Briefly speaking, the powerful anti-corrosion function of aluminized zinc color steel plate
Summary: Galvanized sheet, as a continuous production process of aluminum zinc sheet, can be divided into two methods: galvanizat...
Galvanized sheet, as a continuous production process of aluminum zinc sheet, can be divided into two methods: galvanization and hot-dip galvanization. Electrogalvanizing is the process of electroplating a layer of zinc metal or zinc alloy on a gold plate. Hot dip galvanizing, also known as hot dip galvanizing, is to immerse the protected metal products into the molten zinc metal to form a protective metal coating on its surface. Compared with electroplating, the hot-dip galvanized layer is thicker; Under the same environment, its life is longer. The corrosion process of zinc in atmosphere is similar to that of steel in atmosphere. Chemical oxidation corrosion and electrochemical corrosion occur on the zinc surface, accompanied by water film condensation.
In the neutral or weak acidic atmospheric environment, the corrosion products of the galvanized layer of steel plate formed after corrosion are insoluble compounds (zinc hydroxide, zinc oxide and zinc carbonate), which will precipitate in the form of precipitation to form a dense thin layer, generally up to 8 um "thick. The film has a certain thickness, is not easy to dissolve in water, and has strong adhesion. Therefore, it can act as a barrier between the atmosphere and the galvanized sheet to prevent further development of corrosion. The protective zinc coating is damaged. Part of the steel surface is exposed to the atmospheric environment. At this time, zinc and iron form a micro battery. The potential of zinc is obviously lower than that of iron. As an anode, zinc acts as a sacrificial anode to protect the steel plate substrate and prevent corrosion of the steel plate.
Color coated aluminum zinc plate is a kind of liquid coating, which is applied on the clean metal surface by brushing or rolling, and can get a paint film of the same thickness after heating and curing. In addition to separating metal from corrosion medium, paint film can also passivate metal with the help of some pigments in the paint (such as lead, zinc chromate, etc.) to achieve permanent anti-corrosion effect.
From the perspective of anti-corrosion mechanism of color coated steel plate, organic coating (including solid coating and undercoat) is an isolating material, which separates the substrate from the corrosive medium to achieve anti-corrosion effect.