Modelling the repassivation kinetics of CoCrMo alloys in simulated body fluids

• CoCrMo alloys used for biomedical applications are often exposed to the combined effect of mechanical wear and electrochemical corrosion. Tribocorrosion tests have been performed in this work to investigate the repassivation kinetics of a HC CoCrMo alloy in four different solutions commonly used to simulate body fluids. The repassivation kinetics are analysed by fitting two different exponential equations. The comparison of the different equations reveals that that a second order exponential equation models the repassivation currents more closely than a first order exponential equation. A repassivation model based on a second order exponential equation is suggested. The repassivation currents are divided in two main phases, a ’coverage’ phase and a ’film thickening’ phase. At the initial stage, when part of the surface is exposed to the corrosive media, higher potentials lead to faster repassivation rates. By contrast, potential does not have a clear effect at the thickening phase, when the material is protected by the oxide film formed on top of the surface.Conclusions The repassivation kinetics of a CoCrMo alloy have been investigated.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Korrosionsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Corrosion Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Tribologi (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Tribology (hsv//eng)

Nyckelord

joint replacement

corrosion

biomedical application

Implant wear

Machine Elements

Maskinelement

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