Activated Titanium Anode Systems and Organic Coatings in Cathodic Protection

Activated Titanium Anode Systems and Organic Coatings in Cathodic Protection

The cathodic protection system shall include an anode system intended to distribute the cathodic protection current to the surfaces of the embedded steel to be protected. Impressed current cathodic protection systems shall further incorporate positive and negative direct current cables between the anode and the steel, respectively, and the DC power supply, which is the source of the cathodic protection current.

Organic Coatings in Cathodic Protection
These coatings are used as impressed current anodes. The anode system shall comprise an organic conductive coating (solvent-based or water soluble, containing a carbon conductor) and a series of conductors (primary anodes) fixed to the concrete surface or integrated into the coating, in order that the conductors can distribute current within the coating. The conductors shall be of material able to resist anodic reactions, e.g. platinum-coated or platinum-clad titanium or niobium which may be copper-cored, or mixed metal-oxide-coated titanium.


Thermally Sprayed Metallic Coatings in Cathodic Protection
The anode system shall comprise a thermally sprayed metallic coating of Zn, Al-Zn, Al-Zn-In, or Ti. The Zn coatings are used both as impressed current anodes and as galvanic anodes; the Al-Zn and Al-ZnIn alloy anodes are used as galvanic anodes. Ti is used as an impressed current anode with a catalytic spray to lower the anode-to-concrete interfacial resistance.

When thermal sprayed metallic coatings are used as galvanic anodes, they may be applied directly to the reinforcement/steel where it is exposed, as well as predominantly to the sound concrete surface. A humectant may be applied to thermal sprayed metallic coatings used as galvanic anodes to enhance their performance. To avoid atmospheric corrosion and prolong the lifetime of the anode, an organic top coating may be applied to the thermal sprayed metallic layer. The combination of metallic coating and connectors shall be demonstrated by trials or past projects to enable the design anode performance to be achieved. The particular application technique selected shall be demonstrated by trials or past projects to enable the design anode performance to be achieved. The adhesion of the coating to the concrete, subject to appropriate surface preparation and the above application technique, shall be suitable to achieve the full design life of the anode system.

Activated Titanium Anode Systems in Cathodic Protection
These anodes are used as impressed current anodes. The anode system shall comprise a substrate of titanium and an electrocatalytic coating containing oxides of platinum group metals, platinum, iridium, or ruthenium along with oxides of titanium, zirconium, and tantalum, together with anode/cable connections and a cementitious overlay or surround. These anodes are frequently described as MMO/Ti anodes (mixed metal-oxide-coated titanium) or dimensionally stable anodes (DSA). The coating composition and thickness, or mass per unit area, shall be demonstrated by trials and/or laboratory testing to enable the design anode performance to be achieved.