采用溶胶-凝胶法及超临界流体干燥技术制备了SiO_2气凝胶,系统地考察了醇硅比、水硅比、体系pH值及HF用量等制备条件对SiO_2气凝胶孔径分布及孔型结构的影响.结果发现,随着水量的增加气凝胶的孔径分布逐渐变窄,孔型趋于一致.乙醇不参与溶胶-凝胶反应,醇硅比的增加不会对SiO_2气凝胶的孔径分布和孔结构产生剧烈影响.在较低pH值或弱碱性范围内,pH值对孔型结构的影响较小,制得的气凝胶孔径分布较窄,孔型均一,当pH值＞8.5以后,不利于气凝胶网络结构的形成和均匀分布.HF用量的减少会使得气凝胶的孔径和孔型趋于向宽分布和多样化变化,但变化幅度不是太大.
SiO_2-aerogel was prepared via sol-gel method and ethanol supercritical drying. The influence of the pH value of the original hydrogel, the ratio of EtOH/TEOS, H_2O/TEOS and HF/TEOS on the pore size distribution and pore structure of aerogel were investigated. The results showed that the pore size distribution and pore structure of aerogel were tending to become homogeneous with the increase of the water. For the diluted function of the ethanol, the effect of it on the pore size distribution and pore structure was moderate with the increase of the ethanol. When the pH value was less than 8.5, the pH value has a mild influence on the pore structure of aerogel. But when the pH value was more than 8.5, the effect become intense, the pore size distribution broadens out rapidly at this point. The content of HF has a mild influence on SiO_2-aerogel, as the decrease of HF the pore size distribution tends to become wide tardily.
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