Impedance characteristics of carbon steel under cathodic protection

The potential dependence of the faradaic impedance of carbon steels in 3.5% NaCl solution was measured by ac impedance technique. The polarization resistance, and also the cathodic protection efficiency obtained from weight loss, maximized at 0.70 V with respect to saturated Ag/AgCl electrode . Consequently, the potential at faradaic impedance maximum corresponds well to the optimum cathodic protection potential. The study asults showed that the ac impedance technique is a promising method for monitoring and determining the optimum cathodic protection potential.