Cathodic protection works by supplying electrons to the metal that needs protection. This can be achieved through two main methods: sacrificial anode and impressed current.
Sacrificial Anode In this method, a more reactive metal (anode) is placed in contact with the protected metal (cathode). The anode corrodes instead of the protected metal. Typical sacrificial anodes include zinc, magnesium, and aluminum.
Impressed Current This method uses an external power source to provide a constant flow of electrons. The protected metal becomes the cathode, while an inert anode, such as graphite or platinum, is used.
