溶胶-凝胶法制备SiO_2的溶胶粘度性能研究

STUDY ON THE VISCOSITY OF SILICA SOL FOR PREPARING SiO_2 FILM BY SOL-GEL PROCESS

以正硅酸乙酯为前驱体,硝酸为催化剂制备了SiO2溶胶.研究了反应物比例、反应时间、反应温度、陈化条件及添加剂对溶胶粘度的影响.结果表明,EtOH/TEOS摩尔比增大,溶胶粘度减小;H2O/TEOS摩尔比增大,溶胶粘度先增大后减小,H2O/TEOS=9.6左右时粘度最大;pH<2时,HNO3/TEOS摩尔比增大,溶胶粘度增大;反应时间的延长及反应温度的升高都会促使溶胶粘度增大;低温陈化可以大大提高溶胶的贮存性,陈化时间延长,溶胶粘度开始变化缓慢,接近凝胶点时急剧增大;DMF加入量增大,溶胶粘度减小.

Silica sol was prepared using TEOS as the precursor and HNO3 as the catalyst by sol-gel process. The effects of the ratio of the reactants, reaction temperature,reaction time, stored conditions and DMF on the viscosity of SiO2 sols were inspected during the sol-gel processing. The results showed that with the increasing of EtOH/TEOS molar ratio, the viscosity of sols reduced. With the increasing of H2O/TEOS molar ratio, the viscosity of silica sol firstly increases and then decreases. When H2O/TEOS is about 9. 6, the viscosity attained to the maximum. With the increasing of HNO3/TEOS molar ratio, the viscosity of sols increased when pH value is less than 2. Reaction tempeture raising and reaction time increasing could increase the viscosity. Sols could be stored longer at low temperature, with the raising of storing time, the viscosity of silica sol firstly changed slowly and changed rapidly at gelation point. Adding DMF to the Sols could reduce the viscosity.