Experimental investigation of tribological performance of PTFE-derived solid lubricants in sliding building bearings

Friction pendulum systems (FPS) and sliding bearings are widely used in bridges and buildings for seismic isolation. As their engineering applications increase, there is a growing need to understand the overall tribological performance of sliding-type bearings under severe earthquake conditions. Solid lubricants are the thin layers of polymer installed between the bearing sliding interfaces, and predominate the tribological performance of bearings. Despite advances in material science, few studies have investigated the tribological performance of bearings under seismic action. This study aimed to address this issue by conducting 48 tests with different pressure (15-50 MPa) and peak velocity (4-200 mm/s) levels using three commercially available solid lubricant formulas derived from polytetrafluoroethylene (PTFE). All lubricants exhibited a decrease in the friction coefficient as the pressure level increased. The friction coefficient increased with the peak velocity before 100 mm/s, and remained approximately constant thereafter. The surface wearing mechanism of filler-modified lubricants was different to that of unfilled PTFE. The wearing profile of lubricants was mostly pressure-insensitive and velocity-sensitive. The experimental results demonstrate the significant effect of the pressure and peak velocity on the friction coefficients and wear of bearing lubricants, and provide valuable insights for the design of future solid lubricants in FPS and other sliding bearings for aseismic applications.