| Summary: | Tribocorrosion is a failure phenomenon which involves synergistic effect of electrochemical corrosion and mechanical wear. It usually results into early failure of mechanical components than simple wear and corrosion. Chloride (Cl ^− ) and sulfate ions $\left({{\rm{SO}}}_{4}^{{\rm{2}}-}\right)$ are often found together in corrosive media. In this study, the synergistic effect of Cl ^− and ${{\rm{SO}}}_{4}^{{\rm{2}}-}$ on tribocorrosion of 316L stainless steel was studied by changing the ratio of ${{\rm{SO}}}_{4}^{{\rm{2}}-}$ /Cl ^− in corrosive solution from 0.31 M : 0 to 0 : 0.62 M. The stainless steel was worn against with a ZrO _2 sphere. The coefficient of friction (COF), material loss volume, surface micro-topographies and surface chemical composition in different solutions were compared to explore the synergism between ${{\rm{SO}}}_{4}^{{\rm{2}}-}$ and Cl ^− . The results indicated that the mix of Cl ^− and ${{\rm{SO}}}_{4}^{{\rm{2}}-}$ reduced material loss volume by a quarter when compared with that in pure Na _2 SO _4 or NaCl solution. More than half of material loss was caused by the synergism between wear and corrosion in mixing solutions. The synergistic effect between ${{\rm{SO}}}_{4}^{{\rm{2}}-}$ and Cl ^− could promote the transmission of metal into oxides. This had two effects on tribocorrosion. First, the existence of oxides would cause abrasion which accelerated wear-affected corrosion and enhanced mechanical wear (corrosion-affected wear). On the other side, the transmission of metal into oxides benefited for the formation of tribo-film. The flexible stainless steel needed to coordinate deformation with the tribo-film which had relatively low deformability. This aggravated deformation of stainless steel and promoted surface work-hardening effect. It was helpful for stainless steel to resist wear, thus, the corrosion-affected wear was decreased.
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