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以正硅酸乙酯为硅源,采用两步溶胶-凝胶法结合超临界干燥技术制备出了块状无裂纹SiO2气凝胶,体积密度在50kg.m-3和300 kg.m-3之间,样品尺寸约为300mm×300mm×50mm。热学测试表明,常温常压下体积密度大约为100kg.m-3的样品导热系数为0.020 W/m.K,并采用XRD、SAXS、BJH和SEM等其他方法对典型样品(100kg.m-3)进行了测试。测试结果表明,SiO2气凝胶是非晶态的,并且具有纳米多孔结构(骨架颗粒平均粒径为6.8nm,孔径主要集中在10~20nm范围内,而且所有孔径都在70nm以内)。因而可作为具有一定潜在应用价值的块状纳米孔超级绝热材料。
Block-like crack-free aerogels were prepared by two-step sol-gel method combined with supercritical drying using ethyl orthosilicate as silicon source with a bulk density of 50 kg.m-3 and 300 kg.m-3 The sample size is about 300 mm × 300 mm × 50 mm. Thermal tests show that the sample with a bulk density of about 100kg.m-3 at room temperature and normal pressure has a thermal conductivity of 0.020 W / mK and the typical sample (100kg.m-3) is subjected to other methods such as XRD, SAXS, BJH and SEM The test. The test results show that the SiO2 airgel is amorphous and has a nano-porous structure (the average particle size of the framework particles is 6.8 nm, the pore size mainly lies in the range of 10 to 20 nm, and all the apertures are within 70 nm). Therefore, it can be used as a block nanoporous super thermal insulation material with certain potential applications.