Cobalt in gold electrodeposits

Abstract

SummaryOne of the most widely used gold electrolytes for sliding wear and electrical contact application is the acid gold cyanide solution containing a cobalt salt. Several authors have indicated the cobalt is incorporated in two different forms: — metallic cobalt, substitutionally dissolved in the gold and— a complexed cobalt, included in the deposit.This paper describes an analytical method to differentiate between the two forms. It consists of the application of dc or pulse voltammetry after prior adsorption of the cobalt(II) dimethylglyoxime chelate at the hanging mercury dropping electrode.The amount of both Co compounds is determined in relation to different Co solution concentrations and current densities. It is shown that the metallic and complexed Co content in the gold deposit is closely related to the durability and contact resistance.