Thermodynamics and kinetics of boundary friction

TL;DR

This paper develops a deterministic thermodynamic and kinetic model for boundary friction involving ultrathin lubricants, analyzing how temperature, shear velocity, and pressure influence friction and describing stick-slip behavior.

Contribution

It introduces a novel parameter of excess volume to describe lubricant state and provides a comprehensive model for thermodynamics and shear melting in boundary friction.

Findings

Friction force depends on temperature, shear velocity, and pressure.

The model describes the stick-slip mode with periodic melting and solidification.

Qualitative agreement with experimental data is achieved.

Abstract

A deterministic theory describing the behavior of an ultrathin lubricant film between two atomically-smooth solid surfaces is proposed. For the description of lubricant state the parameter of excess volume arising due to chaotization of solid medium structure in the course of melting is introduced. Thermodynamic and shear melting is described consistently. Dependences of friction force on temperature of lubricant, shear velocity of rubbing surfaces, and pressure upon surfaces are analyzed. Within the framework of a simple tribological model the stick-slip mode of friction, when the lubricant periodically melts and solidifies, is described. The obtained results are qualitatively compared with the experimental data.