CORROSION BY ALTERNATING-CURRENT - STUDY OF THE ANODIC POLARIZATION OF MILD-STEEL IN NA2SO4 SOLUTION

A study was made of the anodic polarization of mild steel in Na//2SO//4 solutions (pH 3-9) in the presence of a sinusoidal electric current. The measurement was carried out over a range of alternating current (AC) densities form 0 to 200 mA/cm**2 and AC frequencies from 20 to 6000 Hz. It was found that the corrosion potential of mild steel shifted toward the active direction in the presence of AC. AC also increased the passivity current density in a way similar to the addition of chloride ions to the electrolyte. The phenomenon was explained with a time-averaging analysis of the mixed potential theory.