Highly galvanized layer means that the plating layer is very thick. This is for hot-dip galvanized sheets, because electro-galvanization cannot be too thick. The thickness of the hot-dip galvanized sheet coating is generally above 20 microns, even up to 100 microns. The weight of galvanized layer per square meter is usually expressed as 145 grams per square meter, and the coating layer is about 20 microns. However, it is not easy to control the thickness of the hot-dip galvanized sheet in a relatively thin range.
The melting point of zinc is 419.5°C, and it is chemically active. In the air at room temperature, a thin and dense basic zinc carbonate film is formed on the surface to prevent further oxidation. When the temperature reaches 225°C, zinc is violently oxidized, showing white zinc oxide. After high-temperature grilling, Galvanized Steel Sheet surface anti-corrosion layer material is oxidized, so the galvanized sheet cannot withstand high temperature, the heated surface will change color, or other protective materials on the surface will easily turn yellow after oxidation.
The surface of Galvanized Steel Sheet should be free of oily or waxy components and other stains or dust, which can improve the adhesion of putty;
Theoretically, it is not recommended to make veneer paint or primer on the basis of the surface of similar galvanized sheet that is too smooth. If necessary, corrosion treatment (such as hydrochloric acid) can improve the bonding strength with putty and paint;
Putty should be adjusted according to the standard ratio and the ratio of curing agent. Excessive proportion will reduce the adhesion and physical properties of putty (for example, it is too brittle and loses toughness);
Putty should be used within the warranty period and be applied as thinly as possible to prevent the surface and the base material galvanized sheet from excessive temperature difference and inconsistent stress, shrinking and expansion, and peeling off the layer leading to complete separation.