Abstract
The overvoltage of lead anode was studied in relation to the electrolytic corrosion of buried cable sheath. At the current densities 1∼1000 μA/cm2, the overvoltages were measured in 0.1 N sodium sulphate solutions, then the step-wise potential rise and the increase of resistance polarization at lower potential were observed a linear relation between overvoltage and log-current density was not observed, but in the case of the experiment with an electrode covered with lead peroxide, prepared by electrolysis in high current density, a linear relation was obtained. The total charges carried through unit area of anode was nearly constant for each arrest of potentials. The films of first arrest were highly resistive, and their thickness was about 1100 Å for low current densities. The second arrest corresponded to the growth of very low resistive films of lead peroxide, and oxygen evolved steadily at the third arrest. For high current densities, the total thickness of films was about 1400 Å.
