Effect of Structure of Organic Additives on Electrodeposition Behavior of Zn from Alkaline Zincate Solution and Its Crystal Morphology

The effect of structure of organic additives on the electrodeposition behavior of Zn from alkaline zincate solution and its crystal morphology was investigated. Zn was electrodeposited on an Fe electrode at 20-1000 Am(-2), 2.4 x 10(4)Cm(-2), 300 K from unagitated zincate solutions containing the various organic additives as a leveling agent. The suppression effect of additives on the charge transfer and diffusion of ZnO22- ions in Zn electrodeposition corresponded to the number of adsorption site per a straight chain molecule of polymer. The effect of polymer alone on the decrease in size of Zn platelets crystals was small, but the crystal size significantly decreased with coexistence of low molecular additive. The crystal size of deposited Zn decreased in spite of small suppression effect on Zn deposition, showing that the crystal size of deposited Zn doesn't depend on the overpotential for deposition. With coexistence of low molecular additive with polymer, the crystal of deposited Zn was fine regardless of kind of polymer even though Zn deposited at the diffusion control of ZnO22- ions. [doi:10.2320/jinstmet.J2023018]