KINETICS AND MECHANISM OF PBSO4 ELECTROFORMATION ON PB ELECTRODES IN H2SO4 AQUEOUS-SOLUTIONS

The electrochemical processes related to the passivation of Pb in 5 M H2SO4 at 25-degrees-C, have been investigated combining a rotating rin g-disk electrode, linear potential sweep voltammetry and potentiostati c pulse techniques complemented with scanning electron microscopic ima ging. The kinetics of PbSO4 anodic layer growth can be explained throu gh the initial formation of a barrier layer acting as an ionic conduct or, and the transference of Pb2+ cations from the substrate through th e conducting layer yielding Pb2+ ion in the solution. These ions furth er contribute to passivation through the precipitation of a PbSO4 pass ivating layer.