界面电流介入时石墨烯的载流摩擦行为  

Current-carrying friction behavior of graphene with intervention of interfacial current

作　　者：王延庆 李佳豪 彭勇[2] 赵又红[3] 白利春 Wang Yan-Qing;Li Jia-Hao;Peng Yong;Zhao You-Hong;Bai Li-Chun(CRRC Qingdao Sifang CO.,LTD.,Qingdao 266111,China;Key Laboratory of Traffic Safety on Track of Ministry of Education,School of Traffic&Transportation Engineering,Central South University,Changsha 410075,China;School of Mechanical Engineering,Xiangtan University,Xiangtan 411105,China)

机构地区：[1]中车青岛四方机车车辆股份有限公司,青岛266111 [2]中南大学交通运输工程学院,轨道交通安全教育部重点实验室,长沙410075 [3]湘潭大学机械工程学院,湘潭411105

出　　处：《物理学报》2021年第20期232-239,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2016YFB1200505);湘潭大学复杂轨迹加工工艺及装备教育部工程研究中心(批准号:FZGJ2020-009)资助的课题。

摘　　要：采用分子动力学方法建立单晶硅针尖与石墨烯相对滑移的分子模型,研究界面电流对石墨烯摩擦性能的影响.研究结果表明:当施加偏压时,针尖所受的摩擦力比无偏压时增大一个数量级;载流摩擦力随偏压的增大而增大,但不同偏压方向的增幅速率却不一致;不同的法向载荷和基底支撑刚度下石墨烯均呈现出较为稳定的载流摩擦行为,其相似的摩擦力-电压关系验证了载流影响的稳定性.电流引入后摩擦力的上升可归因于载流区域的扩大,导致库伦相互作用在摩擦界面处的吸附能中占据主要地位.基于Prandtl-Tomlinson模型系统讨论了石墨烯的载流摩擦机理,认为该机理与石墨烯的褶皱效应相违背,而遵循能量势垒理论体系.Graphene has shown the great potential applications in the field of solid lubricants due to its outstanding mechanical properties and chemical inertness.The introduction of interfacial current at the graphene-lubricated surface is expected to tune the lubrication performance of graphene.Here in this work,an atomistic configuration of single-crystal silicon tip sliding against graphene supported by an elastic substrate is constructed to investigate the current-carrying friction behavior of graphene by using molecular dynamics simulations.The effects of applied voltages,normal loads and substrate stiffnesses on the current-carrying friction behavior of graphene are systematically explored.The simulation results show that when the bias voltage is applied to the graphene-based system,the friction force undertaken by the tip is one order of magnitude larger than when applying no bias voltage.The friction increases with the magnitude of bias voltage increasing,but the increasing rate varies in different directions of bias voltage.A similar friction-voltage relationship of graphene under different normal loads and substrate stiffnesses indicates its relatively stable current-carrying friction behavior and the robust current-carrying effect.The increased friction force of graphene after the introduction of interfacial current can be attributed to the expansion of current-carrying region,causing Coulomb interactions instead of van der Waals interactions to dominate the adhesions at the friction interface.Based on the Prandtl-Tomlinson model,the current-carrying friction mechanism of graphene is systematically discussed.It is found that such a friction mechanism is different from the pucker effect of graphene,but follows the energy barrier theory.This work promotes the graphene to be used as the typical solid lubricant under the complex operation conditions with the voltage-induced current going through friction interfaces.

关 键 词：石墨烯 载流摩擦 能量势垒 分子动力学 

分 类 号：TQ127.11[化学工程—无机化工]