The effect of simulated inflammatory conditions and Fenton chemistry on the electrochemistry of CoCrMo alloy

Inflamed conditions may develop in total joint replacement applications and may impact on the corrosion of metallic biomaterials like CoCrMo alloy. The influence of simulated inflammatory (SI) conditions on the corrosion behavior of CoCrMo alloy was investigated. A range of SI solutions, based on phosphate buffered saline with H2O2, HCl, and Fe3+additions, were investigated. Open circuit potential (OCP), corrosion currents and impedance of the oxide film surface were all significantly (p < 0.05) affected by increases in H2O2concentration and decrease of pH. OCP (vs. Ag/AgCl) increased from −0.250 V in PBS solution to 0.355 V and 0.650 V in 30 mMH2O2at pH 7.4 and pH 1 PBS solution. Iron ions (0.1 mM) in PBS solutions with 10 mMH2O2(Fenton chemistry) increased OCP to 0.6 V.Icorrincreased from 0.2 µA/cm2to 14 µA/cm2in SI conditions. Electrochemical impedance spectroscopy showed decreased in oxide resistance (Rox,p < 0.05) while capacitance (CPE) increased (p < 0.05) in SI solutions, pH 7.4 (Rox = 5 × 103Ω cm2, CPE = 55 µF/cm2) as well as in Fenton reagent solution (Rox = 3.2 × 104Ω cm2, CPE = 45 µF/cm2) compared to PBS only (Rox = 5 × 105Ω cm2, CPE = 31 µF/cm2). These results indicate the corrosion susceptibility of CoCrMo alloy can be significantly increased by SI solutions, increasing the oxidizing power and decreasing the passivity of the oxide film. Cell‐released chemicals such as H2O2and acid are able to facilitate the corrosion of CoCrMo alloy and demonstrate part of the mechanism of inflammatory cell induced corrosion.