Characterization of passive films on brass in slightly alkaline solutions

R. PROCACCINI; M. VAZQUEZ; S. CERÉ

Banff - Canadá

Congreso; 58th Meeting of the International Society of Electrochemistry; 2007

ISE

The corrosion resistance of Cu alloys, particularly Cu-Zn alloys, strongly depends on the quality of their protective passive film. This study focuses on the influence of Zn as alloying element in the improvement of the corrosion resistance of copper-base alloys, using boric-borate buffer (pH = 7.8) as electrolyte. Particularly, the key parameters characterising the kinetics of the oxygen reduction reaction are investigated. Also, the detrimental effect of the presence of chloride ions in the electrolyte is being evaluated. The film growth and the composition of the passive layer are evaluated using conventional electrochemical techniques, such as polarization curves, cyclic voltammetry and EIS and complemented spectrophotometrically, using reflectance spectroscopy. As expected, the presence of chloride ions in solution modifies the composition of the film and lowers the charge transfer resistance. The shape of the cathodic polarization curves is also affected, particularly in the mixed (activated and diffusional) controlled range.