Ti₃C₂T_x MXene Nanosheets as Lubricant Additives to Lower Friction under High Loads, Sliding Ratios, and Elevated Temperatures

Tribological studies using 2D nanomaterials have gained notable attention in the last decade owing to their outstanding friction and wear performance. Within this group, MXenes are an emerging class that has moved into the focus of tribological research due to their easy-to-shear ability, favorable mechanical properties, and ability to generate beneficial tribo-films. The present study aims at scrutinizing the tribological performance of multilayer Ti₃C₂T_x MXene nanosheets when used as a lubricant additive in poly-(α)-olefin oil under non-conformal contact conditions. Ball-on-disc tests were carried out at varying speeds, temperatures, loads, slide-to-roll ratios, and MXene concentrations (0.5 and 3 wt %) to assess their performance over a broad range of experimental conditions. Our results demonstrate that multilayer Ti₃C₂T_x MXenes (3 wt %) considerably reduced the coefficient of friction under most conditions considered. Particularly, under severe conditions (higher loads, sliding ratios, and elevated temperatures), which result in reduced film thicknesses and harsher contacts, MXenes showed a notable friction reduction of about 30%. Therefore, multilayer Ti₃C₂T_x MXene nanosheets demonstrated excellent potential as lubricant additives for components that operate under severe and varying working conditions.