等离子体刻蚀对石墨烯纳晶碳膜的加工机理及摩擦学行为调控研究

Graphene exhibits great potential application in the field of superlubricity design due to the extremely low shear strength between graphene layers. However, in the macroscopic application, the weak van der Waals interaction between graphene layers would simultaneously cause problem such as weak mechanical strength and short wear life. In order to broaden the large-area macroscopic application of graphene superlubricity property, it is essential to extend the film wear life under the condition of maintaining the ultra-low friction. This proposal provides a plasma etching method to regulate the atomic structure and surface topography of the graphene-based carbon film, and will carry out researches on the plasma etching mechanism and the effect of top-surface restructuring and micro-/nano-texturing on the frictional behavior of the graphene nanocrystallites embedded carbon film. The manufacturing mechanism of plasma etching on carbon nano-surface will be clarified. The etching induced top-surface restructuring makes the film surface densification and introduces functional groups into the top layer, and their tuning mechanism on the wear life and friction coefficient will be elucidated. After constructing the surface micro-/nano-texture, the influence of the wear debris transfer behavior on the tribological properties of the carbon film will be revealed. Finally a graphene-based carbon film with ultra-low friction coefficient and long wear life will be fabricated. The research outcomes have scientific significance for clarifying the anti-friction and wear-resistance mechanism of the graphene-based carbon film, and have important engineering application value for guiding the design of the graphene superlubricity system under macroscopic scale.

石墨烯由于层间极低的剪切强度在超滑系统设计领域展现出巨大潜力，但在宏观应用中层间较弱的范德华力也会造成薄膜机械强度低、磨损寿命短等问题。如何在保留超低摩擦特性的前提下提高石墨烯基薄膜的磨损寿命成为石墨烯超滑特性走向大面积宏观应用的关键。本项目提出采用等离子体刻蚀技术对石墨烯基薄膜进行原子结构调控和表面形貌设计，围绕等离子体刻蚀加工机理，以及表层结构重组和表面微纳织构加工对石墨烯纳晶碳膜摩擦学行为的影响机制展开研究。项目旨在阐明刻蚀加工过程中等离子体与碳纳米表面的反应原理，分析刻蚀重构诱导的表层致密化及官能团修饰对碳膜磨损寿命及摩擦系数的调控机制，并揭示微纳织构构筑下摩擦界面磨屑转移行为对碳膜摩擦学性能的影响规律，最终获得兼具超低摩擦系数和长磨损寿命的石墨烯基薄膜。研究成果对于揭示石墨烯基薄膜的减摩耐磨机制具有重要的科学意义，对于指导宏观尺度下石墨烯的超滑系统设计具有重要的工程应用价值。

石墨烯由于层间极低的剪切强度在超滑系统设计领域展现出巨大潜力，但在宏观应用中层间较弱的范德华力也会造成薄膜机械强度低、磨损寿命短等问题。如何在保留超低摩擦特性的前提下提高石墨烯基薄膜的磨损寿命成为石墨烯超滑特性走向大面积宏观应用的关键。本项目提出采用等离子体刻蚀技术对石墨烯基薄膜进行原子结构调控和表面形貌设计，围绕等离子体刻蚀加工机理，以及表层结构重组和表面织构加工对石墨烯纳晶碳膜摩擦学行为的影响机制展开研究。（1）基于电子回旋共振纳米表面加工系统，实现了氩、氧、氟等离子体刻蚀加工工艺。利用氩、氧、氟等离子体分别刻蚀已沉积的石墨烯纳晶碳膜，分析了刻蚀加工对碳膜刻蚀速率、表面粗糙度、刻蚀重构深度、表层sp3键含量以及官能团引入的影响，阐明了氩、氧、氟等离子体刻蚀加工石墨烯纳晶碳膜过程中表层原子去除及结构重组机理；（2）采用重复沉积-刻蚀过程制备了与初始石墨烯纳晶碳膜同等膜厚的等离子体刻蚀重构碳膜，通过纳米压痕和纳米划痕测试对比，探明了离子注入诱导的表层致密化对碳膜机械性能的增强作用。通过对比石墨烯纳晶碳膜与氧等离子体刻蚀重构碳膜的摩擦磨损曲线，揭示了刻蚀重构层机械性能增强和重构碳膜表面粗糙度降低对碳膜磨损寿命的改善机理。进一步采用氟等离子体刻蚀加工在碳膜表面引入氟原子，对表面的碳悬键进行钝化以降低碳膜的表面能，最终使碳膜的摩擦系数从0.17降低0.04；（3）利用等离子体刻蚀技术结合掩模工艺构筑了具有不同孔径和深度的织构化碳膜，测试了织构化碳膜在干摩擦状态下的摩擦磨损曲线，结合对磨球表面转移膜的纳米结构表征，发现了表面织构的构筑有利于对磨表面大面积石墨烯转移膜的形成，从而有效降低了摩擦系数并极大提高碳膜的磨损寿命。研究成果对于揭示石墨烯基薄膜的减摩耐磨机制具有重要的科学意义，对于指导宏观尺度下石墨烯的超滑系统设计具有重要的工程应用价值。