Researchers at the Faculty of Mechanical Engineering, specifically within the Laboratory for Tribology and Interface Nanotechnology (TINT), have shown that electrical potential can strongly change how a lightweight, high-performance polymer composite behaves during sliding. The study found that moderate electrical potentials can sharply increase friction and wear, while higher potentials can reduce them again through thermally assisted softening. The findings can help improve the reliability and durability of polymer components used in increasingly electrified mechanical systems.
Electric vehicles and other electrified mechanical systems increasingly rely on lightweight polymer composites in components such as bearings, gears and other sliding contacts. These materials offer low density, good mechanical and chemical resistance and low friction, but the presence of electrical potentials can introduce additional tribological challenges. Until now, the effects of electrification on high-performance polymer composites have been much less understood than those in conventional metal contacts.
The study investigated carbon-fiber-reinforced PEEK, a high-performance engineering polymer, sliding against a steel ball under dry conditions while applying electrical potentials from 0 to 30 V. The experiments showed a non-monotonic response: friction increased from about 0.24 at 0 V to about 0.30 at 15–20 V, while the specific wear rate of the polymer increased from 4.25 × 10⁻⁷ to 6.76 × 10⁻⁶ mm³/Nm at 20 V. At 30 V, friction fell to about 0.19 and wear decreased by around 70% compared with 20 V, although it remained higher than under non-electrified conditions. Surface analyses revealed increasing material transfer, severe wear and fibre exposure at intermediate potentials, while higher potentials were associated with polymer transfer and a smoother worn surface. Based on these observations, the researchers propose that electrical effects, frictional heating, Joule heating, oxidation and mechanical damage act together, producing different wear regimes as the applied potential changes. The work provides a potential-dependent framework for understanding and controlling electrified polymer–metal contacts and may contribute to more reliable and durable components for electric mobility.
“Our results show that electrical potential does not simply increase or decrease friction and wear. Instead, the material passes through different regimes as the potential changes. Understanding these transitions is important for designing polymer components that can operate reliably in electrified mechanical systems.” — Neuma Pereira
Future research will focus on clarifying the electrical and chemical interactions at the sliding interface and on identifying potential thresholds that can be used to improve the durability and reliability of polymer composites in electrified applications.