Zinc aluminum magnesium corrosion resistance and self-healing principle of scratch cuts
First, a theoretical analysis is performed. ZAM board has unique corrosion resistance properties, especially cut protection properties. The analysis is divided into two situations: the plane situation without scratches and the situation with cuts and scratches.
1. When the ZAM surface is not scratched
The combined action of magnesium and aluminum contained in the coating will produce a dense oxide protective film with high adhesion on the surface of the coating during long-term use, isolating the coating from the external corrosive environment and playing an isolation and anti-corrosion role. , to prevent corrosion of the coating. Magnesium is a more active metal than aluminum and is extremely easily oxidized in the air. The oxide film formed by solid magnesium is also dense, which can effectively protect the internal tissue and prevent further oxidation. Because magnesium is different from aluminum, it is evenly and finely distributed in the coating, so that the oxide film covers the entire coating surface, so that all the structures in the coating are protected.
2. When the coating is scratched or has cuts
The magnesium dissolved from the coating can form a fine, dense oxide film containing magnesium on the cut section, covering the exposed steel base in the scratched or cut section, thereby improving its corrosion resistance. In this case, the sacrificial anti-corrosion effects of zinc and the isolation anti-corrosion effects of aluminum and magnesium can also be brought into play. On this basis, because magnesium is very active, it can reduce the loose oxides on the surface of the steel plate and replace them with dense magnesium oxides, thereby protecting the exposed steel base.
ZAM incision site protection principle
The incision exposure test showed that the fracture showed a certain red color in the early stage of the test, but the red color would not develop seriously. After 3 years, the original red color turned into gray-black. After testing, it was found that the oxide film at the fracture site contained complex components such as zinc, magnesium, aluminum, oxygen, iron, chlorine, and sulfur.
