Fabrication of gradient density SiO₂ aerogel

Author： Gui Jia-Yin Zhou Bin Zhong Yan-Hong Du Ai Shen Jun

ISSN： 0928-0707

Source： Journal of Sol-Gel Science and Technology, Vol.58, Iss.2, 2011-05, pp. : 470-475

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Abstract

With tetraethoxysilane as the organic precursor, gradient density aerogels were fabricated by three different methods: layer-by-layer gelation, sol-co-gelation and continuous formation technics. Through layer-by-layer method, a 5-layer graded density silica aerogel whose density ranges from 50 to 200 mg/cm³ was obtained, but it existed a dense skin between adjacent layers which could result in density mutation in the interface. In order to optimize its interface character, sol-co-gelation technique was created to improve the interdiffusion and smooth out the density mutation via a self-built device. Finally, on the base of the device and sol-co-gelation technics, a continuous formation process was developed to fabricate the completely gradient density silica aerogel. Optical microscope and X-ray phase contrast method were used to characterize the samples prepared by three different technics and comparatively research their interface feature.