Effect of the thermal treatment on microstructure and physical properties of low-density and high transparency silica aerogels via acetonitrile supercritical drying |
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Authors: | Guangwu Liu Bin Zhou Ai Du Jun Shen Qiujie Yu |
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Affiliation: | 1. Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Institute of Physical Science and Engineering of Tongji University, Shanghai, 200092, People’s Republic of China
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Abstract: | In this paper, we reported the experimental results about the effect of the thermal treatment on microstructure and physical properties of low-density and high transparent silica aerogels. From our results, with tetramethyl orthosilicate as precursor and via acetonitrile supercritical drying process, silica aerogel monolith was obtained possessing the properties as low-density (0.018 g/cm3), high surface area (923 m2/g), high optical transparency (87.9 %, 800 nm). It should be noted that high transparency of silica aerogel can be maintained up to 600 °C (91.5 %, 800 nm). The mechanical properties of silica aerogel decreased with increasing heat treated temperature to 600 °C, and silica aerogels still maintained crack-free monoliths completely and possessed high homogeneous density even after 600 °C thermal treatment. Furthermore, thermal conductivity of the monoliths at desired temperatures was analyzed by the transient plane heat source method. When the temperature flowed from 25 to 600 °C, thermal conductivity coefficients of silica aerogels changed from 0.021 to 0.065 W (m K)?1, revealed an excellent heat insulation effect in high-temperature area. Currently, the specific process developed for low-density aerogels affected by thermal treatment has not been reported in previous literature. |
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