Investigation of the tribological performance of ionic liquids in non-conformal EHL contacts under electric field activation

Abstract

Real-time external alteration of the internal properties of lubricants is highly desirable in all mechanical systems. However, fabricating a suitable and effective smart lubricant is a long-lasting experimental process. In this study, the film thickness and frictional response of ionic liquid-lubricated non-conformal contacts to an electric field excitation under elastohydrodynamic conditions were examined. Film thickness was evaluated using a "ball-on-disc" optical tribometer with an electric circuit. Friction tests were carried on a mini traction machine (MTM) tribometer with a "ball-on-disc" rotation module and an electric circuit for contact area excitation. The results demonstrate that there is a difference in the behaviour of the ionic liquid during electric field excitation at the evaluated film thicknesses. The results of evaluated film thicknesses demonstrate that there is a difference in the behaviour of the ionic liquid during electric field excitation. Therefore, the ionic liquids could be a new basis for the smart lubrication of mechanical components. Moreover, the proposed experimental approach can be used to identify electrosensitive fluids. Friction 8(5): 982-994 (2020) 983 |www.Springer.com/journal/40544 | Friction http://friction.tsinghuajournals.comFriction 8(5): 982-994 (2020) | https://mc03.manuscriptcentral.com/frictionFriction 8(5): 982-994 (2020)

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

“…ILs have high electrical responsiveness. [ 46 ] Through our experiment on the electric control of friction, it was found that the base lubricating oil could respond quickly to the electric stimulation with only a small amount of IL. According to the friction and wear experiment, the surface wear of the friction pair was almost zero when the load was 2.5 N. To minimize the influence of the change of the interface contact forms of the friction pairs on the experimental results, the electrically controlled friction experiment was first carried out in the reciprocating module under the load of 2.5 N at 25 °C, and the other parameters were consistent with the setting of the friction and wear experiment.…”

“…This caused an instant increase in viscosity, and the sliding movement required overcoming sticky resistance, showing an increase in the coefficients of friction. [ 46 ] As the circuit current increased, the attraction between the tribo‐pairs increased and more ions moved to the lubrication layer, which further increased the viscosity resistance, resulting in a larger coefficient of friction. In contrast, the lubricant had a liquid‐like structure with significantly weaker intermolecular binding force when little or no current was applied, resulting in a smaller coefficient of friction.…”

“…ILs have high electrical responsiveness. [46] Through our experiment on the electric control of friction, it was found that the base lubricating oil could respond quickly to the electric stimulation with only a small amount of IL. According to the friction and wear experiment, the surface wear of the friction pair was almost zero when the load was 2.5 N.…”

“…[ 21 ] Using the electric field regulation mechanism, the influence of film thickness on the friction of pure ILs under an electric field was observed by using a “ball‐on‐disk” optical tribometer. [ 46 ] In order to enhance the response of the ILs to electrical stimulation, solvent‐free ionic nanofluids of silica with different corona molecule structures were synthesized. By applying a relatively low electric potential to the nanofluids, an enhanced double electric layer was generated, which could rapidly and significantly reduce the friction.…”

Influence of the air pressure and oil amount to the temperature of the high-speed bearings lubricated by oil mist

“…Numerical computational fluid dynamics and theoretical approaches to describe the mechanisms of oil injection in case of lubrication of high-speed spur gears were presented by Wang et al (2018). Finally, producing smart lubricants is also an up-to-date approach that can be used for high-speed assemblies (Michalec et al , 2020).…”