Diamond/Al复合材料钨基纳米多相界面演化机制及其构效关系研究

Formation of the interface with low thermal resistance is the key to improve thermal conductivity and the mechanical performance of the Diamond/Al composites. It has been reported that the W-based interfaces are the optimized interface. However, the modification of the W-based nano-multiphases interface in Diamond/Al composites and the corresponding relationship between microstructure and thermal/mechanical has not been investigated yet. In the present work, it is designed that W- coatings with various thickness would be deposited on the surface of the diamond particles by magnetron sputtering method, and then the diamond particles would react with the W coatings to form the W-based nano-multiphases interface. The microstructure evolution of the W-based nano-multiphases interface under different high temperature reaction process would be investigated, and the effect of the crystal planes and the hybridization of the carbon atoms on the reaction and the corresponding growth mechanism of the interfacial products between diamond and the W coatings would be discussed. Furthermore, the effect of the interface with various thickness, components and the configurations on the thermal conductivity and the mechanical properties of the Diamond/Al composites prepared by the pressure infiltration method would be investigated, and the corresponding relationship between microstructure and thermal/mechanical of the Diamond/Al composites would be established. It would provide experimental and theoretical support for the design and optimization of the interface and the thermal/mechanical performance of the Diamond/Al composites.

形成良好结合的低热阻界面是提高Diamond/Al复合材料导热和力学性能的关键，文献报道W基界面是最好的界面材料，但是Diamond/Al复合材料W基纳米多相界面结构的调控及其与复合材料导热和力学性能的构效关系尚缺少深入研究。本项目以磁控溅射法在金刚石表面沉积不同厚度的W纳米涂层，通过金刚石颗粒与W涂层高温反应形成W基纳米多相界面，研究不同高温反应工艺下W基纳米多相界面的组织演化规律，揭示不同晶面族、不同杂化状态对金刚石碳原子与W的反应和界面相生长机制的影响规律，阐明Diamond/Al复合材料W基纳米多相界面调控机制；研究不同厚度、不同物相成分与构型的界面结构对压力浸渗法制备的Diamond/Al复合材料的导热性能和力学行为的影响规律，建立W基纳米多相界面结构与Diamond/Al复合材料导热和力学性能的构效关系，为高导热铝基复合材料界面和导热/力学性能的设计调控提供实验和理论依据。

目前Diamond/Al复合材料界面结构的调控及其与复合材料构效关系尚缺少深入研究。本项目研究了W基纳米多相界面的组织演化规律及其对复合材料导热行为和力学的影响机制，为高导热铝基复合材料界面和导热/力学性能的设计调控提供实验和理论依据。.镀钨金刚石/铝复合材料中存在金刚石、铝、钨、碳化钨等多种物相。通过对结合能及生成焓的计算，确定了W-C二元相热力学稳定性依次为h-WC＞ε-W2C＞β-W2C＞γ-W2C＞α-W2C＞c-WC。h-WC(001)极性表面中W终端表面能最低，为3.56 J·m-2；ε-W2C (001)极性表面中C终端表面能最低为3.76 J·m-2。对不同位相关系的Diamond/Al界面性质进行了计算，相对于Diamond/Al界面，钨及其碳化物与金刚石之间的界面成键趋势更强，形成的W-C键合强度更高。其中Diamond (100)/W2C(001)是最为稳定、界面结合强度最高的界面结构，其界面间距为1.33 Å，粘附功为10.18 J·m-2。电子结构分析表明，界面处产生的共价/离子混合型的W-C键与C-C非极性共价键在改善界面结合的同时提升了界面处的热传导。利用AMM、DEM模型计算了不同的界面相的理论热导，结果表明W、WC以及W2C相能够提升界面热导，而Al4W、Al5W以及Al12W相则对界面处的热传递不利。.对镀钨金刚石进行高温扩散反应处理，金刚石表面钨涂层在处理过程中要经过表层石墨化，选择性反应、弥散生长、完全转变、选择性开裂几个阶段。在不同涂层的金刚石/铝复合材料界面处观察到了三种界面结构，分别是Al/Diamond直接接触型界面、Al/Al5W/Al/Diamond 反应型界面以及Al/WxC/Diamond过渡型界面。由于占主导地位的Al/WxC/Diamond过渡型界面良好的结合强度以及较低的界面热阻，900°C下处理4h的镀钨金刚石/铝复合材料达到了最佳热性能及力学性能，热导率最高为660W·m-1·K-1，抗弯强度为354 MPa。同时其拥有最佳的稳定性，在200次的冷热冲击过程后，热导率下降幅度最低，为3.89%。.共发表学术论文18篇(封面图片论文1篇)；授权发明专利6项；参加了4次国内外会议；共培养2名博士、3名硕士、3名学士。研究成果已正式应用于高分7号和11号卫星海量数据处理系统，解决了散热难题。