莫来石纤维增强SiO_2气凝胶隔热材料的制备

Preparation of SiO_2 Aerogels Heat Insulation Composites Reinforced by Mullite Fiber

以正硅酸乙酯(TEOS)为硅源,采用溶胶-凝胶及超临界干燥技术制备了莫来石纤维增强SiO2气凝胶隔热材料,并系统地研究了HF催化剂以及溶剂等制备因素对气凝胶品质的影响。结果表明:HF催化剂、H2O、乙醇和甲酰胺用量对TEOS的水解缩聚反应有较大影响,调节其配比可以制备具有不同密度的SiO2气凝胶隔热材料;添加甲酰胺可以调节凝胶内部网络结构,防止干燥时由于应力不均而开裂或破裂。

SiO2 aerogels heat insulation composites were prepared via sol - gel process and super drying technique using tetraethoxysilane（TEOS） as precursor, and studied the effects of many factors on gel character, such as the hydrofluoric acid catalyst, solvent and so on. The results showed that the dosage of the hydrofluoric acid catalyst, water, ethanol and formamide have important effects on hydrolyzation and condensation reaction, and SiO2 aerogels heat insulation composites with various density can be prepared by adjusting the proportion of these resactants. Adding formamide can adjust the network fabric within the gel, and prevent the gel from crazing or breaking in the process of drying because of the uneven stress.