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Funct. Mater. 2019; 26 (3): 541-547.

doi:https://doi.org/10.15407/fm26.03.541

Preparation of nano-SiO2 building aerogel thermal conductivity coatings and study on the factors of thermal conductivity

M.Liu

Institute of Civil Engineering of Weifang University of Science & Technology, 262700 Shouguang of Shandong, China.

Abstract: 

In order to study the factors affecting the thermal conductivity of silica aerogel coatings, silica aerogel microspheres were prepared by the sol-gel method and atomization technology. At the same time, a silica aerogel thermal insulation coating was prepared; the microstructure of the coating was observed by a scanning electron microscope (SEM), and the thermal conductivity of the silica aerogel insulation coating was measured by a Hot Disk thermal conductivity meter. The results of the SEM images showed that aerogel microspheres formed obvious agglomerates in the coatings, and when the aerogel volume fraction was high, the pores in the coatings increased. In addition, small diameter aerogel microspheres are easier to form agglomerates. Due to the large thermal resistance of the aerogel microspheres, the thermal conductivity of the aerogel insulation coatings decreases with the increase of the content of the aerogel microspheres. The agglomeration of the aerogel microspheres with uniform dispersion is not beneficial to the decrease of thermal conductivity, while the increase of pores is beneficial to the decrease of thermal conductivity of the coatings because of the high thermal resistance of air. The interfacial thermal resistance of small particles is larger than that of large ones, which leads to the low thermal conductivity of the thermal insulation coatings prepared by small particles. The bulk density of the aerogel microspheres increases with the mixed particle size, which is beneficial to decrease the thermal conductivity of the coatings.

Keywords: 
silica, aerogels, thermal insulation coatings, thermal conductivity.
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