Abstract We report magnetic alignment of single-crystalline microdiamonds with aid of superparamagnetic magnetite in polymeric composites and their material properties. The silicone composite containing aligned microdiamonds shows interesting properties in alignment direction, including enhancement of thermal conductivity, 250% higher than that of randomly dispersed counterpart at a low loading of 5.1 vol%. Composites with aligned diamond exhibited enhanced thermal conductivity and electrical insulation compared with matrix, and are attractive for application as thermal interface materials in the semiconductor industry, though the introduction of magnetite had part of negative effect on electrical resistivity of composites. A two-level model that accounts first-order interaction between particles to calculate effective thermal conductivity of composites with aligned microdiamonds, is found to fit accurately absolute value and tendency of thermal conductivity for composites with aligned particles. Utilizing the modelling procedure, the volume fraction of microdiamonds within chains is 0.3, which is smaller than 0.698 predicted for ideal body-centered-tetragonal arrangement of particles. This suggested that thermal conductivity of composites can be enhanced further by improving microstructures within particle chains.

中文翻译：

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使用涂有超顺磁性磁铁矿的排列金刚石增强聚合物复合材料的热导率

摘要 我们报告了在聚合物复合材料中借助超顺磁性磁铁矿的单晶微金刚石的磁性排列及其材料特性。含有排列的微金刚石的有机硅复合材料在排列方向上显示出有趣的特性，包括导热性的提高，在 5.1 vol% 的低负载下比随机分散的对应物高 250%。尽管磁铁矿的引入对复合材料的电阻率有部分负面影响，但与基体相比，具有排列金刚石的复合材料表现出增强的导热性和电绝缘性，并且对于作为半导体工业中的热界面材料具有吸引力。发现了一个两级模型，该模型考虑了颗粒之间的一阶相互作用，以计算具有对齐微金刚石的复合材料的有效热导率，该模型可以准确拟合具有对齐颗粒的复合材料的热导率的绝对值和趋势。利用建模程序，链内微金刚石的体积分数为 0.3，小于理想体心四边形颗粒排列预测的 0.698。这表明通过改善颗粒链内的微观结构可以进一步提高复合材料的热导率。小于 0.698 预测的理想体心四边形粒子排列。这表明通过改善颗粒链内的微观结构可以进一步提高复合材料的热导率。小于 0.698 预测的理想体心四边形粒子排列。这表明通过改善颗粒链内的微观结构可以进一步提高复合材料的热导率。