Synergistic lubrication of MXene/Bi₆O₇ heterostructures in polyimide composite coatings for enhanced tribological performance

Two-dimensional lubricating fillers play a crucial role in strengthening the tribological performance of polymer coatings. In this study, MXene-PDA-Bi 6 O 7 (MXene/Bi 6 O 7 ) heterostructured composite nanofillers were prepared via a mussel-inspired chemical method. Polyimide (PI) composite coatings with varying MXene:Bi₆O₇ mass ratios were fabricated, and their microstructure, mechanical properties, and tribological performance were systematically characterized. The loading of Bi 6 O 7 nanoflowers onto the surface of PDA-modified MXene was achieved through in situ assembly, resulting in the formation of MXene/Bi 6 O 7 heterostructures. The experimental results demonstrated that the synergistic effect of MXene and Bi 6 O 7 significantly enhanced the properties of the PI composite coatings. Specifically, when the MXene-to-Bi₆O₇ mass ratio was 4:6, the PI composite coatings exhibited an 11.2 % reduction in friction coefficient and a 70.5 % decrease in wear rate compared with pure PI. Additionally, the tensile strength of the PI matrix was increased to 185.99 MPa. The MXene/Bi 6 O 7 heterostructure effectively reduced direct contact between the friction pairs by forming a dense transfer membrane, thereby maintaining stable lubrication performance under a broad range of conditions. The study elucidates the role of two-dimensional heterostructures in enhancing the interfacial mechanics and tribological properties of polymers, providing theoretical guidance and technical routes for the development of high-performance abrasion-resistant polymer coating materials.