Both methods add a protective layer of zinc to the steel. Zinc protects the steel by sacrificing itself – called a “sacrificial anode”. When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that stops further corrosion in many circumstances, protecting the steel below from the elements. Zinc is also able to protect at a distance. All of the surface need not be covered with zinc. Ships attach large blocks of zinc to the hulls to protect the hull from corrosion. Ships need not cover the hull with zinc anodes. They are placed near and in electrical contact with the hull.
Read More