Why Platinum Plated Titanium Electrodes is Applied in the Electroplating Industry?

Why Platinum Plated Titanium Electrodes is Applied in the Electroplating Industry?

The corrosion resistance of titanium is based on a stable self-curing oxide film on the metal surface which immediately develops in the air at normal or elevated temperatures. Titanium remains corrosion resistant as long as this oxide skin is maintained or constantly reproduced. However, this oxide skin, developing also on the metallic bright material, has a very high electric resistivity so that a charge exchange with the electrolyte cannot take place when using titanium for electrodes. But when titanium is costed with platinum, this platinum coating resumes the function of the anode and enables the current to flow easily from the anode to the electrolyte. Hereby the platinum-plated titanium anode combines a large number of advantages. It is much cheaper, lighter, and stronger than e. g. solid platinum anodes and operates without any sign of dissolution even in the case of porous platinum coatings.

Electroplating uses with great success platinum-plated titanium anodes in acidic precious metal baths {rhodium, palladium, gold, etc.) as undissolvable anodes. For rhodium-plating baths containing sulphuric acid, the concentration of sulphuric acid is of striking importance for the economical utilization of platinum plated titanium anode. If the concentration of sulphuric acid rises too abruptly, say by more than 10 %, titanium can be attacked through the pores of the platinum coating. This means that in case of prolonged service interruptions the platinum-plated titanium anodes should either be polarized slightly anodically or removed from the bath.