Investigating the tribological synergy between ionic liquids and Ti₃C₂Tₓ MXenes under different load, sliding, and temperature conditions

Abstract

Ti₃C₂Tₓ MXenes are applied to two different ionic liquids (ILs) P8881(BuO)₂PO₂⁻ and P8881(MeO)₂PO₂⁻ referred to as IL1 and IL2 respectively. Their effectiveness as potential lubricants was evaluated using a Mini-Traction Machine (MTM) tribometer, where tribofilm formation was observed in-situ and further analyzed through ex-situ techniques, including transmission electron microscopy (TEM), Raman spectroscopy, and laser microscopy. The results indicate that MXene-modified ILs enhance interfacial frictional performance, but their performance is highly dependent on test conditions. MTM tests reveal that MXene-modified ILs may perform poorly under mild conditions due to interference with the formation of a lubricating oil film and changes in viscosity. However, they significantly reduce the friction coefficient under harsh conditions (low speed, high load, and high temperature). Notably, the IL1 with 1 wt.-% of MXenes added shows optimal friction performance at 80 °C, with a decrease of about 80.5 % in coefficient of friction (COF) compared to the pure IL. TEM confirms that MXenes can actively integrate into the amorphous tribofilm, accumulating and aligning in surface defects, thereby reducing the COF. This demonstrates the lubrication performance of MXene nanosheets and ILs and highlights the potential of MXene-modified ILs as novel lubricants.