Dependence of boundary lubrication on the misfit angle between the sliding surfaces

TL;DR

This study uses molecular dynamics simulations to explore how the misfit angle between sliding surfaces influences boundary lubrication, revealing different sliding regimes and static friction thresholds.

Contribution

It introduces a detailed molecular dynamics model incorporating coordinate- and velocity-dependent damping to analyze boundary lubrication behavior.

Findings

Frictional properties depend on the misfit angle between surfaces.

Two sliding regimes, LS and LoLS, are identified and characterized.

Distribution of static friction thresholds varies with surface misfit.

Abstract

Using molecular dynamics based on Langevin equations with a coordinate- and velocity-dependent damping coefficient, we study the frictional properties of a thin layer of "soft" lubricant (where the interaction within the lubricant is weaker than the lubricant-substrate interaction) confined between two solids. At low driving velocities the system demonstrates stick-slip motion. The lubricant may or may not be melted during sliding, thus exhibiting either the "liquid sliding" (LS) or the "layer over layer sliding" (LoLS) regimes. The LoLS regime mainly operates at low sliding velocities. We investigate the dependence of friction properties on the misfit angle between the sliding surfaces and calculate the distribution of static frictional thresholds for a contact of polycrystalline surfaces.