Effect of Plastic Deformation and Damage Development during Friction of fcc Metals in the Conditions of Boundary Lubrication

Alexey Moshkovich,Lev Rapoport,Vladislav Perfilyev

doi:10.3390/lubricants7050045

Abstract

The main goal of the presented work was the analysis of the interaction between deformed microstructures and friction and the wear properties of four face centered cubic (fcc) metals. Pure fcc metals such as Ag, Cu, Ni, and Al with different values of stacking fault energy (SFE) were chosen for pin-on-disk tests in lubricated conditions. Friction properties of the four fcc metals are presented herein as their Stribeck curves. The transition from elasto-hydrodynamic lubrication (EHL) to boundary lubrication (BL) regions depends mainly on the values of SFE, hardness, and contact temperature. The acoustic emission (AE) parameters were analyzed in the transition from the EHL to the BL region. The models of friction in different lubricant conditions related to the AE waveforms were proposed. The nanocrystalline top surface layers characterized the deformed structure during friction of Ag in the BL region. The lamellar cross-sectional microstructure was formed in the subsurface layers of Ag, Cu, and Ni in the friction direction. Steady state friction and wear in the BL conditions were explained by a balance between the hardening and the dynamic recovery, which was strongly dependent on the SFE and the temperature. The interaction between the deformed structure, the friction, and the wear properties of the studied metals rubbed in the BL region is discussed herein.

Highlights

Friction and wear processes are very complex phenomena based on the deep understanding of multidisciplinary and multiscale effects of contact interaction, plastic deformation, and damage development in different environmental conditions
Excellent analysis of modeling and simulation in tribology was recently presented in the review from [1], where different models based on the contact mechanics were carefully discussed, as was the importance of developing new models with consideration to the dislocation dynamic during friction
The insert demonstrates the details of friction behavior at the maximal load in the boundary lubrication (BL) region

Summary

Introduction

Friction and wear processes are very complex phenomena based on the deep understanding of multidisciplinary and multiscale effects of contact interaction, plastic deformation, and damage development in different environmental conditions. If theoretical and experimental models of asperity contact are widely studied, the number of publications concerning the effect of plastic deformation and damage development during friction is limited. The dislocation structure of surface layers under dry friction was originally studied by Rigney with colleagues [2,3,4,5] and Garbar [6,7]. [9] The structure of the high-deformed layers of the top surface layers during friction and wear was Lubricants 2019, 7, 45; doi:10.3390/lubricants7050045 www.mdpi.com/journal/lubricants A plateau range of high-deformed layers was reached at the end of the running-in process of steel and was preserved in the steady friction state. [9] The structure of the high-deformed layers of the top surface layers during friction and wear was Lubricants 2019, 7, 45; doi:10.3390/lubricants7050045 www.mdpi.com/journal/lubricants

Methods

Results

Conclusion