溶胶共凝法制备准连续密度梯度SiO2气凝胶

针对气凝胶在航空航天领域的应用需求,为了进一步拓展单一密度气凝胶的应用范围,对密度梯度SiO2气胶的制备进行了研究.采用自建密度梯度制备成型装置,以正硅酸乙酯为有机硅源,经溶胶共凝工艺,结合CO2超临干燥技术,获得密度范围在60~160 mg/cm3的准连续密度梯度SiO2气凝胶.采用光学显微镜、扫描电子显微镜、X线相...

Fabrication of Graded Density SiO2 Aerogel via Sol-Co-Gelation Techniques

For the application requirement in aerospace and further expanding the application field of aerogel, the fabrication of gradient density aerogel SiO₂ has been researched in this paper. By a self-built device, a continuously graded silica aerogel is fabricated via special sol-co-gelation techniques, with tetraethoxysilane (TEOS) as the organic precursor and by a supercritical drying process. Its density ranges from 60 mg/cm³ to 160 mg/cm³. Scan electron microscope, X-ray phase contrast method and optical microscopy are used to characterize the graded density silica aerogel prepared. Compared with the graded density silica aerogel produced by layer-by-layer gelation techniques, the sol-co-gelation techniques smooth out density mutation and increase the interdiffusion between adjacent layers, which makes density change tend to be more continuous. The gradient density aerogel fabricated by such a method expands greatly the application of conditional aerogel. It can potentially be used in many fields such as acoustic impedance matching and interstellar particles collection.