Corrosion behaviour of titanium in biofluids containing H2O2 studied by electrochemical impedance spectroscopy

This work aims at studying the electrochemical behaviour of titanium in the presence of an artificial biofluid containing H2O2, mimicing the situation , where the metal is implanted in the human body and hydrogen peroxide is g enerated by an inflammatory reaction. A phosphate buffered saline (PBS) sol ution and two PBS/H2O2 solutions containing 50 and 150 mM of H2O2 were used to simulate the body fluids. The behaviour of the metal was monitored as a function of time by electrochemical impedance spectroscopy (EIS) for three weeks. After one week, the PBS/H2O2 solutions were replaced by fresh PBS s olutions in order to simulate the end of the inflammatory process and recov ery of the system. All the experiments were carried out at a constant tempe rature of 37 degreesC. From the simulation of the experimental EIS spectra, it was concluded that the corrosion resistance of titanium is strongly aff ected by the presence of H2O2 and when the peroxide is removed, the metal d isplays a sharp resistance increase. Furthermore, the oxides formed in H2O2 are rougher and display higher ionic conductivities than the oxides Formed in the absence of peroxide. The study was complemented with potentiostatic experiments and scanning electron microscopy observation of the metal surf aces. (C) 2001 Elsevier Science Ltd. All lights reserved.