Electrochemical corrosion behaviour of dental/implant alloys in saline medium

Dental alloys implanted in mouth are exposed to various aggressive conditions. Keeping this in view, corrosion behaviour of various dental alloys viz. Ni–Cr, Co–Cr, Cu–Ni–Al and commercially pure Ti (c.p. Ti) were studied in 3% NaCl medium by using Tafel polarization, cyclic polarization and electrochemical impedance spectroscopy techniques. EIS studies were carried out for different duration viz. 1 h, 1 day and 7 days to evaluate the stability of passive film and change in corrosion characteristics with time. It has been found that for Ni–Cr, Co–Cr (DRDO developed) and c.p. Ti the passive film characteristic changed with time whereas for Co–Cr (commercial) and Cu–Ni–Al alloys, the passive film characteristics remained same. From DC electrochemical studies various parameters viz. i corr , E corr , i pass , E pass were evaluated. The corrosion rates were observed to be in the order Cu–Ni–Al > Co–Cr (commercial) > Ni–Cr > c.p. Ti > Co–Cr (DRDO).