Tribological performance of WS₂/PAI composite coating reinforced with carbon nanotubes‐carbon fiber at high temperatures

The carbon nanotubes (CNTs) were chemically grafted onto carbon fibers (CFs) to prepare a CNTs‐CF multiscale reinforcement. The tungsten disulfide/polyamide‐imide (WS 2 /PAI) composite coating, with PAI as the binder and WS 2 as the lubricant filler, was prepared. The enhancement mechanism of CNTs‐CF on the high‐temperature tribological performance of WS 2 /PAI composite coating was analyzed. The addition of CNTs‐CF was found to increase the temperature of the 10% mass loss of PAI by 14.2°C, indicating its ability to improve the thermal stability of the coating. The hardness of the CNTs‐CF‐modified WS 2 /PAI composite coating was measured to be 17.9% higher than that of the WS 2 /PAI substrate. The incorporation of CNTs‐CF significantly improved the tribological performance of the WS 2 /PAI composite coating. Particularly at 200°C, the friction coefficient and wear rate of CNTs‐CF modified WS 2 /PAI composite coating were only 0.095 and 8.92 × 10 −5 mm 3 /(N·m), respectively, which decreased by about 70.3% and 62.2% compared to the WS 2 /PAI substrate. Further analysis revealed that CNTs‐CF is firmly embedded within the WS 2 /PAI composite coating through the synergistic mechanism of mechanical interlocking and molecular adsorption. Furthermore, CNTs‐CF formed a stable lubricating film, ensuring the excellent friction and wear performance of the coating. Highlights The CNTs‐CF can mitigate the thermal degradation of PAI. The high‐temperature wear resistance of the coating was noticeably improved. The problem of CF easily detaching from the coating was resolved. The main components of the transfer film were analyzed.