Electrochemically Induced Film Formation on CoCrMo Alloy for Hip Implant Application

Abstract: Metal-on-metal (MoM) hip retrievals exhibited the presence of carbonaceous tribofilms, derived from synovial proteins, particularly on the articulating surfaces. Studies suggest that the films decrease corrosion and wear. To extend implant longevity and minimize the side effects due to released metal ions/debris, it is important to investigate the possibility of generating such films artificially on the implant surfaces (before implantation) and evaluate its corrosion resistance in a simulated hip environment. Hence, in this study, a film that mimics tribolayer is generated on CoCrMo alloy surface through electrochemical treatment. The mechanism of formation and corrosion resistance is evaluated by electrochemical impedance spectroscopy (EIS) technique. A standard three-electrode corrosion cell was used to conduct the experiments on polished (R_a < 10.0 nm) CoCrMo alloy disks in bovine calf serum with three different protein concentrations (0, 15, and 30 g/L) and at four different treatment potentials (−0.4, +0.6, +0.7, and +0.8 V). EIS testing (at E_oc, potential amplitude: ±10 mV, frequency range 100 kHz to 0.005 Hz) was conducted pre- and post-potentiostatic treatment. Tribofilm was evaluated by scanning electron microscopy, white light interferometry, and Raman spectroscopy. Results suggest evidence of electrochemically induced film formation and their potential ability to increase the corrosion resistance of biomedical implants. Graphical Abstract: [Figure not available: see fulltext.].