Effect of NaCl Concentration on Galvanic Corrosion Behavior of Zinc and A1050 Couples

Abstract

In this study, effects of NaCl concentration on galvanic corrosion behavior of zinc and A1050 couple was investigated by means of corrosion potential and galvanic current measurements, surface observation, electrochemical impedance measurements, and polarization tests. Corrosion potential and galvanic currents were measured for 72 hours during immersion in 0.01 to 2 mol L−1 NaCl solutions. During the galvanic corrosion tests, the corrosion potential of the couples remained nearly constant, except in the early stage of immersion, and became more negative as the NaCl concentration increased. During the immersion test, the galvanic current always flowed in the direction of the zinc being the anode. However, the galvanic current changed with immersion time. That is, in the early stage of immersion, the galvanic currents were higher at higher NaCl concentrations, but over time, these values decreased, and after 72 hours, they decreased to much lower values and were almost independent of the NaCl concentration. Surface observations, electrochemical impedance measurements, and polarization curve measurements revealed that a decrease in the cathodic reaction rate on the A1050 surface with immersion time. Finally, the corrosion mechanisms that explain the galvanic corrosion of zinc and A1050 were discussed.

Keywords

• galvanic current
• couple potential
• zn/al
• oxygen reduction reaction