Effect of the Polarization Regime on the Structure of Zinc Dendritic Deposits

Abstract

The influence of polarization regime on growth dynamics and structure of electrolytic dendritic zinc deposits obtained at room temperature from electrolyte with 0.3 mol/l zinc oxide and 4 mole/l sodium hydroxide is studied. The electrodeposition has been performed at constant current and constant potential as well as in pulsed regimes. The technique of chronopotentiometry at constant current has been used for the determination of the surface area of dendritic deposits in situ. The zinc microstructure has been studied with the help of electron microscopy. The surface of the deposits obtained in pulsed current regime intensively increased during the first 5 min of electrolysis and afterwards it changed insignificantly. In conditions ofpotentiostatic electrolysis, the coefficient K, which features the ratio of dendritic deposit surface to the base square, increased with time linearly; in pulsed potential regime, it increased according to power dependence. The deposits obtained under potentiostatic regimes show the lowest overall density with minimal changes along the deposit thickness. The density of the deposits, which crystallized under pulsed current regime, shortly increased upon completion of active dendrite extension.