Analysis of high temperature resistance of galvanized sheet
I
High galvanized layer refers to the coating is very thick, this is said to hot galvanized sheet, because the electric galvanized can not be plated too thick. Hot galvanized sheet coating thickness is generally more than 20 microns, or even up to 100 microns. Commonly used per square meter galvanized layer weight, 145 grams/square meter, coating is about 20 microns. However, it is not easy to control the thickness of hot dip galvanizing in a relatively thin range.
The melting point of zinc is 419.5℃, and its chemical properties are active. In the air at room temperature, a thin and dense basic zinc carbonate film is formed on the surface, which can prevent further oxidation. When the temperature reached 225℃, the zinc was oxidized violently, showing white zinc oxide. After high temperature barbecue galvanized sheet surface anticorrosive layer material is oxidized, so galvanized sheet can not withstand high temperature, heating the surface will change color, or the surface of protective other substances after oxidation easy to turn yellow.
