Sacrificial anode

From GAWDAwiki

Sacrificial anodes are metals used in cathodic protection that are more electrically active than the steel tanks they are meant to protect. This higher electrical activity encourages corrosive currents to exit from the anodes instead of the tanks. The name “sacrificial anode” is derived from the fact that the tanks are protected from corrosion at the expense of the anodes. When the anodes have been depleted, they must be replaced in order to continue protection of the tanks.^[1]

Impressed current systems are alternative methods of cathodic protection.

References

1. http://www.epa.gov/oust/ustsystm/cathodic.htm