Abstract: The formation of a tribo-film on the counterface plays an important role on the tribological performances of polymer subjected to mixed and boundary lubrication conditions. However, when freshwater is used as a lubricant, the formation of a tribo-film usually is hindered. In order to overcome this disadvantage, PEEK/alpha-FeOOH nanocomposites were developed and their tribological performances were studied under water lubrication conditions in the present work. It was demonstrated that the inclusion of alpha-FeOOH nanoparticles (NPs) into the PEEK matrix improves significantly the tribological performance of the matrix. The nanostructures and properties of the tribo-films formed on the steel counterface were comprehensively studied. It was identified that the addition of alpha-FeOOH NPs promotes the formation of a lubricating tribo-film which covers the entire counterface. Based on the investigations on tribo-films, we deem that the alpha-FeOOH NPs act as precursors for the dehydration reaction promoting the formation of a tribo-film which consists of alpha-Fe2O3 and transferred PEEK. It is assumed that the enhanced tribological performance is related to the possibly high load-bearing capability and "easy-to-shear" characteristic of the tribo-film. 

KeyWords Plus: FILLED PPS COMPOSITES; ETHER-KETONE PEEK; MECHANICAL-PROPERTIES; BOUNDARY LUBRICATION; POLYMER COMPOSITES; SLIDING CONTACTS; CARBON-FIBERS; WEAR; FRICTION; BEHAVIOR 

Published in RSC ADVANCES, 6 (56):51247-51256; 10.1039/c6ra06904e 2016