In many electrolytic cells, titanium finds use as an anode or a cathode. The electrode may be made of an alloy of titanium and a rare earth metal, which may have a surface coating of a different material.
An exemplification of this invention provides an electrode with an electroconductive titanium-rare earth metal alloy substrate, and a bimetal spinel layer coated with platinum from 10 to 100 micro-inches thick. The bimetal spinel layer provides an added site for surface catalyzed reactions.
The electrode may also be used as a bipolar electrode of the titanium-rare earth metal alloy. One surface of the electrode faces a prior anode and functions as the cathode of a subsequent electrode. The opposite surface of the electrode is coated with an electrocatalytic material and faces the cathode of a subsequent electrocatalytic electrode, thereby functioning as the anode of the bipolar electrode.
Titanium is very resistant to anodic corrosion in seawater and this has led to its use for marine and power station ductwork, jet impingement nozzles, and in dental implants. It also finds extensive use as a starter anode for copper refining and other electrical applications.
Superimposed AC ripple and brine dilution are two unexpected hazards that have been known to affect the longevity of titanium electrodes. Moreover, local acidity has been recognised as an additional cause of failure.
The use of noble metal salts as a paint to coat electrodes is now widely practised and this has provided considerable improvement in coating adhesion, visual platinum coverage, and resistance to the electrode being undermined in acidic environments. However, it is important to stress that the use of soluble noble metal salts in a solvent must be carefully managed and that the paint must be decanted before it is considered suitable for application.