Numerical Study on Thin Film Lubrication Performance with Imperfect Coating under the Effect of the Electrical Double Layer in Point Contact

Abstract

Revealing the interface effect on lubrication is great significance for designing high performance water-based lubricating friction pairs. In this study, a new thin film lubrication numerical model considering the electrical double layer (EDL) effect with an imperfect coating in point contact is proposed, and the validity and effectiveness of the model is verified. The numerical results show that increasing the zeta potential increases the film thickness, which indicates that the EDL effect can improve the firm lubricated film formation. However, the effect of the zeta potential on the von Mises stress is very small because the liquid film pressure remains constant at different surface potentials. On the other hand, with an increase in coating thickness, the effects of the coating on the film thickness and pressure gradually become evident, but the von Mises stress is affected by the imperfectly bonded interface and coating thickness. Finally, the effect of surface roughness on thin film lubrication was analyzed. The liquid film thickness slightly decreased and the occurrence of stress concentration on the surface coating was evident. The proposed model was expected to provide a calculation basis for solving the thin film lubrication problem of coatings affected by the EDL.

Keywords

• electrical double layer
• imperfect coating–substrate interface
• thin film lubrication
• numerical study