Cathodic Protection is a method of protecting metal from corrosion.
Corrosion is an electro-chemical reaction, in which metal reacts with moisture. The metal acts as an anode, or source of electrons for the reaction. The best-known type of corrosion is rust.
Coatings
Metal can be protected from corrosion with coatings that prevent contact with moisture. Coatings may require frequent renewal.
Passive Cathodic Protection
Metal can be protected from corrosion by attaching a second metal which is a better anode than the metal being protected. The original metal then acts as a cathode.
For example, copper can be protected from corrosion by attaching iron. This technique was first used to protect the copper-clad hulls of British warships in 1824.
The second metal itself corrodes and eventually needs to be replaced; for this reason, it is sometimes called a sacrificial metal.
Impressed Current Cathodic Protection (ICCP)
ICCP involves an electrical circuit which provides a source of free electrons through an anode. Because the electron flow is provided from a DC power source, the anode does not corrode and doesn't need to be replaced.
Applications
Cathodic protection is used to prevent corrosion on storage tanks, pipelines, ships and boats, bridge piers, and other structural elements that come in contact with moisture. Specialized corrosion engineering firms design and implement systems to protect metal in large-scale commercial and construction projects.
