Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aeroge...Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.展开更多
Cesium tungsten bronze （CsxW03） powders were synthesized by hydrothermal reaction at 190 ℃ by using sodium tungstate and cesium carbonate as raw materials, and the effects of N2 annealing on the microstructure and ...Cesium tungsten bronze （CsxW03） powders were synthesized by hydrothermal reaction at 190 ℃ by using sodium tungstate and cesium carbonate as raw materials, and the effects of N2 annealing on the microstructure and near-infrared （NIR） shielding as well as heat insulation properties of CsxW03 were investigated. The results indicated that the synthesized CsxW03 powders exhibited hexagohal CSo.32WO3 crystal structure, and subsequent N2 annealing could further improve the crystallinity of CsxW03 particles. Moreover, the NIR shielding and heat insulation properties of CsxW03 could be further improved after N2 annealing at appropriate temperature for a period of time. Particularly, the 500 ℃-annealed CsxW03 products in the N2 atmosphere showed the best NIR shielding and heat insulation properties. When the N2 annealing temperature was higher than 700 ℃, the NIR shielding properties decreased again. The 800 ℃-annealed samples in the N2 atmosphere showed higher visible light transmittance, however, the NIR shielding properties were lower than that of the non-annealed samples.展开更多
文摘Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.
基金financially supported by the National Natural Science Foundation of China(No.51278074)the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(the[42nd,20111139])
文摘Cesium tungsten bronze （CsxW03） powders were synthesized by hydrothermal reaction at 190 ℃ by using sodium tungstate and cesium carbonate as raw materials, and the effects of N2 annealing on the microstructure and near-infrared （NIR） shielding as well as heat insulation properties of CsxW03 were investigated. The results indicated that the synthesized CsxW03 powders exhibited hexagohal CSo.32WO3 crystal structure, and subsequent N2 annealing could further improve the crystallinity of CsxW03 particles. Moreover, the NIR shielding and heat insulation properties of CsxW03 could be further improved after N2 annealing at appropriate temperature for a period of time. Particularly, the 500 ℃-annealed CsxW03 products in the N2 atmosphere showed the best NIR shielding and heat insulation properties. When the N2 annealing temperature was higher than 700 ℃, the NIR shielding properties decreased again. The 800 ℃-annealed samples in the N2 atmosphere showed higher visible light transmittance, however, the NIR shielding properties were lower than that of the non-annealed samples.
