Abstract

The corrosion behavior of Cu-Fe and Cu-Fe-Al was studied in NaCl solutions without and with different concentrations of some inorganic additives, Na₂MoO₄, K₂Cr₂O₇, and KIO₃. The measuring techniques used were, open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The potentiodynamic polarization measurements indicated that the corrosion current, I_corr, o;f Cu–Fe is less than that of Cu–Fe–Al. The investigated additives in 3.5% NaCl shift corrosion potential Ecorr to more positive values (except in K₂Cr₂O₇ reverses the action for Cu-Fe alloy) and increase Icorr. Impedance measurements indicated that Nyquist plots for Cu–Fe and Cu–Fe–Al may be regarded as part of semicircle (arc), the values of R_p for Cu–Fe are higher than those for Cu–Fe–Al except in K₂Cr₂O₇. On the other hand, the values of C_dl for Cu–Fe are lower than those obtained for Cu–Fe–Al. The presence of these additives in NaCl solutions increases the values of polarization resistance (R_p) and decreases the values of (C_dl).

Key words: Copper alloys, corrosion, passivators, NaCl.