Relationship between Viscosity and Resistance of Oil Film: A New Way to Investigate the Controllable Friction between Charged Interfaces Lubricated by Ionic Lubricating Oil

Abstract Intelligent lubricating materials can control the coefficient of friction between interfaces in response to external stimuli. Considering that mechanical transmission parts are mostly used in oil‐based lubrication environments, the lubrication performance and electrical regulation mechanism of poly‐α‐olefin‐50 (PAO50), a lubricating oil, containing 1‐octyl‐3‐methylimidazolium hexafluorophosphate ([OMIm]PF 6 ), an ionic liquid (IL), are investigated in this study. Friction tests on a universal micro‐tribometer under current stimulation show that ionic lubricating oil has an excellent lubrication performance and electrical responsiveness. By changing the current strength, ion content, and the load, the reasons behind the change in the coefficient of friction are investigated. Ion aggregation results in an increase in the viscosity of the lubricating oil film, which leads to an increase in the coefficient of friction. Moreover, the real‐time resistance value of the oil film is obtained through a self‐built voltage acquisition device. The mechanism of the electronic control of friction is verified by analyzing the influence of the change in ion distribution on the resistance of the oil film. There is a correlation between the resistance and viscosity of the oil film. The results of this study may be significant in guiding research on the intelligent control of friction under oil‐based lubrication.