Platinum Plated Titanium Anodes for Electroplating in Acidic Copper Sulphate Solution

Jun 08, 2021

Platinum Plated Titanium Anodes for Electroplating in Acidic Copper Sulphate Solution

For a couple of years, gold-plating baths have been equipped with undissolvable anodes. Significant reasons for using undissolvable anodes are to avoid pollutions of the gold-plating bath by other metals from the gold anodes and to keep the current output at the anode and cathode possibly on the same level. Depending on the type of gold-plating bath you can use undissolvable anodes of stainless steel, graphite, nickel/ chromium alloys, or platinum.

The most significant anode materials for chromium-plating baths are lead and lead alloys. But those lead anodes have two big disadvantages: firstly, the passive skin developing on lead anodes suspended in the bath without any current supply; secondly, the formation of lead chromate entailing pollution of the bath. Platinum-plated titanium anodes have proved suitable above all in automatic chromium-plating equipment for rotogravure cylinders, where it replaces the conventional lead anodes. Uniform and smooth coatings are obtained without necessitating repetitive filtering of the bath.

Also, the acidic copper sulphate bath is of great importance for the application of platinum-plated titanium anodes. Acidic copper sulphate baths are chiefly used for applying thick copper coatings. The plating baths mainly consist of copper sulphate, sulphuric acid, and certain additions. In the course of time, the acidic copper sulphate baths are enriched with copper sulphate because the copper is partly dissolved in a monovalent form at the copper anode and oxidized in the open air. In order to prevent such an enrichment, a part of the copper anodes is replaced by undissolvable anodes of platinum-plated titanium.

The automobile industry inserts platinum-plated titanium anodes in acidic activation baths, e.g. in advance to nickel-plating; platinum-plated titanium hooks are used during electropolishing of small workpieces for suspension hooks in aggressive electrolytes.

Platinum plated titanium is a well-known anode material for electroplating. The shape may be wire, bars, sheets,s or expanded metal of titanium. Additional power supplies from titanium-coated copper bars can be used for very high loads and uniform current distribution. The platinum coating is applied either by electroplating, by thermic or vacuum-technological processes. While platinum is decomposed in the course of service time, titanium will be preserved completely and can be platinum-plated again, if desired. When treated according to specification the platinum-plated titanium anode can reach a service life of 10 years and more.