Electrocrystallisation of Zinc from Ammonium Chloride Solution in the Presence of an Additive

摘要

Zinc electrocrystallisation, in presence of a commercial additive used in zinc plating, was used t determine the mechanism by which the additive acts. Before studying zinc electrocrystallisation, the mechanism of hydrogen evolution from a zinc-free solution with or without additive was studied in order to determine the electrode coverage by the additive. The zinc deposition process can be summarised as (i) hydrogen evolution on the bare steel substrate, rapidly stopped by a zinc underpotential deposition; (ii) a first zinc layer deposition without any influence of the additive, in the free holes of the adsorbed layer; (iii) zinc deposition under the influence of the additive.