The anticorrosive zinc of galvanized steel pipe has a negative electrode potential than iron. When zinc and iron form a microbattery, zinc is the anode and iron is the cathode. When it is corroded, zinc dissolves and iron is not harmed. When the galvanized layer has small cracks or damage, the zinc will be in the form of a dedicated anode to prevent the steel at the crack or damage from rusting. This is the main feature of the galvanized layer being better than other coatings.
When hot-dip galvanized steel pipe is dipped galvanized, the zinc-iron alloy layer and the steel matrix and zinc layer are all metallurgically bonded, which is stronger than the combination of paint and steel.
The anticorrosive zinc layer of galvanized steel pipe has a shielding and protective effect on steel. Zinc forms a shielding layer on the surface of the steel substrate in the atmosphere or other environments. The corrosion process of zinc increases its ability to form a shielding layer. This is because zinc reacts with oxygen, carbon dioxide, and moisture in the air to form an anti-corrosion by-product basic zinc carbonate film.
The zinc-iron alloy layer between the substrate and the pure zinc layer contains 90% zinc, which has an electrochemical protective effect similar to zinc; the thicker the coating, the longer the service life, and the service life is basically proportional to the thickness.