Stick-Slip Mode of Boundary Friction as the First-Order Phase Transition

TL;DR

This paper models boundary friction as a first-order phase transition, explaining the stick-slip behavior through phase changes in a lubricant film, and predicts how system parameters influence this phenomenon.

Contribution

It introduces a phase transition framework to describe stick-slip friction, providing a new theoretical perspective on boundary lubrication dynamics.

Findings

Stick-slip mode results from periodic first-order phase transitions.

The model predicts system behavior based on internal and external parameters.

Boundary friction can be described as a phase transition phenomenon.

Abstract

A tribological system consisting of two contacting blocks has been considered. One of them is arranged between two springs, the other is driven periodically. The kinetics of the system has been studied in the boundary friction mode, when an ultrathin lubricant film is contained between the atomically smooth surfaces. In order to describe the film state, the expression for the free energy density is used in the form of an expansion in a power series in the order parameter, the latter being reduced to the shear modulus of a lubricant. The stick-slip mode is shown to be realized in a wide range of parameters, being a result of the periodic first-order phase transitions between kinetic friction regimes. The behavior of the system governed by internal and external parameters has been predicted.