Tribological performance of recyclable oil-soluble magnetic MXene as efficient lubricant additives under boundary lubrication conditions

The design and synthesis of efficient lubricant additives based on MXene, an emerging two-dimensional layered material, have attracted increasing attention. In this study, a recyclable oil-soluble magnetic MXene (C12PA- MXene@Fe3O4) was synthesized through in-situ loading Fe3O4 nanoparticles on MXene nanosheets, and subsequently modified with dodecylphosphonic acid. The tribological performance of the synthesized additive was investigated under varying boundary lubrication conditions. The results show that the addition of 0.5 wt% C12PA-MXene@Fe3O4 reduced the average friction coefficient (AFC) and the wear volume by 14.8 % and 95.0 %, respectively, when compared to the base oil. The pronounced tribological performance of C12PA-MXene@Fe3O4 is attributed to its good dispersibility and the synergistic effect of MXene nanosheets and Fe3O4 nanoparticles. The MXene nanosheets work as carriers for Fe3O4 nanoparticles, preventing their aggregation. Moreover, the Fe3O4 nanoparticles, when loaded on MXene nanosheets, facilitate the sliding of MXene layers by expanding the interlayer spacing. After the tribological test, a continuous and relatively smooth tribofilm forms on the surface, with a thickness ranging from 38 to 80 nm, which is composed of phosphate ions, titanium oxide, and iron oxides. The tribofilm prevents the direct contact of rubbing surfaces, contributing to the superior anti-wear performance.