Formation and function mechanisms of nanostructured tribofilms of epoxy-based hybrid nanocomposites

The nanostructures and properties of the tribofilms of epoxy (EP) composites filled with short carbon fibers (SCF) and different volume fractions of monodisperse silica nanoparticles were investigated. When the conventional composite filled only with SCF was considered under a high pv condition, an iron oxide layer is formed on the steel counterface. The addition of even only 0.05 vol% nano-silica leads to a significant change of the tribofilm's structure and the tribological behavior of the composite. With increasing silica content, the oxidation layer on the steel surface is gradually replaced by a silica-based tribofilm. A close relationship between the tribofilms' structure and the tribological behavior of the composites was identified. Mixing, possible reactions and tribo-sintering of silica nanoparticles with other wear products are deemed to be main mechanisms inducing the formation and the lubricity of the silica-based tribofilm.