[Some aspects concerning the electrochemical corrosion of the Gaudent-S dental alloy].

The potentiodynamic polarization methods have been employed to evaluate the corrosion resistance of the Gaudent-S dental alloy in a slightly acid artificial saliva (Fusayama's saliva; pH = 6.18), a slightly alkaline artificial saliva (Rondelli's saliva; pH = 7.75) and in an acid saline solution (NaCl/lactic acid; pH = 2.64). The results were compared with those obtained for copper and aluminium--the principal components of the studied alloy. In Fusayama's artificial saliva both the copper and Gaudent alloy exhibit close indentic cyclic voltammograms, typical for pitting corrosion; the pitting potentials being 1550 mV (SCE) for Gaudent-S and 1350 mV (SCE) for copper, while the repassivation potential is 700 mV (SCE), the same for the two analysed metals. In the Rondelli's artificial saliva and in acidic saline solution the passivation domain is considerable reduced; the corrosion potential and the repassivation potential coincides. In the saline acid solution the current densities are two times higher than those obtained in the other two solutions. In the aluminium case it can be noticed that the passivation domain is very reduced, no cathodic peak is observed and much more current densities are registered in the positive potential domain.