IN-SITU SPECTRO-ELECTROCHEMICAL STUDIES ON THE OXIDATION MECHANISM OF BRASS

The oxidation mechanism of brass has been studied with in-situ spectro-electrochemical techniques. The results indicate that the brass corrosion mechanism may be interpreted as being composed of dissolution chemistries of zinc and copper, except that the oxidation potential of zinc in brass is more positive than that of pure zinc. After zinc is oxidized, copper oxidizes to Cu(I) hydroxide/oxide in two consecutive steps, followed by further oxidation to Cu(II) hydroxide/oxide. These hydroxides/oxides are reduced upon cathodic scanning of the potential to produce the brass surface in reverse sequence as for oxidation; a relatively large amount of the zincate ion and a small amount of copper (II) hydroxide are still on the electrode surface, even after a long period of reduction at -1.3 V vs the Ag/AgCl, saturated KCl reference electrode.