Changes in the properties of a citrate electrolyte used to manufacture cobalt-tungsten coatings

The study of the electro conductivity of a citrate solution that contains cobalt sulfate (0.2 M) and sodium wolframate (0.2 M) used to obtain cobalt-tungsten coatings is carried out. A significant decrease in the conductivity in time of this solution as compared to aqueous and citrate complexes of cobalt was registered. It was shown that the observed changes occurred due to the generation of a mixed heteronuclear complex (probably polymeric) in the solution. The fractioning of the solution by gel filtration showed that all the changes resulted from the conversion of the substance with a high molecular weight. (authors)