The Synergistic Effects of Modified Carbon Fiber and Multiwalled Carbon Nanotubes on the Tribological Properties of Polyetheretherketone Composites

In this study, the interfacial bonding between carbon fibers (CFs) and polyetheretherketone (PEEK) was enhanced via three modification strategies, namely, incorporation of multiwalled carbon nanotubes (MWCNTs) as filler, CF surface sizing with a polyethylenimine (PEI)-based agent containing MWCNTs, and CF functionalization using a polyamidoamine (PAMAM) coupling agent carrying MWCNTs. These approaches aimed at improving CF-PEEK compatibility through physical entanglement and chemical bonding. The addition of MWCNTs enhanced the mechanical interlocking, while amide bonds and π–π interactions in CF-PEI-MWCNTs/PEEK and CF-PAMAM-MWCNTs/PEEK systems further strengthened the interface. Designed for high-wear-resistance applications such as aerospace components and sliding bearings, the CF/PEEK composites were tested against GCr15 steel under dry friction conditions. Results showed that the CF-PEI-MWCNTs/PEEK composite exhibited superior mechanical and tribological performance compared to the MWCNTs-filled CF/PEEK system. The dominant wear mechanism was mild adhesive wear.