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The influence of sorbitol or glycerol polyalcohols on the electrodeposition of zinc and on morphology of the zinc film is discussed. The deposition current efficiency, in the potential range -1.30 V to -2.50 V, was *90% in all baths. Increasing the sorbitol concentration in the bath shifted the deposition to more negative potentials, *50 mV, and decreased the current density (j p ) of the zinc deposition significantly. On the other hand, adding glycerol did not significantly affect either j or the deposition potential of zinc. Scanning electron microscopy (SEM) showed that either sorbitol or glycerol lead to the formation of granular deposits. The best zinc morphology was obtained with 0.52 M sorbitol or glycerol in the plating bath. The presence of sorbitol or glycerol in the plating bath was beneficial, since the resulting zinc deposits were compact and without holes.

The influence of sorbitol or glycerol on the electrodeposition of ZnNi alloys and on the morphology, composition and structure of the ZnNi deposits was investigated. The highest current efficiency (CE), around 90%, was obtained in the presence of glycerol in the potential range from approximately −1.30 V to −1.40 V, while in the presence of sorbitol or absence of either polyalcohol the CE was 82-85%, for the same potential range. Scanning electron microscopy (SEM) analysis showed that ZnNi deposition at −1.26 V or −1.40 V from a bath with sorbitol led to the formation of more compact deposits than with glycerol. Energy dispersive X-ray spectroscopy (EDS) analysis showed that the Ni content in the deposit obtained in the presence of sorbitol remained in the range of 7-9.5 wt% Ni, over a large range of deposition conditions. On the other hand, ZnNi deposits with variable Ni content (5.5-19.5 wt% Ni) were obtained from baths with glycerol or without either polyalcohol, by shifting the deposition potential. All ZnNi deposits showed uniform distribution of the elements Zn and Ni. X-ray analysis of ZnNi deposits obtained from plating baths with and without polyalcohol's at −1.26 and −1.40 V presented the γ, γ 1 and Pt 3 -Zn phases.

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A boric acid bath for ZnNi alloy electrodeposition was developed with mannitol as additive. The deposition process was investigated by cyclic voltammetry. It was found that the current density decreased, due to adsorption of a boric-mannitol complex and/or changes in the morphology, but the initial deposition potential was not affected. At deposition potentials more negative than -1.20 V, the current efficiency obtained was high (80-85%) in all baths studied. The addition of mannitol to the bath led to the formation of the best ZnNi deposits, composed of coalesced globular grains smaller than *1 lm in diameter. Also, all of the ZnNi deposits studied consisted of c, c 1 , and Pt 3 Zn phases. The Ni content in the ZnNi deposits produced in the presence of mannitol increased from 6 to 10 wt% only in the range -1.26 to -1.40 V. It is suggested that the ZnNi deposits produced in these baths probably offer sacrificial protection to the substrate.