The Role of Intermediate States in Low-Velocity Friction between Amorphous Surfaces

TL;DR

This study uses accelerated molecular dynamics to explore how intermediate states influence low-velocity friction between amorphous surfaces, revealing their role in velocity plateaus and aligning simulations with experimental data.

Contribution

It introduces a new understanding of the role of intermediate states in amorphous friction, supported by simulations and a simple theoretical model.

Findings

Intermediate states arise in amorphous friction under force.

Emergence of velocity plateaus at low speeds and high temperatures.

Theoretical model successfully explains experimental and simulation results.

Abstract

Simulated sliding between an oxidized silicon tip and surface over six decades of velocity using accelerated molecular dynamics reproduces the experimentally observed velocity dependence of the friction force. Unlike in the crystalline case, as increasing force is applied to the amorphous tip intermediate states arise. These intermediate states serve as critical transition pathways. The emergence of such states leads to the emergence of a plateau in sliding velocity at lower sliding speeds and higher temperatures. A simple theory based on these observations successfully describes both the experimental and the simulated data.