The anomalous effect of electric field on friction for microscale structural superlubric graphite/Au contact  

作　　者：Yelingyi Wang Jin Wang Tielin Wu Weipeng Chen Deli Peng Zhanghui Wu Ming Ma Quanshui Zheng 

机构地区：[1]Center for Nano and Micro Mechanics,School of Aerospace Engineering,Tsinghua University,Beijing 100084,China [2]Department of Engineering Mechanics,School of Aerospace Engineering,Tsinghua University,Beijing 100084,China [3]International School for Advanced Studies(SISSA),Trieste 34136,Italy [4]International Centre for Theoretical Physics(ICTP),Trieste 34151,Italy [5]Institute of Superlubricity Technology,Research Institute of Tsinghua University in Shenzhen,Shenzhen 518057,China [6]Department of Mechanical Engineering,State Key Lab of Tribology in Advanced Equipment(SKLT),Tsinghua University,Beijing 10084,China [7]Institute of Materials Research,Tsinghua Shenzhen International Graduate School,Shenzhen 518057,China

出　　处：《National Science Review》2024年第9期265-272,共8页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China(11572173,51961145304,11921002,11890671,11890673 and 12204321);China Postdoctoral Science Foundation(BX20220181);Shenzhen Fundamental Research Key Project(JCYJ20200109150608043),and ERC ULTRADISS(834405).

摘　　要：The current-carrying friction characteristics are crucial for the performance of a sliding electrical contact,which plays critical roles in numerous electrical machines and devices.However,these characteristics are influenced by multiple factors such as material surface quality,chemical reactions,and atmospheric environment,leading to a challenge for researchers to comprehensively consider these impacts.Structural superlubricity(SSL),a state of nearly zero friction and no wear between contact solid surfaces,provides an ideal experimental system for these studies.Here,with microscale graphite flakes on atomic-flattened Au surface under applied voltages,we observed two opposite friction phenomena,depending only on whether the edge of graphite flake was in contact with the Au substrate.When in contact the friction force would increase with an increasing voltage,otherwise,the friction force would decrease.Notably,when the voltage was turned off,the friction force quickly recovered to its original level,indicating the absence of wear.Through atmosphere control and molecular dynamics simulations,we revealed the mechanism to be the different roles played by the water molecules confined at the interface or adsorbed near the edges.Our experimental results demonstrate the remarkable tunable and robust frictional properties of SSL under an electrical field,providing an ideal system for the fundamental research of not only sliding electrical contacts,but also novel devices which demand tunable frictions.

关 键 词：current-carrying friction structural superlubricity water sliding electrical contact 

分 类 号：TH117[机械工程—机械设计及理论]