Influence of inflammatory environment on the fretting corrosion of CoCrMo–Ti6Al4V alloy pairs at the hip head–neck interface

Implantation of artificial hip joints frequently induces local inflammatory responses, resulting in the accumulation of reactive oxygen species (ROS) such as H₂O₂ in peri-prosthetic fluid. These species critically affect fretting corrosion at the femoral head–neck interface. In this study, the fretting corrosion behavior of a CoCrMo–Ti6Al4V alloy pair was examined under simulated inflammatory conditions by introducing H₂O₂. A running condition fretting map (RCFM) was established, identifying three fretting regimes: partial slip (PSR), mixed fretting (MFR), and gross slip (GSR). Compared with normal physiological conditions, the presence of H₂O₂ markedly accelerated corrosion and aggravated material degradation across all regimes. The damage mechanisms of the Ti6Al4V–CoCrMo pair vary significantly across different regimes: abrasive wear and tribocorrosion dominate in PSR; adhesive wear and intensified tribocorrosion occur in MFR; and in GSR, severe abrasive wear, tribocorrosion were observed. Increasing H₂O₂ concentration enhanced thermodynamic stability but intensified corrosion kinetics. Concurrently, the dominant damage mechanism transitions from abrasive wear to tribocorrosion characterized by spallation. These collectively lead to a marked increase in material loss and metal ion release. Overall, H₂O₂ promotes cathodic depolarization and the formation of mechanically unstable oxide films, thereby strengthening corrosion-wear synergy and exacerbating material damage under inflammatory conditions.