The greater the potential difference between two metals, the greater the driving force for the corrosion process. Zinc is high enough in the galvanic series to act as an anode in couples with most of the common metals. The difference in potential between two areas causes current to flow from the cathode to the anode through the metal, and from the anode to the cathode through the electrolyte to complete the circuit. When the current enters the electrolyte, metal ions go into solution, causing corrosion of the anode. This corrosion can be prevented if it is connected electrically by a wire or rod to zinc, also in contact with the electrolyte.
Cathodic protection is effective in such diverse mediums as salt water, fresh water, and most soils.
The structures most frequently protected are underground pipelines and ship hulls. All rights reserved. Legal notices and trademark attributions.