金刚石复合材料有序微纳结构界面构筑及其高导热机制

Diamond composite is a new thermal management material with the most application prospect, but due to the interfacial selective reaction and interfacial thermal resistance, their high thermal conductivity is severely limited. Micro/nano-structures endow material with disparate physical and chemical properties, and they have an enormous potential in constructing interface for high performance composites. Therefore, a new research is proposed in this project. Namely, with the constructing ordered micro/nano-structures on diamond surface, eliminate the selectivity of interfacial reaction by aligning the surface free energy, and reduce the interfacial thermal resistance of diamond composite by enhancing the transmissivity of phonon at the interface. The influence of phase structure transformation, surface functional groups and micro/nano morphologies on controlling the surface free energy will be researched systematically to reveal the regulatory mechanism of ion beam bombardment on aligning the surface energy. Master the effect of diamond surface micro/nano-structures on adjusting the interfacial reaction, and illustrate the principle of overcoming the selective interfacial reaction by the constructed surface structures. Meanwhile, regulate the interfacial microstructure for further enhancing the property of the composite. The structure-property relationships of the ordered micro/nano-structured interface will be established to clarify the mechanism of the higher interfacial thermal conductance in the diamond composites. The project plays a significant exemplary role in improving the thermal property of composite by constructing micro/nano-structured interface, and provides a new research idea for optimizing composites performance through interface design.

金刚石复合材料是最具应用前景的新型热管理材料，然而选择性界面反应及界面热阻却限制了其高导热性能的实现。微纳结构赋予材料丰富的理化内涵，在高性能复合材料界面构筑方面具有巨大潜力。为此，本项目提出通过金刚石表面有序微纳结构构建，诱导各取向表面能趋同、消除界面反应选择性，提高复合材料界面处声子透过率、降低界面热阻的研究方案。系统研究离子束作用下金刚石各取向表面相结构转变、官能团调整、微纳形貌变化对表面能的影响，揭示各取向表面能趋同的离子束非平衡态调控机理；研究金刚石表面微纳结构构筑对其复合材料界面反应行为的影响，阐明克服金刚石复合材料选择性界面反应问题的机制；调控复合材料界面结构，提升复合材料导热性能，建立金刚石复合材料有序微纳结构界面构性关系，揭示有序微纳结构界面高导热机制。项目在利用界面微纳结构提升复合材料导热性能方面起到了重要示范作用，为优化复合材料性能提供了界面设计的新思路。

金刚石/铜复合材料具有超高的理论热导率及可调的热膨胀系数，是满足功率半导体、5G射频通讯、有源相控阵雷达等高功率器件高效散热需求的理想材料。克服金刚石-金属选择性界面粘接问题、同时降低界面热阻是获得优异导热性能的关键。本项目利用离子束非平衡态加工特性，梳理了离子束轰击作用下金刚石浅表区域波纹微纳结构形成规律，研究了表面相结构转变、官能团调整对各取向反应活性的影响，实现了金刚石单晶颗粒各取向表面sp3/sp2碳结构含量趋同，阐明了金刚石各取向表面反应活性趋同的离子束非平衡态调控机制；与此同时，选取钨为金刚石/铜界面改性元素，采用磁控溅射方法对离子束预处理的金刚石进行金属化，并通过熔渗方法制备了金刚石/铜复合材料，系统研究了金刚石表面钨改性层在热处理过程中的碳化现象，建立了复合材料界面精细结构与热传导性能间对应关系，揭示了通过调控界面层物相结构、厚度提升复合材料导热性能的内禀机制，阐明了离子束轰击处理对金刚石/铜界面热导的影响规律及增益机理。本项目所研制的金刚石铜复合材料热导率高达943 W/m·K，为离子束构筑导热增强体表面微纳结构、调控复合材料界面反应、优化材料综合性能提供典型范例，拓宽了导热复合材料界面构筑及性能优化研究思路。本项目发表论文6篇，授权/申请国家发明专利2项，培养研究生5名。