ELECTROCHEMICAL-BEHAVIOR OF A ZINC ELECTRODE IN 8M KOH UNDER PULSED POTENTIAL LOADING

Electrodeposition of zinc on zinc plates has been investigated in 8 M KOH. Zincate solutions were obtained by dissolution of ZnO is hot 20 M KOH. Direct current and pulsed current electrodepositions were performed and the deposits observed by SEM. Spongy and dendritic deposits are avoided when using pulsed current technique. A 1:8 to 1:10 ratio for pulse time on rest time is shown to be efficient. The instantaneous current density may be as high as - 1.3 A cm-2 provided the pulse is short enough so that the concentration profile is not too much perturbated. It is shown that a slight dissolution occuring during the rest time is highly accurate in obtaining compact, adherent and well crystallized deposit. Additives such as lead or bismuth induce very small crystallites, and are recommended to improve the compactness. Organic compounds such as fluorinated surfactants are also efficient but the compactness is a little less as above.