According to the different galvanizing methods, production processes and galvanizing amounts, it is divided into hot-dip galvanized steel sheets (GI) and electrolytic galvanized steel sheets (EG). There are big differences in their characteristics in various aspects:
From the appearance point of view, the surface brightness of EG is better than that of GI, but through surface treatment, GI can also achieve very good brightness;
A layer of zinc-iron alloy can be formed between the galvanized layer of GI and the steel plate, which can make the galvanized layer stronger. However, the zinc-plated layer of EG is thin and cannot form a zinc-iron alloy layer. Therefore, GI has better anti-corrosion and anti-rust properties. For EG; the galvanizing amount of GI can reach more than 45 grams per square meter, while the galvanizing amount of EG is only about 20 grams. The amount of galvanizing will directly affect the radiation protection and oxidation resistance of the steel plate;
Compared with EG, GI has stronger adsorption to electromagnetic waves, especially low-frequency electromagnetic waves. At the same time, this material also has better heat dissipation and conductivity, and can effectively resist high-frequency electromagnetic waves.
The electroplated ones are as bright as mercury, while the hot-plated ones are black. Zinc is easily soluble in acid and alkali, so it is called an amphoteric metal. Zinc hardly changes in dry air. In humid air, a dense basic zinc carbonate film will be formed on the surface of zinc. In sulfur dioxide, hydrogen sulfide and marine atmospheres, zinc has poor corrosion resistance. Especially in high-humidity and high-temperature atmospheres containing organic acids, the galvanized layer is easily corroded.
The standard electrode of zinc is -0.76V. For steel, the new coating is an anodic coating. It is mainly used to prevent corrosion of steel, and its protective performance is closely related to the coating.
The difference between electro-galvanizing and hot-dip galvanizing:
1. The thickness is different, the electro-galvanized zinc layer is thinner, and the hot-dip galvanized zinc layer is thicker (much thicker);
2. The appearance is different, the appearance of electro-galvanized is smooth and bright, while the appearance of hot-dip galvanized is rough and has poor luster;
3. The application environments are different, electro-galvanizing is used in general situations, and hot-dip galvanizing is used in outdoor situations.
