Tribological Behavior of Ionic Liquid with Nanoparticles

Abstract

This research aims to formulate a new lubricant containing oxide nanoparticles for enhancing anti-wear ability and reducing friction. Different concentrations of copper oxide (CuO) and zinc oxide (ZnO) nanoparticles were separately added to an ionic liquid, methyltrioctylammonium bis(trifluoromethylsulfonyl)imide [N1888] [NTf2], to formulate the tested lubricants. The tribological properties of the lubricants were tested by performing ball-on-disc wear tests on a tribotester (MTM, PCS Instruments). The results show that both the CuO and ZnO nanoparticles can increase the friction reduction ability of the ionic liquid when used as a neat lubricant. The anti-wear characteristic of the ionic liquid is increased by adding ZnO nanoparticles but decreased by adding CuO nanoparticles. The best tribological performance observed for the concentration of 0.2 wt% ZnO, with the wear scar diameter is reduced by 32% compared to the pure ionic liquid. The results of SEM/EDX analysis on the worm morphologies show different lubrication mechanisms of the nanoparticles in the [N1888] [NTf2], which are tribo-sintering for CuO nanoparticles, and third body with pure rolling effect for ZnO nanoparticles.

Contact Characteristics at Interface in Three-Body Contact Conditions with Rough Surfaces and Foreign Particles

“…In the recent development of lubricants, adding particles to lubricants is one of the important directions because they can enhance the lubricant's interfacial tribological properties. Among factors affecting the tribological performance of nanolubricants, the size and concentration of nanoparticles have been widely studied [1][2][3][4][5][6][7][8]. However, in the literature reports on particle additives, the optimal particle size or optimal concentration for different interface conditions varies greatly.…”

“…The addition of 0.3 wt% nanoparticles resulted in a good improvement in reducing friction, wear and scar formation on the surface. Ta et al [7] added different concentrations (0.2 and 0.5 wt%) of CuO and ZnO nanoparticles to the ionic liquid. This method could enhance the anti-wear ability and reduce friction of the ionic liquid.…”

“…To simplify the analysis, this study assumes that both φ a (x) and φ(z) are Gaussian distributions, as shown in Equation (7) and Equation ( 8) [42]: 7)…”

Evaluation of tribological behavior of a circulation oil with ionic liquid and hybrid additives

“…In the third body mechanism, the ZnO NPs function as nano ball bearings, effectively transferring sliding friction into rolling friction and reducing the real contact pressure, resulting in low friction and wear. 47,54 Thus, the anti-wear mechanism of IL remains unchanged while the role of NPs switches from the most tribofilm formation to the most nano bearing effect in the hybrid nanolubricant R + IL + ZnO. Several studies have pointed out that ZnO NPs exhibited different wear mechanisms according to the base oil.…”

“…51 A few studies have revealed that [N 1888 ] [NTf 2 ] could improve friction-reducing and wear-reducing properties when it serves as a neat lubricant 36,52 or additive in oils. 53 Ta et al 54 found that the IL formulated with ZnO NPs could enhance the tribological properties of IL when used as a neat lubricant in steel–steel contacts. However, interactions between [N 1888 ] [NTf 2 ] with other additives when used as hybrid nanolubricants in lubricating oils have not been studied.…”