二氧化硅气凝胶性能受热过程的影响  

Effect of Thermal Process on Microstructure and Physical Properties of Silica Aerogels

作　　者：刘光武[1,2] 周斌[1,2] 倪星元[1,2] 祖国庆[1,2] 

机构地区：[1]同济大学物理科学与工程学院,上海200092 [2]上海市特殊人工微结构材料与技术重点实验室,上海200092

出　　处：《同济大学学报（自然科学版）》2013年第7期1078-1083,共6页Journal of Tongji University:Natural Science

基　　金：国家自然科学基金(51102184;51172163;11074189);"十一五"国家科技支撑计划(2009BAC62B02)

摘　　要：成功地以水玻璃为硅源,经乙醇溶剂替换及六甲基二硅醚和盐酸的混合液对SiO_2湿凝胶表面基团改性后,常压干燥制备出低密度、高比表面积、超疏水、低热导率的高性能SiO_2气凝胶块体.SiO_2气凝胶在室温至400℃附近具有稳定的疏水性能,460℃附近气凝胶由疏水型完全转变成亲水型.重点研究了室温至400℃之间,SiO_2气凝胶的微观结构和物理性能受热处理过程的影响.SiO_2气凝胶即使经过400℃高温热处理后,仍能保持优异的疏水性能、较高的比表面积和较低的热导率等.Prepared with sodium silicate precursor, ethanol （Et0H） / hexamethyldisiloxane （HMDSO） /hydrochloric acid （HCL） as solvent exchange and surface modification agent, the crack-free and high hydrophobic silica aerogel monoliths were obtained. Silica aerogels possessed the superior properties, such as low density, high surface area, high hydrophobicity and low thermal conductivity. Silica aerogel monoliths maintained hydrophobic behavior up to a maximum temperature of 460℃ above which they become hydrophilic. After a thermal process changing from room temperature to 400 ℃, the final product still remained hydrophobic and presented good performance with the surface area of 530 m2 · g 1. Thermal conductivity coefficients of silica aerogelmonoliths changed from 0. 025 to 0. 049 W. （m. K） 1 as temperature increased from 25 ℃to 400 ℃, an excellent heat insulation effect during thermal process remained.

关 键 词：二氧化硅气凝胶 水玻璃 疏水性 热导率 高保 温 

分 类 号：TQ174[化学工程—陶瓷工业]