Electrochemical Behaviour of Pure Aluminium and Al–5%Zn Alloy in 3% NaCl Solution

Abstract

The effects of both immersion time and temperature were investigated to examine the electrochemical anode characters of pure aluminium and Al–5%Zn in 3% NaCl solution. Open circuit potential (OCP), linear polarization resistance (R p), potentiodynamic polarization, electrochemical impedance spectroscopy techniques and Evans diagrams were used to characterize the electrochemical behaviour of the studied pure aluminium and Al–5%Zn alloy. The materials surface was observed by means of scanning electron microscope. Whatever the studied temperature and the immersion time are, the Al–5%Zn alloy induced a considerable activation compared to pure aluminium by shifting the OCP toward the negative direction and by a significant increase of the anodic current densities. Arrhenius relation between corrosion current densities and the inverse of temperature shows that the anodic oxidation of the Al–5%Zn alloy is more spontaneous than that of pure Al. The Al–5%Zn alloy coupled to the carbon steel leads to a better protection than the pure aluminium.