Nickel electrocrystallization: Influence of unsaturated organic additives on the mechanism of oriented crystal growth
(EN)
Vouros, D
(EN)
Macheras, J
(EN)
Spyrellis, N
(EN)
Kollia, C
(EN)
The addition of organic compounds to the electrolytic baths during the electrodeposition of metals affects the structure and the properties of the deposits, leading to the preparation of coatings with defined characteristics. In this work, a complete study of the action of the organic additives on the crystalline orientation of the nickel electrodeposits was carried out. The selection of the organic compounds was made in order to investigate the effect of the stereochemical structure and unsaturated bonds on the nickel electrocrystallization process. It was found that the presence of acetylenic compounds (butyne-2-diol 1,4 and propyne-2-ol) in nickel plating baths leads to the predominance of high inhibited modes of crystal growth. Propyne-2-ol seems to be more active, as the geometry of its molecule favours the adsorption of the additive on the metallic surface and, thus, its faster hydrogenation. With the additon of phenyl propyl alcohol, a strong perturbation of the oriented crystal growth of the nickel crystallites occurs. The adsorption of the phenyl group on the metallic surface and its hydrogenation is responsible for the predominance of high inhibited textures. In the case of coumarin, the complexity of its molecule makes its adsorption more difficult, resulting in the development of [100] textured deposits even at high concentrations of the additive. Finally, when sodium benzene sulphonate or saccharin are added to the bath, the presence of sulphur in their molecules influences the nickel electrodeposition process through a different mechanism.
(EN)
