二氧化硅溶胶的制备及性能影响研究

以正硅酸乙酯、水、乙醇和酸性催化剂为原料，制备了SiO2溶胶。研究了催化剂的种类、反应温度、反应时间、添加剂等因素对SiO2溶胶性能的影响。实验结果表明：在H^＋]相同的条件下，酸催化剂对溶胶粘度的影响为：HF〉HCI〉HN03〉H2S04〉HAC，对凝胶时间的影响为：HAC〉H2S04〉HC1〉HN03〉HF，几种溶胶固含量的大小为：H2S04〉HN03〉HCl〉HAC，制备二氧化硅膜用硅溶胶较适合采用盐酸或硝酸作为催化剂；随着反应温度的升高，溶胶的粘度、固含量和粒径均逐步增大，凝胶时间则缩短；随着反应时间的延长，溶胶的粘度、固含量以及粒径逐步增大，凝胶时间则变短；向在溶胶中加入DMF后，溶胶粘度、固含量变小，凝胶时间延长，SiO2粒子的粒径增大。

Preparation of Silica Sol and Effect of Preparation Conditions on Its Properties

Silica sol was prepared using TEOS,water,ethanol and acid catalyst as the materials.The effects of catalyst,reaction temperature,reaction time and additives on the properties of silica sol were investigated.The results showed that the effect of acid catalyst on the viscosity of silica sol is HF> HCl >HNO3 >H2SO4 >HAC,the effect on gel time of sol is HAC > H2SO4 > HCl > HNO3> HF,the effect on turbidity and solid content is H2SO4 > HNO3 > HCl> HAC when in sol is equal.It is appropriate to select HCl or HNO3 as the catalyst to prepare sol for silica membrane.With the reaction temperature increased the viscosity,solid contents and particle size of silica sol increases step by step and gel time decreases.With the reaction time increased the viscosity,solid contents and particle size of sol increases step by step and gel time decreased.Adding DMF into sol,the viscosity and solid contents decrease,gel time increases and particle size of sol increases.