Ultra-low wear in multifunctional Ti₃C₂T_x/PI composite films induced by tribo-chemistry mechanism

Ti₃C₂T_x MXene was cooperated with polyimide (PI) to improve the wear resistance of the PI matrix under complex working conditions. Compared to the pristine PI, the Ti₃C₂T_x/PI composites have excellent frictional properties, specifically, the coefficient of friction is 0.32 and the wear rate is 0.62 × 10⁻⁵ mm³/(N·m). The composites formed a transfer film on the contact surface during the friction process, and the transfer film prevents direct contact between tribo-couples. The results studied by Raman and XPS showed that the transfer film contains TiO₂ that is derived from oxidized Ti₃C₂T_x. Moreover, the tribological mechanism has been summarized as two aspects: On one hand, the relative sliding of the Ti₃C₂T_x lamellae transfers the sliding stress. On the other hand, a transfer film is created between Ti₃C₂T_x/PI composites and steel ball during friction that prevents further wear of the material. All in all, two-dimensional MXene can effectively improve the wear resistance of the polymer matrix and has the potential to be used in friction-protective layers under complex working conditions.