Which two points of galvanized steel strip play the role of corrosion protection

The significance of hot-dip galvanizing of galvanized steel strip is that after the steel strip is covered with a layer of zinc coating, the corrosion resistance is greatly improved, the materials and resources can be saved, and good economic and environmental benefits can be brought into play. The protective effect of zinc coating on steel strip is as follows:

Galvanized steel strip

(1) When the surface of galvanized sheet is in good condition, only zinc corrosion occurs. The corrosion rate of zinc is very slow and the service life of zinc corrosion products is 15 ~ 30 times of that of non galvanized steel.

(2) The most common situation is that the surface of galvanized sheet is scratched during processing, installation and use, or the coating is partially damaged due to other reasons. The steel strip is exposed to the environment from the wound. If the coating is non-metallic, the exposed steel base will be corroded quickly. However, the special sacrificial protection property of galvanized sheet slows down the corrosion rate.

In this case, zinc in the coating and iron in the steel strip form a primary battery in a humid environment. Since the standard electrode potential of zinc is only - 1.05v, lower than that of iron, zinc is oxidized as anode and iron as cathode