Study on the friction properties of silane-modified MXene-reinforced polyimide and its applications in rotary engine sealing

Polyimide is a promising material for sealing applications, yet its performance under dry sliding remains a limiting factor. Introducing suitable fillers provides a feasible route to address this issue, particularly when interfacial behavior can be effectively regulated. Silane-modified Ti 3 C 2 T x MXene was incorporated into PI via ball milling and hot pressing, yielding composites with composition-dependent tribological responses. An optimum was observed at 0.25 wt%, where the friction coefficient (∼0.242) and wear rate (∼6.1 × 10 −5 mm 3 /(N·m)) were reduced by about 39% and 37.6%, respectively, compared with neat PI. The improvement is linked to more uniform filler dispersion and a stabilized sliding interface, while higher loadings tend to induce aggregation and interfacial instability, leading to deteriorated performance. Rotary-engine back-drag tests further confirmed that the optimized composite reduces friction torque relative to silicon bronze and silicon nitride, while maintaining comparable or higher peak cylinder pressure. These results indicate its potential of silane-modified Ti 3 C 2 T x MXene/PI composites for rotary-engine radial sealing.