Tribological performance of journal bearings for fuel oil lubrication based on Ni-coated graphite hybrid microparticle and carbon fiber reinforced polytetrafluoroethylene composites

The application of polytetrafluoroethylene (PTFE) in lubricating bearings is typically limited since it lacks sufficient wear-resistance, loading capacity and thermal dissipation ability. Herein, PTFE composites reinforced with carbon fiber (CF) and different amounts of Ni-coated graphite (Ni@Gr) were developed. The tribological performance and enhancement mechanisms of developed composites and fabricated journal bearings under fuel oil with low viscosity and multiple wear conditions were investigated. The results showed that the compressive strength, thermal conductivity and dimensional stability were enhanced by increasing the loading of Ni@Gr microparticles. The incorporation of Ni@Gr further reduces the friction coefficient and wear rate and prolongs the wear life up to 10⁵ cycles when lubricated by fuel oil. With an optimal Ni@Gr filler loading, a high PV of up to 3.80 MPa m/s and a steady temperature rise below 60 °C were observed, revealing the tribo-potential in the fields of polymer bearings used under fuel oil lubrication. This work optimized PTFE composites by combining material design research and practical application, providing guidance for the development of sliding bearings in future fuel systems.