Influences of out-of-plane elastic energy and thermal effects on friction between graphene layers

Yun Dong,Zongxiao Zhu,Tianjing He,Fuqiang Wang

doi:10.1063/1.5083883

Abstract

Through molecular dynamic simulations, a system for investigating the contributions of elastic deformation energy and thermal activation effects to friction has been constructed. In this system, a graphene flake slides on a suspended graphene layer anchored on a bed of springs. The “graphene–spring” system provides a useful ideal approach to model different layers of graphene through changing the stiffness of the springs. The results first indicate that both the friction force and the elastic deformation energy have an exponential dependence on the support stiffness. Second, the observed non-monotonic variation in friction manifested by peaks and plateaus with increasing temperature results from the changing rate of energy dissipation due to the transition of slip regimes. Therefore, we suggest that the friction force emanates from the competition between the interfacial energy barrier and out-of-plane elastic deformation energy, as well as the competition between the thermal activation effects and transition of slip regimes. Therefore, the observation can extend the validity of the Prandtl–Tomlinson model on friction phenomena. Our simulations are intended to provide theoretical guidance when considering the influence of stiffness on the friction between graphene layers in the design of nanodevices.

Highlights

The energy dissipation mechanism caused by friction is still not fully understood to date, owing to the complex phenomena occurring at the buried interface of sliding surfaces.1–3 The Prandtl– Tomlinson (PT) model and its extensions4–6 have been widely applied to help better understand the mechanism of friction
A system with a graphene flake sliding on a suspended graphene layer anchored on a bed of springs is constructed based on molecular dynamics (MD) simulations
The results indicate that both friction force and elastic deformation energy exhibit an exponential dependence on the support stiffness

Summary

Introduction

The energy dissipation mechanism caused by friction is still not fully understood to date, owing to the complex phenomena occurring at the buried interface of sliding surfaces. The Prandtl– Tomlinson (PT) model and its extensions have been widely applied to help better understand the mechanism of friction. Based on the original PT model, when the substrate is rigid, the variations in the corrugation potential of the buried interface and the friction force have the same tendency. This considered friction as a non-adiabatic phenomenon. Graphene is regarded as an ideal material for investigating the characteristic of atomic-scale friction because its structure has a high specific surface area to volume ratio.. Graphene is regarded as an ideal material for investigating the characteristic of atomic-scale friction because its structure has a high specific surface area to volume ratio.5,8 In this regard, understanding the fundamental physics of friction on graphene is of particular importance. Graphene is regarded as an ideal material for investigating the characteristic of atomic-scale friction because its structure has a high specific surface area to volume ratio. In this regard, understanding the fundamental physics of friction on graphene is of particular importance.

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Results

Conclusion