Tribological behavior and mechanism of Mo₂Ti₂C₃/polyimide composite films under dry friction condition

Polyimide (PI) has good mechanical properties and thermal stability, while high coefficient (COF) and wear rate limit its wide application. In order to endow PI with better friction and wear resistance, Mo₂Ti₂C₃ MXene was used as solid lubricant to prepare Mo₂Ti₂C₃/PI nanocomposites with different content of Mo₂Ti₂C₃. The effect of the amount of Mo₂Ti₂C₃ on the tribological behavior of PI was explored and the tribological mechanism was also analyzed Tribological tests showed that at 1.2 wt% of Mo₂Ti₂C₃ addition, the composite material demonstrated superior friction and wear resistance, exhibiting a 19.9% decrease in the COF and a 79.7% decrease in the wear rate compared to single PI due to the good self-lubricating properties of Mo₂Ti₂C₃ MXene. Moreover, Mo₂Ti₂C₃ can also effectively assist PI to form sleek transfer films without interruption or gaps on the steel balls, resulting in a reduced friction COF and wear rate of the material. This work demonstrates that Mo₂Ti₂C₃ MXene is an aussichtsreich additive for polymers to improve the tribological properties and broadens the applications of Mo₂Ti₂C₃/PI composites in friction material area. Highlights: Mo₂Ti₂C₃ significantly improves the tribological performance of polyimide. The thermal properties of Mo₂Ti₂C₃/polyimide are enhanced by the introduction of Mo₂Ti₂C₃. The minimum coefficient of Mo₂Ti₂C₃/PI composites was only 0.246 at the 1.2 wt% content of Mo₂Ti₂C₃. The wear rate of Mo₂Ti₂C₃/PI composites was decreased by 79.7% at the 1.2 wt% addition of Mo₂Ti₂C₃. Mo₂Ti₂C₃ promotes the establishment of tribo-film to protect the Mo₂Ti₂C₃/PI composites from friction.