Galvanized or zinc plating. Zinc is easily soluble in acid and alkali, so it is called amphoteric metal. Zinc hardly be changed in dry air. In humid air, a basic zinc carbonate film is formed on the zinc surface.
In the atmosphere containing sulfur dioxide, hydrogen sulfide and ocean, the corrosion resistance of zinc is poor. Especially in the high-temperature and high-humidity atmosphere containing organic acid, the zinc coating is easily corroded. The standard electrode potential of zinc is -0.76V. For the steel substrate, the zinc coating is an anodic coating. It is mainly used to prevent corrosion of steel. Its protective performance has a great relationship with the thickness of the coating.