Highly lubricating and wear-resistant Ti₃C₂T_x@SiO₂/PI composites based on the action of transfer film at the friction surface

Polyimide (PI) is a special engineering plastic, widely involved in mechanical components, instruments, and petrochemicals. However, single PI material is inevitably subject to wear and tear in practice, which leads to weakened material properties. In this work, Ti₃C₂T_x@SiO₂ was prepared to enhance the wear resistance and lubrication properties of PI by intercalating SiO₂ into the interlayer of Ti₃C₂T_x sheets. Ti₃C₂T_x@SiO₂/PI composites were fabricated in two steps to test the tribological performances. SiO₂ particles change the form of interfacial friction from sliding to rolling, thus relieving direct friction between material and steel ball. So, the composites have a minimum COF (COF = 0.33) when the content of Ti₃C₂T_x@SiO₂ is 0.80 wt%. Moreover, the average value of wear rate was 0.24 × 10⁻⁵ mm³/(N·m) when Ti₃C₂T_x@SiO₂ content was 1.60 wt%, which was 91.0% lower compared to the PI matrix. During the friction process, the abrasive chips of the material migrate to the surface of the steel ball to form a transfer film, which protects the material and thus reduces the wear rate. Therefore, the hybrids Ti₃C₂T_x@SiO₂ are effective and important wear-resistant agents and solid lubricants to improve the wear resistance and lubricity of PI or other polymer materials. Highlights: SiO₂ insert Ti₃C₂T_x is a key factor in changing sliding friction into rolling friction, effectively reducing the COF. The average wear rate was 91.0% lower than that of the polyimide matrix when Ti₃C₂T_x@SiO₂ content was 1.60 wt%. The minimum COF of Ti₃C₂T_x@SiO₂/PI composites reached 0.33 when the content of Ti₃C₂T_x@SiO₂ was 0.80 wt%. The transfer film effectively reduces further wear of the material during friction.