The High Performance of Mixed Metal Oxide Coated Titanium Anodes for ICCP System

Apr 07, 2021

The High Performance of Mixed Metal Oxide Coated Titanium Anodes for ICCP System

Impressed current cathodic protection(ICCP) systems provide cathodic current from an external power source. A DC power force current to discharge from expendable anodes to the electrolyte, and onto the structure to be protected. Although the current is generated by a corrosion reaction at the auxiliary anode, the energized materials used for the auxiliary anodes either do not corrode or corrode very slowly because corrosion-resistant materials and alloys are used. The primary corrosion reaction is the oxidation of negatively charge ions available around the anode and the more that this is the primary reaction, the longer the anode will last.

Mixed Metal Oxide coated titanium anodes consist of electrocatalytic noble precious metal coated on titanium substrates fabricated by thermal decomposition method. The electrocatalytic coatings are formulated primarily of platinum group metals such as ruthenium, iridium, platinum,
tantalum, etc. The coatings are applied by spraying or dip coating aqueous salts of the metals onto an acid etch cleaned titanium substrate and heating to several hundred degrees Celsius. Multiple layers of coatings may be applied by this process to provide the desired final coating thickness.

This mixed metal oxide coating is highly conductive crystalline, corrosion, and acid resistant, this MMO coated titanium anodes can work in a harsh working environment.  

The very thin precious metal oxide anode coating is exceptionally durable in combination with the ductile commercially pure titanium substrate. It has been tested at current densities of over 2000 amperes per square foot of anodic current discharge. It is fabricated primarily of precious metal and refractory metal oxides in sufficient quantities and ratios to provide a defined life expectancy. Because the coating is already oxidized, it is not consumed when operating as an anode in cathodic protection applications and is dimensionally stable. This dimensional stability is a major advantage in that the resistance to earth does not increase with time as it does with other more consumable anodes such as HSCI or Graphite. Since this coating supports the evolution of both oxygen and chlorine, it can be a good choice for freshwater, seawater, mud, brackish water, and coke environments.