Hot-dip galvanization is a form of
galvanization. It is the process of coating
iron and
steel with a layer of
zinc by immersing the
metal in a bath of molten zinc at a temperature of around . 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 protects the steel underneath from further
corrosion in many circumstances.
Galvanized steel is widely used in applications where
corrosion resistance is needed without the cost of
stainless steel, and can be identified by the
crystallization patterning on the surface (often called a "spangle").