Superlubrication of poly-α-olefin-8 (PAO8) enabled by MXene/PI coating

Polyimide (PI) coatings are highly valued for their easy processing and exceptional mechanical qualities, which enable them to be applied in a variety of approaches. By integrating MXene, a two-dimensional material renowned for its low shear strength and excellent load-bearing capacity, into the PI matrix and subsequently using it as a coating on GCr15 surfaces, MXene/PI composites were produced. The tribological performance of these composites improved with increasing MXene content and then decreased. Under dry state and lubricated with PAO8, 0.25%MXene/PI composite demonstrated optimal tribological performance and achieved superlubricity, with its COF was only 0.002 and its wear rate was merely 1.92×10^-7 mm³·N^-1·m^-1. This improvement can be attributed to the even distribution of MXene in the PI matrix, particularly during frictional processes, as evidenced by SEM, DMA, and TEM analyses. Furthermore, the interaction between MXene and PI was confirmed through XPS analysis. These results not only establish the groundwork for developing high-performance PI coatings but also provide valuable insights for designing composite materials with superlubricity properties in engineering applications.