Combining Tailored Ionic Liquids with Ti₃C₂Tₓ MXenes for an Enhanced Load‐Carrying Capacity Under Boundary Lubrication

Abstract

To improve the efficiency and lifetime of mechanical components, new lubrication systems are needed. Two complementary material classes, which have demonstrated a promising tribological performance, are ionic liquids and MXenes (2D transition metal carbides and nitrides). Herein, Ti₃C₂Tₓ MXenes are used as additives in ionic liquids (ILs) to improve their load-carrying capacity under boundary lubrication. The specifically synthesized ILs share the same cation (trioctyl(methyl)phosphonium) but different anions (dimethyl phosphate and dibutyl phosphate for IL1 and IL2, respectively) to assess the effect of the anion's alkyl chain length. The wear reduction performance is tested with a cylinder-on-ring contact in a standardized Brugger tester, which is suitable to study boundary lubrication and to assess the antiwear ability of the IL/MXene lubricant blends. MXenes indicate an excellent dispersibility in both ILs over 24 h. It is found that, irrespective of the used IL, the addition of MXenes always increases the load-carrying capacity. Particularly, significantly reduced wear and thus a high load-carrying capacity are observed for the combination IL2/MXenes, which also outperform fully formulated commercially available lubricants such as turbine oils.