无压浸渗高导热鳞片石墨/铝复合材料微结构导热通路构建及其导热机制研究

Heat dissipation has become the key to improve the performance of devices and systems in the electronic industry. As a highly efficient thermal transport material, graphite flakes/aluminum composites has become one of the research hotspot in the field of thermal management, however, there is no report on the graphite flakes/aluminum composites prepared by pressless infiltration. This project focuses on the bottleneck problem of the pressless infiltration technology and the key scientific problems that restrict the complex effect of materials. On the basis of the existing pressure infiltration research experience, the pressless infiltration controllable preparation technology of graphite flakes/aluminum composites with high thermal conductivity and low expansion is broke through the optimization of matrix alloy composition and the regulation of interfacial microstructure. Through the regulation of reinforcements spatial distribution, the designation of the composite configuration is realized and the mechanisms of the microstructural heat conductive paths of high performance graphite flakes/aluminum composites are described. Combined with the formation and evolution mechanism of the interface under multiple factors, the relationship among the spatial distribution of reinforcements, the interfacial microstructure and the thermo-physical properties is established, and thermal transport mechanism of composites are revealed. This project will provide the technical support and theoretical basis for graphite flakes/aluminum composites preparation and performance designation.

散热问题已成为电子工业中不断提高器件和系统性能的关键。鳞片石墨/铝复合材料作为高效热输运材料而成为热管理领域的研究热点，而无压浸渗技术制备该材料尚无报道。本项目围绕无压浸渗制备技术的瓶颈问题和制约材料复合效应发挥的关键科学问题，在作者已有的压力浸渗研究基础上，通过基体合金成分设计和界面微区调控，突破高导热、低膨胀鳞片石墨/铝复合材料无压浸渗的高品质可控制备技术。调控增强相空间分布，实现复合构型设计，阐明高性能鳞片石墨/铝复合材料微结构导热通路的实现和作用机制。结合多因素作用下复合材料界面的形成与演变规律，建立增强相空间分布、界面微区结构与导热性能的耦合响应规律，揭示复合材料的热传输行为和导热机制。通过深入系统的研究，为高品质鳞片石墨/铝复合材料的复合制备与性能导向设计提供技术支撑和理论依据。

本项目围绕无压浸渗技术制备定向高导热鳞片石墨/铝复合材料的关键问题，理论分析了不同基体合金体系的热力学参数，增强相与基体合金的界面反应和润湿行为，Mg和Si可作为有利的基体合金化元素，Mg元素含量的变化范围为(3~9)%，Si元素含量的变化范围为(6~18)%。成功制备了不同鳞片石墨/Al-Mg-Si复合材料，鳞片石墨在基体中的取向分布随着石墨片尺寸的增加而改善，复合材料中的主要物相为Al、C、Al4C3、Mg2Si和Si。鳞片石墨均匀分布在复合材料基体中，其与铝基体界面结合良好，沿着石墨和铝的界面处分布着一层明显的界面层，较高的浸渗温度使得石墨片和铝在高温下生成了Al4C3界面反应产物。界面处非晶层中分布着大量的纳米晶，非晶层中O元素的含量较高，并且含有少量的C和N元素。基于界面热传导模型分析了合金元素对界面热导和复合材料热导率的影响，严重的界面反应使得实际制备工艺获得的复合材料导热性能远低于预期，增强相表面改性是控制界面反应改善导热性能的关键，Si、SiC和WC是比较理想的镀层材料。