Electrochemical current at reciprocating contacts: A new analytical modelling

Abstract

Using the principles of passivation conjectures, an analytical model was proposed to closely link the mechanical and electrochemical parameters at a rubbing interface for describing the currents emitted by both the contacting materials in a ball-on-disk configuration. The current equations for the passive disk and ball were unified to formulate the current for a metal-on-metal (MoM) contact. The developed model was assessed using a customised tribocorrosion apparatus across two types of tribocouples, zirconia-on-CoCr and CoCr-on-CoCr, tested in phosphate buffered saline solution at reciprocating frequencies of 1, 5, 10, and 20 Hz. The wear tracks were characterised using surface profilometry, confocal microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. After the verification, the model was used to study the roles played by both the disk and ball components in the electrochemical current at MoM contacts. The results of this analytical model clearly indicated the pivotal influence of testing parameters in constructing the unique patterns of partial currents and the dominant component (disk/ball) in establishing the electrochemical current at an interface.