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HaiGang Yunyi
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Tianjin Haigang Steel Coil
Service first, quality assured. More dedicated and focused on crafting even better boards.
26
2020
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10
Comparison Between Electroplated Zinc and Hot-Dip Galvanized Zinc
Electro-galvanizing, also known as cold-spray zinc plating, is a process that uses photoelectrocatalysis to oxidize zinc ingots as the anode. After losing electrons, zinc atoms become positive ions and dissolve into the electrolyte solution. Meanwhile, steel serves as the cathode; zinc ions gain electrons at the steel surface, transforming back into zinc atoms that deposit onto the steel surface, thereby forming a coating.
There is a significant difference between hot-dip galvanized sheets and electrogalvanized sheets in terms of the amount of zinc coating applied. The zinc coating weight for hot-dip galvanizing can never be very low—typically, it is at least 50 to 60 g/m² on both sides, and can even reach up to 600 g/m² in some cases. In contrast, the zinc coating layer in electrogalvanized sheets can be extremely thin, with a minimum thickness of as little as 15 g/m². However, if a thicker coating is required, the production line speed slows down considerably, making this process unsuitable for the processing characteristics of automated production lines. Generally, the maximum coating weight for electrogalvanized sheets is around 100 g/m².
Hot-dip galvanized sheets and electrogalvanized sheets differ in their coating microstructures. In hot-dip galvanized sheets, there is a slightly brittle chemical layer between the pure zinc coating and the steel substrate. During crystallization of the pure zinc coating, zinc flowers typically form, resulting in a uniform coating free of pores. In contrast, the zinc molecules in an electrogalvanized coating merely deposit and dissolve on the surface of the steel substrate through physical adhesion, leaving numerous pores. As a result, such coatings are highly susceptible to crevice corrosion caused by corrosive substances. Therefore, hot-dip galvanized sheets are more resistant to corrosion than electrogalvanized sheets.
The heat treatment methods for hot-dip galvanized and electro-galvanized sheets are also completely different. Hot-dip galvanized sheets typically use cold-rolled steel as the raw material and undergo continuous quenching and galvanizing in a hot-dip galvanizing bath. After being heated briefly, the steel strip is rapidly cooled down again; as a result, its tensile strength and ductility may be somewhat compromised. Consequently, their stamping performance is inferior to that of cold-rolled steel sheets that have undergone specialized production-line degreasing and quenching. Electro-galvanized sheets, on the other hand, use cold-rolled steel as the raw material and generally maintain the same processing characteristics as cold-rolled steel. However, their more complex manufacturing process does increase product costs. In summary, hot-dip galvanized sheets have lower production costs and a wider range of applications, making them the dominant type in the galvanized sheet market.
Electroplating zinc involves zinc plating based on electrode reactions, whereas hot-dip galvanizing involves immersing the raw material into a bath of molten zinc for hot-dip galvanizing; this process involves both chemical reactions between metals and physical phenomena.
During hot-dip galvanizing, the surface of the raw material consists of a layer of chemical compounds between metal layers, followed by zinc; in contrast, the surface of electrogalvanized products is simply zinc, with no underlying layers.
Electro-galvanized zinc coatings are relatively thin, while hot-dip galvanized zinc coatings tend to be thicker.
Electro-galvanizing cannot be mass-produced and has a lower production volume, whereas hot-dip galvanizing can be mass-produced with high output.
The cost of electro-galvanizing has increased, so the price is higher.
The basic principle of corrosion protection for both electro-galvanizing and hot-dip galvanizing is the same. The only difference lies in their respective processing techniques.
After electro-galvanizing, the surface is smooth and has a bright appearance. However, since the zinc layer is only an overlay, it will eventually peel off over time.
Hot-dip galvanizing isn't as aesthetically pleasing as electroplating in some aspects. However, the zinc layer has better penetration, and its service life is longer compared to electroplated coatings. The process is relatively lengthy.
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We primarily produce various products including galvanized strip steel, pickled strip steel, and cold-rolled strip steel. These products are widely used in industries such as construction, mechanical manufacturing, automotive, and household appliances.
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Shuangtang High-end Hardware Products Industrial Park, Jinghai District, Tianjin City
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