ELECTROCHEMICAL STUDIES OF LASER-TREATED CO-CR-MO ALLOY IN A SIMULATED PHYSIOLOGICAL SOLUTION

The aims of this work were to study the crevice corrosion resistance o f laser-treated Co-Cr-Mo alloy by electrochemical techniques and to ch aracterize the electronic properties of the passivating films. Open-ci rcuit experiments and cyclic polarizations with crevice-free samples h ave been carried out as well as electrochemical impedance spectra usin g Bode-Nyquist and Mott-Schottky techniques. Scanning electron microsc opy (SEM) and Xray photoelectron spectroscopy (XPS) analysis have been used in order to evaluate surface modifications. It has been observed that laser-treated Co-Cr-Mo alloy shows good corrosion resistance in spite of some degradation at the dendrites formed during treatment. By XPS it was found that at 6-9 nm depth there exists an enrichment in o xygen and a decrease of Or which could have a slight effect on the cor rosion resistance and it was seen that the film is mostly formed by Cr 2O3. Mott-Schottky plots show that a possible transition from n-type t o p-type semiconductivity may have occurred.