Hybrid MXene coatings: unlocking synergistic lubrication properties of Ti3C2Tx and Nb₂CTx MXenes for improved tribological performance

The development of advanced solid lubricants is critical for enhancing energy efficiency and durability in mechanical systems. In this study, we investigate the tribological performance of hybrid solid lubricant coatings composed of two-dimensional titanium carbide (Ti₃C₂T_x)- and niobium carbide (Nb₂CT_x)-based MXenes. Coatings were applied via spray deposition onto AISI 304 stainless steel substrates and tested under dry sliding conditions against Al₂O₃ counterbodies. While individual MXene coatings exhibited limited friction stability, the hybrid Ti₃C₂T_x/Nb₂CT_xcoating demonstrated a significantly reduced and stable coefficient of friction (COF < 0.2) throughout the test duration. Comprehensive surface and structural analyses of the wear tracks including SEM-EDS, Raman spectroscopy, and TEM revealed the formation of a compact, stratified tribofilm. We propose as a phenomenological model that under tribological stress, the hybrid system undergoes adaptive reconfiguration: Ti₃C₂T_x anchors to the substrate, enhancing adhesion and mechanical integrity, while Nb₂CT_x migrates to the sliding interface, acting as a sacrificial layer. This dynamic redistribution results in a synergistic interaction that enhances tribochemical resilience and wear resistance. These findings establish hybrid MXene coatings as a promising strategy for engineering next-generation solid lubricants, offering new pathways for the design of high-performance, energy-efficient coatings in demanding industrial applications.