Tribological improvement using Ti3C2Tx MXenes and/or CaCO3 nanoparticles as lubricant additives

The main goal of this work is the tribological characterization of low viscosity nanolubricants, PAO8 base oil containing Ti 3 C 2 T x MXenes and/or functionalized CaCO 3 (CaCO 3 -OA) nanoparticles as additives. Friction enhancements were reached with CaCO 3 -OA nanolubricants with maximum reductions of 44 % for the optimal concentration of 0.10 wt% CaCO 3 -OA. With respect to wear, significant improvements in antiwear performance were achieved with maximum reductions in wear width of 27 % (0.15 wt% CaCO 3 -OA), 14 % (0.10 wt% Ti 3 C 2 T x ) and 13 % for hybrid (0.10 wt% CaCO 3 -OA/Ti 3 C 2 T x ) nanolubricants. Confocal Raman microscopy was utilized to recognize the mechanisms that govern tribological improvement: tribofilm formation for Ti 3 C 2 T x nanosheets and tribofilm formation and self-repairing for CaCO 3 -OA nanoparticles. • Ti 3 C 2 T x and CaCO 3 -OA NPs were synthesized and fully characterized. • 0.10 wt% CaCO 3 -OA was the optimal friction performance (44 % reduction). • 0.15 wt% CaCO 3 -OA was the optimal antiwear behavior (27 % width reduction). • Lubrication mechanisms can be explained by tribofilm formation and self-repairing.