Comparative study on tribological performance and mechanism of eco-friendly solvent-free covalent MXene nanofluids in glycerin and polyethylene glycol

Solvent-free covalent MXene nanofluids (MXene NFs) were prepared as eco-friendly additives to improve the dispersibility of MXene and the tribological performance of lubricants. Here, the tribological properties and tribo-mechanisms of MXene NFs additives in glycerin and polyethylene glycol (PEG 400) were evaluated, and pronounced differences were observed. In glycerin, the excellent anti-friction (28.9%) and anti-wear (98.0%) properties were realized after 0.5 wt% MXene NFs addition, for MXene NFs preferentially adsorbing onto the surface of friction pair and participating in the formation of tribofilm. However, in PEG 400, the poor friction-reducing and negative anti-wear performance were related to PEG 400 exhibiting high affinity towards steel substrate. This work provides a new approach for fabricating eco-friendly additives with excellent dispersion and lubricity. [Display omitted] •The solvent-free covalent MXene nanofluids (MXene NFs) are studied as green lubricating additives.•The MXene NFs exhibit long-term dispersibility in glycerin and PEG 400.•Clear differences were observed in the lubricating ability of the MXene NFs added into glycerin and PEG 400.•The mechanisms governing the tribological performance are different due to the adsorption behaviors.