INFLUENCE OF POLYMER COMPOSITION ON WEAR OF METAL-SURFACE DURING FRETTING OF STEEL ON POLYMER

The effects of the nature of the polymer on the amount of metal wear during fretting of steel on polymers in laboratory air have been studied under a range of loads (130-330 g), amplitudes (3-10 μm) and frequencies (30-60 Hz). A number of polymers can cause damage to the metal, which takes the form of adhesive transfer of α-Fe2O3 particles to the polymer surface. The amount of metal wear depends on the polymer counterface and, under a given set of experimental conditions, increases in the order polytetrafluoroethylene (PTFE) and polyethylene, polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), polysulphone, Polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polycarbonate, nylon 66. No metal wear occurs when the counterface is PTFE and only occurs with polyethylene when the amplitude is greater than 7 μm. These differences are explained in terms of the adhesive properties of the polymers, as determined by their surface energetics. Wear of the polymer during fretting takes the form of fibre formation for polysulphone, PVC, polycarbonate, nylon 66 and, to a small extent, polyethylene, while it takes the form of a transfer of a polymer film to the metal for PTFE and PVDF. No polymer wear occurs for PCTFE or PMMA. © 1978.