【摘要】 文中采用溶胶 凝胶法结合CO2 超临界一次溶剂抽提法制备SiO2 气凝胶。考察了干燥体系的平衡状态与CO2 +C2 H5OH二元系的关系对溶剂抽提率及SiO2 性能的影响 ,并采用XRD ,TG/DTA和TEM技术对样品进行了表征。结果表明 ,干燥体系处于CO2 +C2 H5OH二元系亚临界区域时 ,溶剂抽提率随温度 (40～ 6 0℃ )变化缓慢 ,干燥后样品中发现有机杂质 ;而处于CO2 +C2 H5OH二元系超临界区域时 ,溶剂抽提率高于亚临界区域 ,干燥后样品中未发现有机杂质 ,其样品近似球形 ,粒径在 2 0～ 30nm ,具有较好的网络结构。更多还原

【Abstract】 The sol-gel process and CO 2 supercritical drying technique were used to prepare silica aerogels. The relations of the equilibrium state of the drying system with the solvent extraction efficiency and SiO 2 performance were studied. The samples were characterized by TG/DTA, TEM and XRD techniques. The results show that the solvent extraction efficiency in the drying condition below the critical point of CO 2+C 2H 5OH system increases only slightly with the increase in temperature (40～60、℃) and organic impurities are found after drying. While the solvent extraction efficiency in the drying condition above critical point of CO 2+C 2H 5OH system is higher than that below the critical point of CO 2+C 2H 5OH system and no organic impurities are found after drying. The aerogel particles under supercritical conditions are similar to sphericity, and the particle size is 20～30、nm with good network.更多还原