Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation.

Ruiting Tong,Zefen Quan,Bin Han,Geng Liu,Yangdong Zhao

doi:10.3390/nano9111617

Abstract

In nanomaterials, the surface or the subsurface structures influence the friction behaviors greatly. In this work, nanoscale friction behaviors between a rigid cylinder tip and a single crystal copper substrate are studied by molecular dynamics simulation. Nanoscale textured surfaces are modeled on the surface of the substrate to represent the surface structures, and the spacings between textures are seen as defects on the surface. Nano-defects are prepared at the subsurface of the substrate. The effects of depth, orientation, width and shape of textured surfaces on the average friction forces are investigated, and the influence of subsurface defects in the substrate is also studied. Compared with the smooth surface, textured surfaces can improve friction behaviors effectively. The textured surfaces with a greater depth or smaller width lead to lower friction forces. The surface with 45° texture orientation produces the lowest average friction force among all the orientations. The influence of the shape is slight, and the v-shape shows a lower average friction force. Besides, the subsurface defects in the substrate make the sliding process unstable and the influence of subsurface defects on friction forces is sensitive to their positions.

Highlights

With the development of micro/nano electromechanical systems [1], the sizes of components come to a micro/nanoscale, and the molecular forces between the contact bodies play an important role
When the depth is greater than 3.615 nm, the average friction forces decrease with the increase in depth, and the average friction forces gradually approach that of the perfect substrate, which means that the effects of subsurface defects on friction become slight when
Using an embedded-atom method (EAM) potential, molecular dynamics (MD) simulations have been carried out to study the effects of FCC copper textured surfaces with different depths, widths, orientations and shapes on friction behaviors during nanoscale sliding contacts

Summary

Introduction

With the development of micro/nano electromechanical systems [1], the sizes of components come to a micro/nanoscale, and the molecular forces between the contact bodies play an important role. Many experiments were performed to investigate the friction properties of nano-textured surfaces. The surface with a lower texture density reduced the grinding forces and average COFs effectively, while the influence of texture orientation was slight, due to a high cutting depth.

Results

Conclusion