Atomistic modelling of friction of Cu and Au nanoparticles adsorbed on graphene

Abstract

We present classical molecular dynamics calculations of the behavior of copper and gold nanoparticles on a graphene sheet, sheared with a constant applied force F a . The force F s acting on the particle from the substrate depends on the material of the nanoparticles (Au or Cu), and exhibits a sawtooth dependency on time, which we attribute to local commensurability between the metal nanoparticle surface atomic positions with the graphene lattice. The time-averaged value of F s (the friction force) acting on Au nanoparticles increases linearly with the contact area, having slopes close to the experimentally observable ones. A qualitative model is proposed to explain the observed results.

Atomistic modeling of tribological properties of Pd and Al nanoparticles on a graphene surface

“…The contact area in [ 10 – 11 ] is determined, as in experiments, on the basis of the lateral sizes L x and L y of the nanoparticle, approximating it with an ellipse. However, for particles where the internal bonding potential between the atoms is much stronger than the bonding potential to the substrate ( ), this approach may result in a “contact area” that is much bigger than the area obtained by only including those atoms that interact strongly with the substrate.…”

“…Therefore, computer modeling, in particular molecular dynamics (MD), is a useful tool for the theoretical study of friction and wear at the atomic level [ 2 , 8 , 10 , 12 , 15 – 19 ]. Preliminarily MD studies were carried out for the formation and friction of Ag, Ni, Au, Cu nanoparticles on graphene [ 10 – 11 ]. This paper extends the study to Al and Pd nanoparticles [ 17 ].…”

“…Although MD simulations of friction at the atomic level have provided some understanding of interfacial processes, they are limited to much shorter spatial and temporal length scales than in most experiments. Recent experimental and computer simulation studies of static and sliding friction of metallic nanoparticles have focused on the dependence of friction on the particle size, morphology and orientation [ 10 – 11 13 – 14 17 ].…”

“…It is designed to model alloys and is fully expressed through analytical functions, unlike the first versions of the embedded atom method, where cubic splines were used for the embedding function. The in-plane forces in graphene are described by a spring potential, and the interactions between the nanoparticle and the graphene carbon atoms are taken as a Lennard-Jones potential, which was chosen the same for the Al and Pd atoms [ 10 – 11 ].…”

Universal Aging Mechanism for Static and Sliding Friction of Metallic Nanoparticles

“…At this point the question about the physical origin for the observed contact aging of the nanoparticle-graphite interface still remains. Molecular dynamics simulations for Au and Ag nanoparticles on HOPG have indicated atomic relaxations at the particle-substrate interface that are time dependent [41]. These relaxations resulted in the formation of commensurate patches at the nanoparticle-substrate interface.…”