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Turkish Journal of Chemistry

Abstract

A study of the electrodeposition of silver from 2 different types of electrolytes; (1) neutral pyrophosphatecyanide electrolyte and (2) alkaline high concentrated cyanide electrolyte in the presence of a variety of additives such as 2-mercaptobenzothiazole, potassium selenocyanate, and potassium antimony tartrate was performed. Influence of additives and cyanide concentration on microstructure and kinetics of the cathodic processes were studied. A brightener couple, 2-mercaptobenzothiazole and potassium antimony tartrate, were combined within this investigation anddetectedtobehighlyeffectiveforsilverelectrodeposition. Therapidincreaseincurrentdensityatthesamepotential interval related to grain refinement effect of potassium antimony tartrate was shown. The cyclic organic compound, 2mercaptobenzothiazole, polarizes the reduction to high cathodic potential in pyrophosphate electrolyte. However, the sufficient levelling effect required for the mirror-bright appearance seems to be related to the high polarizing effect of the high concentration cyanide content. In the case of pyrophosphate electrolytes, sufficient levelling cannot be achieved, so semigloss coatings are obtained. The low cathodic potential electrodeposition of silver in pyrophosphate electrolyte, which is found to proceed by 3D instantaneous nucleation, is polarized to high cathodic potentials and grows into 3D progressive nucleation and diffusion-controlled growth in high concentration cyanide electrolyte.

DOI

10.3906/kim-1907-80

Keywords

Electrodeposition, silver, cyanide, brighteners, potassium antimony tartrate, 2-mercaptobenzothiazole

First Page

378

Last Page

392

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