Abstract
Polyamide 4,6 (PA46) and its aramid fibre composites (6 wt.%, 12 wt.% and 15 wt.%) were tested as candidate materials for tribological applications using a twin-disc wear test rig, built in our laboratories, to measure their wear and frictional properties under variations of number of cycles (10 3 to 10 6), applied load (300–600 N) and applied velocity (500, 1000 and 1500 rpm), all at a slip ratio of 2%. The rig uses polymer-on-polymer non-conformal contacts with varying proportions of rolling and sliding and has previously been shown to be a more controllable model experiment than utilising the complex geometry of gears. Over the range of tests, the average coefficient of friction results showed that the PA46 + 15% aramid fibres generally had the lowest values compared to the other types of samples; however they generally had the highest steady wear rates, especially at higher loads and velocities. Using a thermal imager to record the temperatures created during the tests it was found that there was always an initial rapid rise in temperature followed by a slow decrease or a plateau, which seemed to follow the friction test results, with temperatures of up to 200 °C being reached. Optical microscopy of the wear surfaces of the PA46 samples showed cracks occurring for low loads and velocities, while at higher loads and velocities melting occurred. The PA46 + aramid fibre samples failed by pitting and large cracks/fractures occurring at the relatively high loads and velocities used. However, they may be suitable for tribological applications under appropriate conditions.
Published Version
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