Customizing tribological interface structure on TC6 alloy by plasma electrolytic oxidation and Ti₃C₂ nanocoating

To customize a self-lubricating tribological interface on titanium alloy surfaces and address the issues of high surface roughness and friction coefficient associated with porous plasma electrolytic oxidation (PEO) coatings, this study focused on the protective structure of the armadillo. A bioinspired “bone–skin” composite structure was designed by first depositing a high-strength coating (bone) on the titanium alloy surface via PEO, followed by the deposition of a Ti₃C₂ MXene nanocoating (skin) via a drop-casting method. The porous structure of the PEO coating enhances the confinement effect on the Ti₃C₂ nanoparticles, thereby improving their load-bearing capacity and significantly reducing interfacial friction and wear. This demonstrated a 67.8% increase in the microhardness and an order-of-magnitude reduction in the wear rate compared with those of the substrate. Tribological analysis revealed that the synergistic interaction between the low-shear Ti₃C₂ MXene nanoparticles and the TiO₂-rich wear debris led to the formation of a protective tribofilm at the contact surface, effectively achieving both friction reduction and wear resistance. Friction and wear tests under different conditions further confirmed the stability of the PEO–Ti₃C₂ MXene interface structure. This study presents a novel interfacial design strategy using PEO and Ti₃C₂ MXenes that results in excellent tribological properties, providing new insights for their application in tribology.