ELECTROCHEMICAL BEHAVIOUR OF ALUMINIUM IN NaCl SOLUTION - AN IMPEDANCE STUDY.

The polarization resistance (R//p) obtained from impedance measurements of aluminium in 1 M NaCl is studied as a function of surface treatment, solution composition, pH and time of immersion. The variation of R//p is found to parallel the variations of open circuit potential with time of immersion. The R//p is highest for the anodized electrode and least with etched electrode at any time of immersion. It is high in the presence of sodium dodecylsulphate (SDS), and decreases with decrease in pH.