石墨烯摩擦自定序效应及其与宏观真空超低摩擦特性的关系规律

A joint conductive and lubricating material has important application prospects and urgent needs in the field of national aerospace engineering. Our group recently discovered that two-dimensional nano-structured graphene can break through the defects of graphite, showing a special friction induced self-orienting effect and super-low friction characteristic at macro-scale in vacuum environment. Combined with its high conductivity, graphene has great potential. This project intends to carry out the study on friction induced self-orienting effect and its relationship with macro-scaled ultra-low friction of graphene in vacuum environment. Considering the microcosmic and macroscopic structural factors, the effects of self-orienting, the incommensurate structure, the structural deformation, and chemical interactions are studied by the design of the structural features, including the number of layers, size, commensurate degree, functional groups and substrate, at different stages during the dynamic sliding process. Combined with the experimental and theoretical simulation results, the key structural factors are clarified, and the self-orienting mechanism, relationship between self-orienting structure and vacuum tribological properties of graphene and macroscopic friction mechanism of graphene are revealed. On the above basis, new graphene coating materials with conductive and lubricating integrated performance are developed. This research will improve the level of understanding of the lubrication failure mechanism of graphite in vacuum and the nature of the low friction for layered structure materials, and have important theoretical value and guiding significance to further design new space conductive lubricating material, and explore the practical application of graphene lubricants in space fields to meet the urgent application requirements.

国家航天重大装备发展对导电与真空润滑一体化材料提出了迫切需求。申请者前期研究发现高传导的石墨烯在宏观真空摩擦过程中表现出独特的摩擦自定序效应和超低摩擦特性，克服了石墨真空润滑失效的性能缺陷，极具潜力。本项目拟深入开展其摩擦自定序机制及其与真空摩擦性能关系规律的研究。综合考虑微观和宏观结构因素，结合实验和理论模拟，研究石墨烯结构特征对摩擦自定序行为的影响规律，揭示石墨烯二维结构摩擦自定序机制；研究宏观摩擦动态过程中自定序效应、非公度结构效应、结构形变效应、化学键作用在不同阶段的影响，揭示石墨烯定序结构和真空润滑性能的关系规律和宏观动态摩擦机理本质。在此基础上，指导发展具有导电与润滑一体化性能的新型石墨烯涂层材料。通过研究，可以突破传统石墨真空摩擦磨损失效机制，认识层状结构材料低摩擦科学本质，建立二维材料摩擦新理论；同时可以为新型空间导电润滑材料的设计提供支持，具有重要的理论意义和应用价值。

本项目结合超滑研究前沿与国家航天重大装备发展对导电与真空润滑一体化材料的迫切需求，聚力于导电性极佳的石墨烯二维材料摩擦自定序润滑效应及宏观超滑性能的实现。系统考察了石墨烯在摩擦定序前后阶段，尺寸、官能团、缺陷等内在结构因素以及湿度、气氛、载荷等外在环境因素对其摩擦学行为的影响，建立了构效对应关系，揭示了石墨烯基二维材料在宏观接触条件下的润滑与动态失效机制，层-层滑移的润滑机制发挥主要作用，定序层状摩擦界面结构的形成和维持是决定其长效低摩擦性能的关键；发现了共价/离子型和离子/离子型二维异质材料的超滑新现象，从原子成键形式和空间构型的角度揭示了超滑界面化学物理作用机理，建立了固体超滑二维异质结构设计原则和方法，阐明了摩擦学“协同润滑”现象背后的科学本质；在此基础上，提出了“微纳点超滑”组合“宏观面超滑”表/界面宏观超滑设计新原理，建立了表面织构、预磨合定序、离子/共价异质复合一系列设计新方法，首次报道实现了宏观接触尺度、工程基材表面鲁棒性固体结构超滑，受到了国内外同行的广泛关注。清华大学雒建斌院士在最新综述文章（Nano Energy, 2021, 106092）中摘选为：固体超滑研究的代表工作进展；进一步结合航天领域载流摩擦润滑的技术难题，发展出了具有导电与润滑一体化的新型石墨烯空间润滑复合涂层材料与技术，实现了在保持接触高电导性的基础上，摩擦系数、寿命等关键性能指标较现役金电镀膜层改善数倍以上。目前已完成实际滑环零件（信号盘和功率盘）的制备，择机应用考评，为石墨烯润滑材料在航天领域的应用提供了基础数据与理论支持。本项目在以Advanced Materials、Advanced Functional Materials为代表的材料领域学术顶级期刊发表论文24篇，其中SCI收录20篇（一区期刊6篇，2篇IF﹥10），EI收录4篇，中文核心4篇；出版专著1部；申报发明专利8项（授权8项）；获得甘肃省技术发明一等奖1项；获得航天科技集团科学技术发明奖1项；培养硕/博研究生6名。