Factors influencing the preferential orientations in zinc coatings electrodeposited from chloride baths

Abstract

The influence of factors affecting the texture formation in zinc coatings electrodeposited from weakly acid zinc baths has been investigated, particularly those of cathodic current density, electrolyte additives and substrate texture type. Deposits showing no preferential orientations were obtained from a chloride bath with no primary inhibitors, with which the earlier theory on autoinhibition caused by colloidal zinc hydroxide in sulphate electrolytes was confirmed. The addition of synthetic inhibitors resulted in the production of various types of texture according to the electrolysis conditions and substrate texture type. Cone fibre texture coatings were obtained on cold worked copper cathodes and at lower cathode densities. A simple fibre texture was produced only at higherD _c values. The preferential orientation of electrodeposited zinc coatings on electrolytic nickel textured substrates depended on whether the electrochemical conditions or the textured substrate was the dominant factor. Various simple fibre textures were formed on electrodeposited amorphous Ni−P alloy substrates irrespective of the electrochemical conditions. Within a relatively short time after the completion of the electrodeposition of zinc coatings from chloride or sulphate baths, recrystallization processes were observed at room temperature.