College of Mechanical Engineering, Donghua University, Shanghai 201620, China.
Nanoscale. 2018 Jan 25;10(4):1855-1864. doi: 10.1039/c7nr07517k.
Graphene shows great potential applications as a solid lubricant in micro- and nanoelectromechanical systems (MEMS/NEMS). An atomic-scale friction strengthening effect in a few initial atomic friction periods usually occurred on few-layer graphene. Here, velocity dependent friction strengthening was observed in atomic-scale frictional behavior of graphene by atomic force microscopy (AFM). The degree of the friction strengthening decreases with the increase of velocity first and then reaches a plateau. This could be attributed to the interaction potential between the tip and graphene at high velocity which is weaker than that at low velocity, because the strong tip-graphene contact interface needs a longer time to evolve. The subatomic-scale stick-slip behavior in the conventional stick-slip motion supports the weak interaction between the tip and graphene at high velocity. These findings can provide a deeper understanding of the atomic-scale friction mechanism of graphene and other two-dimensional materials.
石墨烯在微纳机电系统（MEMS/NEMS）中作为固体润滑剂具有很大的应用潜力。在少层石墨烯上，通常在几个初始原子摩擦周期中会出现原子级摩擦强化效应。在这里，原子力显微镜（AFM）观察到了石墨烯原子级摩擦行为中随速度变化的摩擦强化现象。摩擦强化程度随着速度的增加先减小，然后达到一个平台。这可以归因于高速时尖端和石墨烯之间的相互作用势能比低速时弱，因为强的尖端-石墨烯接触界面需要更长的时间来演化。在传统的粘滑运动中，亚原子级的粘滑行为支持高速时尖端和石墨烯之间的弱相互作用。这些发现可以提供对石墨烯和其他二维材料的原子级摩擦机制的更深入理解。
