A study of the corrosion of negative-plate lead-antimony lugs in lead/acid batteries

Corrosion of the negative-plate lug of a lead/acid battery has been investigated by means of metallographic examination, electron microprobe and chemical analysis, and electrochemical techniques. The results show that both the metallographic texture of the alloy and the distribution of antimony in the alloy play an important role in the corrosion process. Since, for large lugs, the chilling rate after casting varies at different locations, the crystallines in the central part of the lug are more disordered and smaller in size than those in the edge regions. The content of antimony in the surface layer of the central part is higher than that at the edge. Depolarization of oxygen dissolving in the electrolyte causes both the antimony and the lead in the alloy to become corroded. The uneven distribution of antimony and its surface segregation serve to accelerate the corrosion of the central part of the plate lug.