Electrochemical Studies on the Passivation Behavior of Cu-Ni-Fe Alloy in Borate Buffer Solution at pH 8.4
Cu-Ni-Fe alloy-layer was prepared by the method of copper oxide- nickel oxide mixed powder deposited on the surface of mild steel samples and then treated under high temperature and hydrogen gas atmosphere. Polarization techniques and Mott-Schottky analysis in conjunction with the point defect model (PDM) have been used to investigate the semiconductor properties of the passive films formed on the surface of Cu-Ni-Fe alloy layer in borate buffer solution at pH 8.4. The results showed that the passive film formed on the surface was more compact, highly protective with higher heating temperature. Carriers density and vacancies diffusion coefficient of the passive film formed on Cu-Ni-Fe alloys decreased with higher heating temperature. The vacancies diffusivity is about magnitude of 10-20m2•s-1 in borate buffer solution at pH 8.4.