Towards programmable friction: control of lubrication with ionic liquid mixtures by automated electrical regulation

Abstract

For mechanical systems in relative motion it would be fascinating if a non-mechanical stimulus could be used to directly control friction conditions. Therefore, different combinations of lubricants and external triggers for tribological influence have already been investigated. We show that when two metallic friction partners are lubricated with ionic liquid mixtures (ILM), consisting of long-chain cation and two different high charge/mass ratio anion containing ILs, the application of an electric impulse induces a permanent change of the frictional response. Such mixtures are able to alter the coefficient of friction (COF) to a greater extent, more accurately and faster than the respective single-component ILs. This change in the frictional properties is presumably due to changes in the externally induced electrical polarization at the surface, which influences the molecular adsorption, the exchange of adsorbed ions and their molecular orientation. The correlation between surface charges and friction can be used to control friction. This is achieved by implementing an electric tribo-controller which can adjust preset friction values over time. Programming friction in this way is a first step towards tribosystems that automatically adapt to changing conditions.

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

“…[47] Using external electrical control, Gatti et al proposed the concept of programmable control of friction, which could control the adsorption, exchange, and orientation of multicomponent ILs on a surface by changing the polarization of charged friction surfaces using a compiled program, to change the coefficient of friction to a greater extent more accurately and faster. [48] Although ILs seem to be a suitable and smart alternative to conventional lubricants, their current high manufacturing costs make their direct application as lubricants impractical. In addition, current studies focus more on the lubrication mechanism of ILs, although some studies have reported on the lubrication conditions of pure ILs under the influence of electric fields.…”

The effect of anion architecture on the lubrication chemistry of phosphonium orthoborate ionic liquids

“…The changing technological landscape, with the rapid shift towards vehicle electrification and green energy production being the obvious examples, along with environmental concerns, has resulted in a need for lubricants with enhanced functionality such as electrical responsivity 11 – 14 . It is the role of chemists to facilitate the tribological advances by developing new formulations, sometimes even with new molecules, in an attempt to feed the industrial and societal demands.…”

The Effect of Anion Architecture on the Lubrication Chemistry of Phosphonium Orthoborate Ionic Liquid

“…10 The changing technological landscape, with the rapid shift towards vehicle electri cation and green energy production being the obvious examples, along with environmental concerns, has resulted in a need for lubricants with enhanced functionality such as electrical responsivity. [11][12][13][14] It is the role of chemists to facilitate the tribological advances by developing new formulations, sometimes even with new molecules, in an attempt to feed the industrial and societal demands.…”