酸碱条件对水玻璃为源制备SiO₂气凝胶的影响

王冬冬,孙小飞,王自强,王泽华,王 刚,李红霞

(中钢集团洛阳耐火材料研究院有限公司 先进耐火材料国家重点实验室,河南 洛阳 471039)



摘要:

以廉价的工业水玻璃为凝胶前躯体,柠檬酸为凝胶促进剂,使用溶胶-凝胶与CO₂超临界干燥工艺制备了块状的SiO₂气凝胶,并探讨了酸性和碱性条件对所制备SiO₂气凝胶结构与性能的影响.实验结果表明:水玻璃在酸性条件(pH≈4)和碱性条件(pH≈10)下均可以制备出完整、无开裂的二氧化硅气凝胶块体样品,酸性和碱性环境对水凝胶和最终SiO₂气凝胶结构和性能的影响较大.酸性条件下获得的水凝胶呈透明块体,而碱性条件下所得水凝胶为白色不透明体.与碱性条件下制备的SiO₂气凝胶相比,酸性条件下所得气凝胶具有更高的比表面积、较大的密度以及尺寸较小的胶体粒子.

关键词:  SiO₂气凝胶  酸性条件  碱性条件  比表面积

DOI：10.11951/j.issn.1005-0299.20130214

分类号:

基金项目:国家高技术研究发展计划资助项目(No.2009AA032503)；国家自然科学基金青年基金资助项目(No.51002145)；国家重点基础研究发展规划资助项目(No.2010CB735810).



Effects of acidic and alkaline conditions on the properties of silica aerogel monoliths using sodium silicate as precursor

WANG Dong-dong,SUN Xiao-fei,WANG Zi-qiang,WANG Ze-hua,WANG Gang,LI Hong-xia

(State Key Laboratory of Advanced Refractories,Sinosteel Luoyang Institute of Refractories Research Co.,Ltd.,Luoyang 471039,China)

Abstract:

The silica aerogel monoliths were prepared by sol-gel method and supercritical drying technique,using water-glass as the precursor and citric acid as the catalyst.The effects of acidic and alkaline condition on the microstructure and properties of silica aerogel monoliths were discussed in detail.The results show that the wet gel monoliths can be prepared in acidic(pH≈4) and alkaline(pH≈10) conditions which have significant effect on the properties of silica aerogels.The wet gel monoliths prepared in acidic condition are transparent,while the wet gel monoliths obtained in alkaline condition have a milky appearance.The silica aerogel monoliths prepared in acidic condition possess higher specific surface area,larger density and smaller-size colloidal nano particles compared with those obtained in alkaline condition.

Key words:  SiO₂ aerogel  acidic condition  alkaline condition  specific surface area