Galvanizing reaction
Hot-dip galvanizing — Principle

Galvanized coating is not simply a deposit of zinc on the steel surface, as paint might be. It's really a metallurgical reaction of double diffusion between zinc and iron.

This diffusion leads to the formation of layers of Fe-Zn intermetallic alloys.

The galvanized coating therefore consists of :

• one or more layers of intermetallic compounds depending on the nature of the bath (presence of aluminium in particular) and the technological process;

• a final layer of external zinc, which is drawn into the part by capillary action.