In nature, most metals exist in a chemical state. It is only through refining and the application of energy that they are transformed from the ionic to the atomic state. However, it is in the nature of metals to return to their natural state. The process by which a metal reacts with the surrounding electrolyte and changes from an atom to an ion is called corrosion. Metal corrosion is so widespread in our lives that we are unaware of its occurrence and development. Foreign statistics show that each year due to corrosion and scrap metal materials, equivalent to about 20% to 40% of the annual production of metal, the world's annual loss of metal due to corrosion of more than 100 million tonnes. Metal corrosion directly and indirectly cause huge economic losses, according to relevant national statistics, annual economic losses due to corrosion: the United States of America about 500 billion US dollars, an average of 2,000 US dollars per person; the United Kingdom for the total value of national economic output of 3.5%; Japan for the total value of national economic output of 1.8%.

Most long-distance pipelines are buried, because the soil contains moisture, air, acid, alkali and water-soluble mineral salts, as well as microorganisms, these factors will cause the metal pipeline to corrode. Therefore, anti-corrosion measures must be taken to ensure the service life of the pipeline and to reduce the economic losses due to corrosion. With currently known anti-corrosion techniques, 30% of corrosion losses can be recovered, so active corrosion protection is of great economic importance.