石英玻璃纤维/气凝胶复合材料的热导率计算及优化  

Calculation and Optimization of Thermal Conductivity of Fused Silica Fiber/Aerogel Composites

作　　者：杨建明[1] 吴会军[1] 钟支葵 何石泉[1] 王沫然[2] 

机构地区：[1]广州大学土木工程学院,广州510006 [2]清华大学工程力学系,北京100084

出　　处：《材料导报》2016年第10期139-143,147,共6页Materials Reports

基　　金：广东省自然科学杰出青年基金(S2013050014139);广州市羊城学者科研项目(1201561560)

摘　　要：纤维含量和直径是影响纤维/气凝胶复合材料热导率的重要参数。采用常压干燥工艺实验制备了石英玻璃纤维/SiO_2气凝胶复合材料,基于材料微观结构表征结果建立了纤维/气凝胶复合材料总体热导率的计算模型,研究了纤维含量和纤维直径对复合材料热导率的影响规律。通过二元优化(即同时优化纤维体积分数和直径)获得了复合材料的最小总体热导率,与单一优化纤维含量或纤维直径相比总体热导率可分别减少50%和20%(以1000K为例);并探讨了在不同温度条件下复合材料中最优纤维含量和纤维直径的变化规律,发现随温度升高最优纤维含量增大而最优纤维直径减小。研究结果可用于指导纤维/SiO_2气凝胶复合材料的结构设计和性能优化,促进气凝胶复合材料在航空航天、工业、建筑等领域的节能应用。The content and diameter of fibers have significant effect on the thermal conductivity of the fiber/aerogel composites.A series of fused silica fiber/aerogel composites were prepared via ambient pressure drying.Based on the microstructure characterization of fused silica/SiO_2 aerogel composites,a theoretical model was built to predict the total thermal conductivity of the composite.The effects of content and diameter of fused silica on the thermal conductivities were investigated,and the minimum total thermal conductivity of the composite was obtained by optimizing content and diameter of fused silica simultaneously.The minimum total thermal conductivity derived via simultaneous optimization was 20%lower than that derived via individually optimizing the fiber volume fraction at diameter of 8μm and 50%lower than that by individually optimizing the fiber diameter at volume fraction of 3%as the temperature was1000 K.The variations of optimized fiber content and diameter with temperature were investigated,indicating a rising optimized volume fraction and a declining optimized diameter as the temperature was increased.The optimization results provide guidance for structure design and properties optimization of fused silica/SiO_2 aerogel composites and consequently for promoting its energy conservation application to aerospace,industry,construction and other fields.

关 键 词：气凝胶 复合材料 热导率 衰减系数 优化 

分 类 号：TK124[动力工程及工程热物理—工程热物理]