Impact of counterface topography on the formation mechanisms of nanostructured tribofilm of PEEK hybrid nanocomposites

•Counterface topography influences formation of the tribofilms of PEEK composites.•A close relationship between structure and property of the tribofilms was revealed.•A nanostructured tribofilm benefits best the tribological performance.

The effect of steel counterface topography on the formation mechanisms of nanostructured tribofilms of polyetheretherketone (PEEK) hybrid nanocomposites was studied. Three types of surface finishes with mean roughness Ra ranging from nano- to micro-scale were investigated. Tribo-sintering of nanoparticles, oxidation of counterface steel and compaction of wear debris are identified to be competing factors dominating the formation and function of the tribofilms. Counterface topography played an important role on the competing factors, and thereby influenced significantly the final structure, the load-carrying capability and the lubrication performance of the tribofilms. It was disclosed that a thin tribofilm, which mainly consists of silica nanoparticles and which forms on the counterface with a sub-micron roughness, benefits best the tribological performance of the composites.