Impressed Cathodic Protection
When two metals are placed in an environment that is electrolytically conducting, such as soil or salt water, a galvanic couple can be created between the two metals. In this situation, the more active metal corrodes at a faster rate than the other metal, a process called galvanic corrosion. Cathodic protection involves the use of a sacrificial anode - an active metal is placed on the surface to act as the anode in an electrochemical reaction. As a result, the anode takes on the galvanic corrosion. On large surfaces, it is necessary to link the anode to a DC power supply in order to drive more current through the anode. This process is referred to as Impressed Current Cathodic Protection.
