机械性能, 需要在保持低热导率的同时 增强机械性能. 本研究以商业化气相二氧化硅和甲基三甲氧基硅烷为 硅源, 并以水和乙醇为溶剂形成浆料. 基于此, 二氧化硅气凝胶块体 (SAMs)可通过常压干燥进行制备, 且无需额外的表面改性或溶剂置换. 制备的SAMs保持了典型的纳米孔结构, 具有低密度(0.24 g cm⁻³)、收 缩率(4%)和热导率(0.046 W m⁻¹ K⁻¹). 通过辊压将浆料浸渍到纤维毡 中, 并通过浆料热固化和常压干燥制备出二氧化硅气凝胶毡(SABs). 制 备的SABs具有良好的柔韧性和机械性能, 便于安装和隔热应用, 并显著 减少了生产周期和成本. 此外, 基于SAMs的纳米孔结构和低收缩率, 通 过调控遮光剂的粒径和质量分数进一步降低了SABs的高温热导率, 优 化后的SABs在800°C的热导率低至0.054 W m⁻¹ K⁻¹.