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.
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Acknowledgments
This work was supported by National Natural Science Foundation of China (50802064, 11074189), New Century Excellent Talents in University of China (NCET-08-0405), Shanghai Committee of Science and Technology (0952nm00900, 0952nm00700), National Science and Technology Support Program (2009BAC62B02).
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Gui, JY., Zhou, B., Zhong, YH. et al. Fabrication of gradient density SiO2 aerogel. J Sol-Gel Sci Technol 58, 470–475 (2011). https://doi.org/10.1007/s10971-011-2415-x
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DOI: https://doi.org/10.1007/s10971-011-2415-x