ROLE OF MINOR ALLOYING ELEMENTS ON THE PERFORMANCE OF LEAD ACID BATTERY GRIDS .2. CORROSION OF LEAD-ARSENIC ALLOYS/

Corrosion of Pb-As alloys (As =0.1, 0.2, 0.3 and 0.4%) in 5.0 M H2SO4 solutions at 30 degrees C was studied under open-circuit, potentiostat ic and galvanostatic polarization conditions. The sulfation process un der open-circuit conditions increased as the As concentration increase d and the open-circuit potential shifted to more cathodic values. The presence of As affected significantly the potentiostatic polarization curve and caused a substantial decrease in passivity current and incre ased the overpotentials of both the O-2- and the H-2-evolution reactio ns. The self-discharging process decreased as the concentration of As increased with formation of substantial amounts of lead oxide beside P bSO4. When Pb-As alloys were subjected to alternative cathodic and ano dic galvanostatic polarization cycles, the corrodable layer thickness increased in the order of: Pb-0.1%As > Pb-0.3%As > Pb-0.4%As > Pb > Pb -0.2%As. The efficiency of PbO2 formation also depended on the percent age As.