Remarkable Lubricating Effect of Ionic Liquid Modified Carbon Dots as a Kind of Water-Based Lubricant Additives

Abstract

Ionic liquid modified carbon dots (CDs-IL) were successfully synthesized by one-pot pyrolysis. The tribological properties of CDs-IL as a kind of water-based lubricant additive were investigated under four-ball mode. The experimental results demonstrated that the added CDs-IL not only increased load-carrying capacity of base liquid but also displayed remarkable friction-reducing and antiwear properties. At an optimal concentration of 0.05[Formula: see text]wt.% and a proper load of 50[Formula: see text]N, the mean friction coefficient and wear volume reduced by 65% and 60%, respectively. The remarkable lubricating effect of CDs-IL was attributed to the boundary tribofilm formed by absorption and deposition of CDs-IL on rubbing surfaces. The lubricating effect of CDs-IL especially antiwear effect greatly attenuated when the load was lower or higher than 50 N because the function of deposition tribofilm formed by CDs-IL was suppressed by the absorption tribofilm or tribochemical film derived from triethanolamine in base liquid, respectively.