CHARACTERIZATION OF ANODIC FILMS ON LEAD AND LEAD ALLOYS BY IMPEDANCE SPECTROSCOPY

The behaviour of lead and lead-antimony binary alloys with 1.3-4.5 wt.% antimony was investigated in the lead sulfate and lead oxide potential regions by means of cyclic voltammetry and electrochemical impedance spectroscopy. The impedance data show that the inner PbO barrier layer is formed beneath the initially grown PbSO4 porous layer at potentials positive to -0.2 V versus SCE. The antimony content influences the characteristics of the anodic layer by decreasing its resistance and increasing its capacity. These changes were observed both on the lead sulfate and especially the lead oxide layers. With increased anodic polarization, the film resistance increases as well while the capacity shows the opposite change.