超低密度SiO2气凝胶的制备及成型研究
Preparation and molding of ultralow-density silica aerogels
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摘要: 以正硅酸乙酯(TEOS)为硅源，采用酸碱二步催化溶胶-凝胶法，结合超临界干燥技术制备了超低密度SiO2气凝胶,最低密度为3.4 mg/cm3；进一步结合成型工艺，在解决了模具设计和脱模技术后制备了具有不同密度的柱状和微型套筒样品，密度10～50 mg/cm3。研究了水、催化剂、稀释剂对二步溶胶-凝胶过程的影响，获得了制备低密度SiO2气凝胶的最佳条件。利用扫描电镜、孔径分布及比表面积测试仪等对SiO2气凝胶微结构进行了研究。结果表明，获得的超低密度SiO2气凝胶具有较好的纳米网络，平均孔径18.9 nm，还具有高比表面积898 9 m2/g。Abstract: The two-step（acid-base）sol-gel process was used to prepare SiO2 aerogels, with TEOS as the precursor. The influence of catalyst, water and solvent on the sol-gel process was investigated to optimize the experimental conditions. Ultralow-density silica aerogels with densities as low as 3.4 mg/cm3, solid cylinders and shells at various densities(10～50 mg/cm3) were made. Scan electron microscope, pore size distribution techniques were used to characterize the morphology and pore structure of the silica aerogel. The results show that the ultralow-density silica aerogel has good nanostructure with average pore size of 18.9 nm and specific surface area of 898.9 m2/g.
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Key words:
- ultralow-density /
- silica aerogels /
- two-step process /
- sol-gel process
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