The protection of the zinc layer on the iron matrix has two principles: on the one hand, although zinc is more active and easy to oxidize than iron, its oxide film is not as loose and dense as iron oxide. The dense oxide layer formed on the surface inhibits the further oxidation of zinc inside. Especially after passivation galvanized layer, the surface oxidation layer is more thick and dense, and it has a high oxidation resistance.
On the other hand, when the surface of the galvanized layer is damaged, exposing the internal iron matrix, because zinc is more active than iron, then zinc assumes the role of sacrificing zinc anode, zinc will be oxidized before iron, thus protecting the iron layer from damage.
Zinc adhesion on galvanized wire surface and thickness of zinc layer
A. When the thickness of the plating is 3-4 mm, the zinc attachment amount should be less than 460 grams/meter, that is, the average thickness of the zinc layer is not less than 65 microns.
B. When the thickness of the plating is greater than 4 mm, the zinc attachment amount should not be less than 610 grams/meter, that is, the average thickness of the zinc layer is not less than 86 microns.
C, coating uniformity: galvanized layer is basically uniform with copper sulfate solution test etched five times without exposing iron.
D, coating adhesion; The zinc layer of the plating should be firmly combined with the base metal and have sufficient adhesion strength, and will not fall off or bulge after hammering test.
Post time: 06-12-23