低温真空环境下不同密度二氧化硅气凝胶复合材料隔热性能研究

以正硅酸乙酯、乙醇等为原料，采用溶胶-凝胶反应和超临界干燥工艺制备了密度分别为30、80、120、260、320 kg/m³的纤维增强二氧化硅气凝胶复合材料，分别在常压、25℃下以及真空、-130～25℃的条件下测定了所制备的气凝胶复合材料的导热系数，研究了复合材料的密度及组成对于气凝胶材料隔热性能的影响规律。结果表明：在常压、25℃条件下，在不同密度的气凝胶复合材料中，密度为120 kg/m³的气凝胶复合材料的导热系数最小(0.013 W/(m·K));密度为30、80、120 kg/m³的气凝胶复合材料的导热系数随密度增大而减小；密度为120、260、320 kg/m³的气凝胶复合材料的导热系数随密度增大而增大。在真空、-130～25℃的条件下，密度为120 kg/m³的气凝胶复合材料的导热系数最小；密度为30、80、120 kg/m³的气凝胶复合材料的导热系数随密度增大而减小。在130℃时，由于密度为320 kg/m³的气凝胶复...

Thermal insulation properties of silica aerogel composites with different densities in vacuum and low temperature condition

Fiber reinforced silica aerogel composites with densities of 30, 80, 120, 260 and 320 kg/m³ were prepared by sol-gel reaction and supercritical drying process using tetraethyl orthosilicate and ethanol as raw materials. The thermal conductivity of the prepared aerogel composites was measured at atmospheric pressure, 25 ℃ and vacuum, -130-25 ℃, respectively. The effects of density and composition of the composites on the thermal insulation properties of aerogel materials were studied. The results show that the thermal conductivity of aerogel composites with a density of 120 kg/m³ is the smallest (0.013 W/(m·K)) among aerogel composites with different densities under normal pressure and 25 ℃. The thermal conductivity of aerogel composites with density of 30,80,120 kg/m³ decreases with the increase of density. The thermal conductivity of aerogel composites with density of 120, 260, 320 kg/m³ increases with the increase of density. Under the condition of vacuum and -130-25 ℃, the thermal conductivity of aerogel composites with density of 120 kg/m³ is the smallest. The thermal conductivity of aerogel composites with density of 30, 80, 120 kg/m³ decreases with the increase of density. At 130 ℃, the aerogel composite with a density of 320 kg/m³ has the lowest thermal conductivity (0.006 2 W/(m·K)) due to the use of pre-oxidized fiber reinforced fibers with excellent radiation resistance.