Zinc (galvanized) – metal coating with a layer of zinc to protect against corrosion. Suitable for flat or slightly curved surfaces that are not subject to mechanical stress.

The protection method is based on the following principle: most metals (for example, zinc, tin, aluminum) are oxidized in air, and a dense protective film of oxidized metal compounds forms on the metal surface. This film prevents oxygen from penetrating deep into the metal and thus stops further oxidation of the metal. However, in the case of iron, the process is different. The resulting compounds of oxidized iron (for example, hydroxides) have a larger volume than the original metal, as a result of the resulting film of hydroxides immediately breaks down and turns out to be loose. Such a loose, loose and fragile film freely passes oxygen deep into the unoxidized metal, and the process of its oxidation continues. Iron is unable to protect itself from further oxidation and rust forms. If the iron is coated with a layer of metal that forms a protective film, such as tin or zinc, then their protective film will not allow oxygen to penetrate both to the metal of the coating and to the iron under the coating. Consequently, the iron will be protected from corrosion. Both galvanizing (zinc) and tinning (tin) work in about the same way, the differences will be if the coating is damaged at the place of corrosion and the iron is exposed. Zinc and iron form a galvanic pair, in which iron is a less active metal, as a result, zinc in the coating composition enters into the corrosion reaction first, and the base metal (iron) remains practically “untouched”. Tin and iron also form a galvanic pair, however, iron in it will be a more active metal, as a result, tin will many times accelerate the process of corrosion of iron in the place of damage to the coating.

The thickness of the zinc layer depends on the temperature and duration of the galvanizing process and ranges from 6 microns for galvanizing to 1.5 mm.