摘要
以正硅酸乙酯(TEOS)为硅源,采用酸碱两步催化溶胶-凝胶法和CO_2超临界干燥技术成功制备出完整的厘米级SiO_2气凝胶球体。当配比条件为TEOS∶EtOH∶H_2O=1∶10∶4时制备的SiO_2气凝胶球体具有典型的纳米多孔网络结构。采用扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱仪(FT-IR)、孔径分布及比表面积测试仪(BET)、纳压痕技术对SiO_2气凝胶球体的表面形貌、内部结构、化学成分、比表面积、孔径分布及力学性能进行研究分析。研究表明:低温有利于制备出完整的厘米级SiO_2气凝胶球体。随着凝胶温度的增加,SiO_2气凝胶球体样品的收缩率逐渐增加,而孔隙率和比表面积逐渐减小。当凝胶温度为-5℃时,厘米级SiO_2气凝胶球体样品的平均孔径为24.8 nm,孔体积为4.9 m^3/g,比表面积高达1004.38 m^2/g,密度为0.104 g/cm^3,收缩率约为16.2%,孔隙率约为95.3%,弹性模量和硬度最大分别为8.79 MPa与5.24 MPa。
The prefect sphere silica aerogel with centimetre-sized was prepared by supercritical CO_2 drying with TEOS（ ethyl orthosilicate） as silica source in this paper. It was found that the optimum preparation conditions were gained as follows： the amount-of-substance ratio of TEOS ∶ EtOH ∶ H_2O = 1 ∶ 10 ∶ 4. The sphere silica aerogel with typical nanometer porous network structure was prepared under this condition.The surface morphology,microstructure,chemical components,adsorbability and mechanical properties of silica aerogel were characterized by SEM,TEM,FT-IR,BET and nanoindentation techniques. It was found that low temperature can contribute to prepare centimetre-sized sphere silica aerogel. With the increase of gel temperature,the shrinkage rate of sphere silica aerogel gradually increased,while the porosity and specific surface area decreased. When the gel temperature at-5 ℃,the average pore size was 24. 8 nm,the pore volume was 4. 9 cm^3/ g,the specific surface area was 1004. 38 m^2/ g,the apparent density was 0. 104 g/cm^3,and the shrinkage rate was 16. 2%,the porositywas 95. 3%,the maximum value of hardness and modules is 8. 79 MPa and 5. 24 MPa,respectively.
出处
《硅酸盐通报》
CAS
CSCD
北大核心
2017年第2期635-641,共7页
Bulletin of the Chinese Ceramic Society
基金
四川省教育厅项目(14zd1122)
