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

摘要

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-S %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-S %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.