SiO_2气凝胶/纤维复合材料制备工艺研究

STUDY ON THE PREPARATION TECHNIQUE OF SiO_2 AEROGELS/FIBER COMPOSITES

以正硅酸乙酯(TEOS)为硅源,盐酸、氨水为催化剂,采用两步法及常温干燥技术制备了纤维增强SiO2气凝胶隔热材料,研究了H2O、EtOH、pH值及温度等制备条件对溶胶-凝胶过程的影响。H2O对凝胶化过程的影响比较复杂,凝胶时间随其用量的增加先减后增,转折点处水硅摩尔比为4～6之间;溶剂EtOH对凝胶化过程有明显的抑制作用,凝胶时间随其用量的增加而增加;pH值对凝胶化过程也有比较明显的影响,pH值越高凝胶化过程越快;随着温度的升高凝胶化过程也越快。

SiO2 aerogels/fiber composites were prepared by sol-gel process and drying under ambient pressure ,this study used tetraethoxysilane （TEOS） as precursor ,chlorhydric acid and hartshorn as catalyst, respectively. The effects of many factors on the sol-gel process were studied, such as solvent, pH, temperature and so on. The result showed that the effect of water on the process of gelation was complex, and he gelation time decreases first and then increases with the increases of the water dosage, the best ratio range of water to TEOS fails between 4 ： 1 to 6 ： 1 the solvent ethanol have restraint on the process of gelation evidently, and the gelation time increases with the increase of the ethanol dosage the gelation time decreases with the increase of temperature and pH.