Frictional anisotropy of metal nanoparticles adsorbed on graphene

TL;DR

This study uses molecular dynamics simulations to reveal that silver and nickel nanoparticles exhibit directional dependence in friction when sliding on graphene, with significant anisotropy and complex force behavior.

Contribution

It demonstrates the existence of frictional anisotropy for metal nanoparticles on graphene and provides a qualitative explanation based on the patch model.

Findings

Frictional anisotropy observed for silver and nickel nanoparticles.

Maximum friction force can be about twice the minimum.

Friction force dependencies vary with sliding direction.

Abstract

Friction force acting on silver and nickel nanoparticles sheared on a graphene sheet in different lateral directions is investigated using classical molecular dynamics simulations. The results reveal the existence of frictional anisotropy for both metals. In most cases, the maximum value of the friction force is about two times larger than the minimum one. The form of dependencies of instantaneous values of the friction force components on the corresponding lateral components of the position of the centre of mass of the nanoislands strongly depends on sliding direction, varying between the sawtooth and the irregular one. A qualitative explanation of the results based on the "patch" model is proposed.