How Insoluble Anodes are Used in Zinc Electroplating?

How Insoluble Anodes are Used in Zinc Electroplating?

Electroplated nickel is used extensively to enhance the utility, value, and sales appeal of consumer goods and manufactured products. Other nickel coatings are used to improve physical properties such as wear resistance, heat resistance, or corrosion resistance. In many important applications, the nickel coatings serve the dual role of providing a bright decorative coating and imparting improved corrosion resistance or other functional properties.

Insoluble anodes are used for specific purposes where nickel anodes would not be practical. Applications include anodes for the internal plating of tubes, and as auxiliary anodes for plating into deep recesses. A further situation where insoluble anodes might be selected is when there is the limited spacing between the components being plated (e.g. some electronic applications). Insoluble anodes are commonly fabricated from platinized titanium, although other inert conductive materials such as graphite can be used.

When insoluble anodes are used, the pH of the solution in the vicinity of the anodes will fall due to the liberation of hydrogen ions from the oxidation of water at the anode surface. At the same time, oxygen and/or chlorine will be released. These can oxidize some organic additives in the solution. Chlorine can also lead to health concerns. These effects become significant when more than 20% of the total bath current passes through insoluble anodes.