A metallic biomaterial tribocorrosion model linking fretting mechanics, currents, and potentials: Model development and experimental comparison

Mechanically assisted crevice corrosion may disrupt passive oxide films on medical alloys and lead to rapid repassivation reactions which generate corrosion currents and shifts in electrode potential due to the non-equilibrium nature of the reactions and the transient unbalancing of anodic and cathodic reactions. This study presents a theoretical approach to predict currents and voltages over time utilizing the concepts of heredity integrals, area-dependent surface impedance, contact mechanics and the high field physics of oxide repassivation. Two heredity integrals are presented relating, first, the sliding mechanics and oxide film repassivation physics to the current, and second, relating the electrode potential to the current using impedance concepts. Current-potential-time responses to controlled fretting conditions were measured across a fretting frequency from 0.2 to 10 Hz and compared to theoretical results. The coupled integrals were shown to predict the overall current-potential-time behavior for CoCrMo alloy surfaces under several controlled fretting corrosion conditions (loads, sliding speeds, etc.) with a high degree of similarity. These models can be adapted to numerical analyses of tribocorrosion to predict performance.