A comparative investigation of the wear behavior of PTFE and PI under dry sliding and simulated sand-dust conditions

The wear behavior of polytetrafluoroethylene (PTFE) and polyimide (PI) has been comparatively evaluated under dry sliding and simulated sand-dust conditions. An improved block-on-ring wear tester equipped with an attachment for simulating the sand-dust environment was used to evaluate the abrasive wear behavior of materials. The sand collected from the Yellow River of China was used to simulate the sand-dust environment, also different loads and sand-dust sizes were chosen for tribological tests. The two chosen polymers showed different wear behavior under sand-dust conditions and the wear rates of PTFE were much lower under sand-dust conditions than under dry sliding conditions. This was attributed to the formation of the tribolayer on the worn surfaces during the abrasive wear process. The sand-dust enhanced the wear resistance of PTFE, but reduced that of PI because, in contrast to PTFE, there was no tribolayer formed on the PI worn surface. The wear rate of PTFE increased under sand-dust conditions while the wear rate of PI decreased with the increase of applied load. The higher hardness of PI and fragmentation of abrasive particles under high loads accounted for the decrease in wear rate as load increased.