硬硅钙石二次粒子增强 SiO2气凝胶等效热导率

摘要

Microstructure of aerogel skeleton is described with the fractal‐intersecting sphere model . The true microstructure of fiber wall of secondary particles is processed based on fractal theory .Then the model for calculating the effective thermal conductivity of silica aerogel composite reinfored by secondary particles is established with consideration of the contact thermal resistance between parti ‐cles and influence of radiative heat transfer .The thermal conductivity of aerogel composite is mea‐sured .The model computing values and experimental measuring results show that they match well , which proves that the model is correct .The effect of density of secondary particles ,density of aerogel , density of composite thermal insulation materials and diameter of secondary particles on the effective thermal conductivity of composite thermal insulation material is analyzed .%首先，采用分形交叉球杆模型描述气凝胶骨架微观结构，并引入分形理论处理二次粒子纤维壁复杂的微观形貌，在综合考虑二次粒子间的接触热阻和辐射传热的影响上，建立了二次粒子增强气凝胶的等效热导率计算模型；然后，实验测定了该材料的热导率，测量值与计算值吻合良好，验证了该模型的正确性；最后，分析了二次粒子密度、粒径、气凝胶密度以及复合密度等对等效热导率的影响。