鋼鐵由於產量豐富，加工容易，物性良好，在工業上是爲應用最廣的金屬之一，但卻極易與周圍之水分起化學作用導致所謂的生銹。對於防止生銹的方法而言，除了最常見的油漆，電鍍之外雖然還有很多方法，但是對於長期設置在水中或土壤中之鋼鐵，譬如海岸邊之鋼板椿，地底下之油管等，當實施定期性之保養工作時，顯得非常之不方便。假如利用電化學之金屬防蝕方法非但效果非凡而且能減低維護之成本。
電化學之金屬防蝕一般稱之爲應陰極防蝕，陰極防蝕可分爲犧牲陽極法及外加電流法二種其基本動作原理是強迫使欲保護之金屬成爲陰極而達到不被腐蝕之目的。
Steel is one of the most widely used metals in industries due to its abundant production, easy processing, and fine physical characteristies. It, however, is prone to get rusted out of chemical reactions with moisture in the surrounding environment. In addition to painting and plating, many methods are available for preventing corrosion of steel, but most of them fail to conveniently protect such steels embedded in water or soil for long, as offshore steel sheet piles and underground pipelines which require regular maintenance. Electrochemical approach to proteoting metals against corrosion, on the other hand, has been proved a measure not only effective but also economic in maintenance cost.
Electrochemical protection against metal corrosion is often called cathodic protection. It may be applied by adopting either galvanic anode method or impressed current method. Its principle is to make the metal to be protected become the cathode and thus achieve the objectives of protecting the metal.
