超滑碳膜界面润滑层的原子分辨率结构解析

Amorphous carbon films, which have been confirmed to possess the capacity of superlubricity, are strongly promising for applications as engineering lubricants. However, the relevant mechanisms remain unclear. By establishing different environments and interfacial contact conditions, the underlying superlubricity mechanisms of two hydrogenated carbon films including a-C:H and a-C:H:Si are thoroughly investigated. The superlubricity interfaces are characterized in-situ or quasi-in-situ using the state-of-the-art STEM and EELS to achieve microstructural and compositional information with ultra-high spatial resolving and atomic-scale resolution, aiming to explore the mechanisms of occurrence and existence of superlubricity phenomena. For a-C:H films, the spatial configurations and orientations of interfacial atoms under superlubricity state, mechanisms of formation of transfer layers in-situ and the critical role of hydrogen in surface passivation and friction near-vanishing are revealed. For a-C:H:Si films, the interfacial friction-reducing mechanisms governed by Si-induced tribo-polymerization, principles of formation of nanometer-scale silica lubrication layer in the presence of moisture and lubrication behaviors of water molecules in confined space are clarified. The goal of this project is to provide the most intrinsic structural elucidation for the superlubricity mechanism of carbon films, to enrich the lubrication theory of solid coating lubricates, to provide theoretical and technical support for designing more efficient carbon-based solid lubricants suitable for various service environments.

非晶碳膜已被证实具备超滑特性，作为工程润滑材料具有重大应用前景，但其超滑机制尚不明确。本项目以含氢碳膜a-C:H和a-C:H:Si为两条研究主线，通过对不同测试环境和界面接触条件的精确构建，深入研究其超滑机理。通过采用目前技术水平最高的STEM和EELS对超滑界面进行原位/准原位表征分析，以期获得具有超高空间辨识度和原子分辨率级的微结构和成分信息，摸索超滑的产生条件和存在机理。揭示a-C:H膜在超滑态下界面原子的空间构型和取向规律、转移膜原位形成机制、氢原子在滑移界面钝化和近零摩擦中的核心作用；阐明a-C:H:Si膜在超滑态下基于硅原子诱导的摩擦聚合物化界面减阻机制、大气环境下纳米级硅胶润滑层的成形机制及水分子在受限空间的润滑行为。该项目的实施旨在为碳膜超滑机理的解释提供最本源的结构证据，进一步丰富固体涂层润滑理论，为设计开发满足不同使役条件下持久有效的碳基固体润滑材料提供理论和技术指导。

类金刚石碳膜具备近零摩擦和磨损的超滑特性，作为润滑材料具有重要的科学研究价值和工程应用前景。本项目以含氢超滑碳膜a-C:H和a-C:H:Si为研究对象，发展了一种具有原子分辨率解析能力的FIB-STEM-EELS润滑界面表征方法，基于此技术探索碳膜超滑现象的产生条件和作用机理。阐明了自配对a-C:H碳膜在不同接触应力下超滑态的稳定性以及界面纳米有序结构与超低摩擦阻力的关系；分析了异质界面条件下纳米级转移膜的成形条件与作用机制，重点研究了对偶副材料对转移膜微结构的影响；探讨了Si元素掺杂的自配对a-C:H:Si碳膜的超滑行为，分析了Si元素诱导的界面摩擦聚合物化实现超滑态的作用机制，讨论了摩擦界面重构效应和类聚合物态转移膜在获得超低摩擦过程中的作用；硅掺杂可有效调控含氢碳膜的环境湿度敏感特性，适当的硅含量（10 at.%）掺入碳氢基质中可屏蔽水分子的侵蚀作用，同时在摩擦界面处形成的纳米级硅胶边界润滑层（SiOx·nH2O）的形成即可维持碳膜鲁棒性的超低摩擦润滑状态；二元低维纳米材料复配润滑剂的协同作用下，摩擦诱导微区纳米润滑单元的自调节可显著增强该多元润滑材料体系的环境适应性和润滑性能的持久性。通过该项目的实施获取了碳膜在多因素界面耦合条件下最本源的超滑机理结构证据，阐明了基于界面纳米结构润滑层尤其是转移膜原位构筑行为的润滑机制，进一步丰富和完善碳基固体润滑剂的润滑理论。