School of Science, Xi'an Polytechnic University, Xi'an 710048, China.
Nanoscale. 2018 Feb 1;10(5):2447-2453. doi: 10.1039/c7nr07839k.
Nanoscale friction is generally found to be a function of the contact area. However, little is known whether and how it is dependent on the contact area shape. In this study, based on molecular dynamics (MD) simulations about a rectangular graphene flake sliding on a diamond-supported graphene substrate, we show that the friction between the flake and the substrate is significantly dependent on the flake edge oriented perpendicular to the sliding direction, but less dependent on the edge along the sliding direction. As a result, the friction between the flake and the substrate is closely related to the aspect ratio of the flake. We propose a novel nanoscale friction formula for the translational motion of a rectangular slider. The simulation data fit the formula well and the effect of the aspect ratio on nanoscale friction can thus be efficiently captured. We discuss also the origin of the edge orientation dependent nanoscale friction. The present findings provide not only a preliminary evaluation of the contact area shape dependent nanoscale friction, but also a quite important guide for modeling the friction properties of nanodevices based on two-dimensional (2D) materials.
纳米尺度摩擦通常被认为是接触面积的函数。然而，对于它是否以及如何依赖于接触面积的形状，人们知之甚少。在这项研究中，基于关于在金刚石支撑的石墨烯衬底上滑动的矩形石墨烯薄片的分子动力学 (MD) 模拟，我们表明薄片与衬底之间的摩擦显著依赖于垂直于滑动方向的薄片边缘取向，而对沿滑动方向的边缘依赖性较小。因此，薄片和衬底之间的摩擦与薄片的纵横比密切相关。我们提出了一个用于矩形滑块平移运动的新型纳米尺度摩擦公式。模拟数据很好地符合该公式，因此可以有效地捕捉纵横比对纳米尺度摩擦的影响。我们还讨论了边缘取向依赖性纳米尺度摩擦的起源。目前的研究结果不仅提供了对接触面积形状依赖性纳米尺度摩擦的初步评估，而且为基于二维 (2D) 材料的纳米器件摩擦特性建模提供了非常重要的指导。
