AlN/橡胶复合材料等效热导率数值计算∗

摘要

In this paper different aluminum nitrate/rubber structures are reproduced by using computer and then a 3D lattice Boltzmann method was proposed to compute the effective thermal conductivity of the composites. Aluminum nitrate/rubber composite was prepared,and the thermal conductivity of the composite with different filling quantity was tested.The model was verified by comparing the predicted and the practical thermal conduc-tivity.This article use LBM calculated results compared with the results of the Maxwell equation,the Brugge-man equation,the Nielsen equation and the experimental data,it showed that the present results agree well with the Maxwell model,and compared with Bruggeman model and Nielsen model,it was more similar to ex-perimental data.Then the effects of the particle size and distribution mode of aluminum nitrates on the effective thermal conductivity of the composites were quantified.The result showed that the thermal conductivity of the composites filled with small diameter aluminum nitrates were larger over a certain range of volume fraction,the thermal conduction network first formed in the composites filled with big aluminum nitrates and significantly improved the thermal conductivity when the volume fraction reached 20%.The composite with random spatial distribution shows higher thermal conductivity than that with uniform spatial distribution,it illustrated that the thermal conductivity of composites can be significantly different due to different particle spatial distributions.%利用计算机生成不同的AlN/橡胶复合材料等效结构单元，基于三维格子玻尔兹曼模型计算了复合材料的等效热导率。实验制备了 AlN/橡胶复合材料，并测定了不同填充量下复合材料的热导率，用以验证模型的有效性。将 LBM 计算结果与实验结果及Maxwell、Bruggeman、Nielsen 等模型进行了比较，发现本文数值计算结果与 Maxwell 模型吻合较好，相比较于 Bruggeman 模型与 Nielsen 模型更加接近实验值。研究了AlN 颗粒尺寸及分布方式对复合材料导热性能的影响。结果表明，一定体积分数范围内，粒径较小的AlN颗粒填充橡胶复合材料的等效热导率较大，当体积分数增大到20％，粒径较大的复合材料内先开始形成导热网络，大大提高了热导率；随机分布比均匀分布方式下的复合材料的等效热导率大，不同的粒子空间分布结构是影响复合材料热导率的关键因素。