酸碱对正硅酸乙酯水解液凝胶速度的影响

Impact of Acid and Base on the Gelling Process of Tetraethoxysilane Hydrolysate

目的:研究酸碱对正硅酸乙酯水解液的影响。方法:通过对正硅酸乙酯水解原液分别加入不同浓度的盐酸和氨,观察其发生凝胶的速度。结果:①正硅酸乙酯水解液随着酸加入量的增加,发生凝胶的速度缩短,胶体的强度也增加。不加入盐酸则凝胶速度明显变慢。②正硅酸乙酯水解液随着氨加入量的增加,凝胶时间明显缩短,凝胶速变快。但氨加入量过多时,瞬间便出现沉淀。结论:正硅酸乙酯水解产物的缩合-聚合反应与酸碱浓度有关,在碱性条件下比酸性快,且与氨的浓度密切相关。我们可以通过控制酸碱的用量来调节其凝胶的速度和耐火材料所需的流动性。

Objective：To study the effect of acid-base on gelling speed of tetraethoxysilane（TEOS）hydrolysate.Methods：The hydrolysates of TEOS stock solution were added into different concentrations of hydrochloric acid and ammonia respectively,to observe the speed of gelling.Results：①As the quantity of acid added increased,the gelling process of TEOS hydrolysates was shortened,and the hardness of gel was also increased.② More ammonia added could slow the gelling process obviously,but precipitation appeared suddenly as pH value increased too quickly.Conclusion：The pH value has impact on the condensation-polymerization reactions of hydrolysis products of TEOS,and the gelling process was shorten more significantly by ammonia than by acid.Changes of pH values could modify the gelling process and flowability of refractory matter.