Tribological Properties of Polyetheretherketone Composites: Synergistic Effects of Polytetrafluoroethylene and Nano-Zirconia

To address the severe wear issues faced by sliding bearing materials in wind turbine main shafts and high-pressure low-speed hydraulic pump/motor tribo-pairs under low-speed, heavy-load, and poorly lubricated or even dry friction conditions, this study fabricated polyetheretherketone (PEEK) composites modified with polytetrafluoroethylene (PTFE) and nano-zirconia (nano-ZrO2), both individually and in combination, via hot-press molding. The thermal properties, surface mechanical characteristics, and tribological behavior of the composites was systematically investigated under multi-level heavy-load dry friction conditions (35∼93 MPa). Results indicate that single-filler modifications (PTFE or nano-ZrO2) improve tribological performance under specific conditions but exhibit severe wear degradation under high loads. In contrast, dual-filler composites demonstrate stable and superior tribological performance across the entire load range, with friction coefficients and wear rates reduced by 38.0%∼76.4% and 82.9%∼92.7%, respectively, compared to pure PEEK. Mechanism analysis reveals that PTFE forms a low-shear-strength lubricating transfer film at the interface, while Nano-ZrO2 serves as physical anchoring sites to enhance film stability and bridge interfacial microcracks caused by differential deformation between PTFE and the PEEK matrix under extreme loads. The synergistic effect effectively enhances lubrication and mitigates thermal wear. This study provides theoretical insights and material design strategies for polymer-based bearing materials operating under extreme service conditions.