NEWS

Electrogalvanizing, commonly known as cold galvanizing, is the use of electrochemical method, the zinc ingot as the anode, zinc atoms lose electrons and become ionic state dissolved in the electrolyte, and the steel strip as the cathode, zinc ions in the steel strip to obtain electrons reduced into zinc atoms deposited on the surface of the steel strip, forming a coating.

There is a great difference in the amount of galvanizing between hot galvanized sheet and electrogalvanized sheet. The galvanizing amount of hot dip galvanizing can not be too small, generally the minimum is 50-60g /m2 on both sides, and the maximum is 600g/m2. The galvanized layer of electrogalvanized sheet can be very thin, the minimum is 15g/m2, but if the coating is thicker, the production line is very slow, does not adapt to the process characteristics of modern units, and the maximum is generally about 100g/m2. Because of this, the production of electrogalvanized sheet is greatly limited.

There are fundamental differences between hot galvanized sheet and electrogalvanized sheet in the microstructure of the coating. There is a slightly brittle compound layer between the pure zinc coating of hot galvanized sheet and the steel strip substrate, and the pure zinc coating mostly forms zinc flowers when crystallizing, and the coating is uniform without pores. The zinc atoms of the electrogalvanized layer are only deposited on the surface of the steel strip, and are attached to the surface of the steel strip by physical action, there are many holes, and it is easy to cause pitting due to corrosive media, so the hot galvanized sheet is more corrosion resistant than the electrogalvanized sheet.

Hot galvanized and electrogalvanized sheet heat treatment process is also completely different, hot galvanized sheet is generally cold hard plate as raw material, continuous annealing and hot galvanized in the galvanized line, steel strip in a short time after heating and cooling, so the strength and plasticity are affected to a certain extent, its stamping performance than the same cold hard plate after professional production line degreasing annealing cold rolled plate poor. Electrogalvanized sheet takes cold-rolled sheet as raw material, which basically guarantees the same processing performance of cold-rolled sheet, but its complex process flow also increases the production cost. In short, the production cost of hot galvanized sheet is lower, the application range is wider, and it has become the main variety of galvanized sheet market.

Electrogalvanizing is galvanized by electrode reaction, and hot-dip galvanizing is the raw material immersed in the zinc pot for galvanizing, which is the intermetallic reaction and physical reaction.

In hot dip galvanizing, the surface of the raw material is a layer of intermetallic compounds, and then zinc, and the surface of electric galvanizing is zinc, there is no intermediate layer.

The zinc layer of electric galvanizing is thinner, and the zinc layer of hot dip galvanizing is thicker

Electrogalvanizing can not be mass produced, the output is low, and hot-dip galvanizing can be mass produced, the output is high.

The surface condition and corrosion resistance of electroplating are better than that of hot dipping zinc

The binding force of electric galvanizing is better than that of hot dip galvanizing, so the price is expensive

The cost of electrogalvanizing is high, so the price is high. When the price of hot dip galvanized zinc aluminum alloy is high, more than 4W/ton.........

The anti-corrosion principle of electric galvanizing and hot dip galvanizing is the same. It's just that the process is different.

After electrogalvanizing - smooth surface. Appearance bright. However, because the zinc layer is attached to it, it will fall off over time.

Hot dip galvanizing - some not as beautiful as electroplating. However, the zinc layer is permeable and the use time is longer than that of electroplating.

1, hot galvanized sheet generally thicker zinc layer, about 10um or more, strong anti-corrosion ability. So it is a commonly used galvanizing process. The electrogalvanizing is very thin, about 3-5um, the hot plating surface is rough, bright, and there are zinc flowers in severe cases, and the electroplating is smooth and gray (dirty).

The galvanized steel plate made by electroplating has good processing properties. However, the coating is thin and the corrosion resistance is not as good as that of hot-dip galvanized sheet. Cold galvanized sheet is electric galvanized, galvanized amount is very small, only the outer tube wall galvanized (hot plating - both inside and outside plating), only 10-50g/m2, its own corrosion resistance than the hot galvanized sheet tube is very different.

2, the chemical industry general galvanizing more, suitable for small parts; Hot galvanized sheet is generally used in power equipment and components, suitable for large components and equipment.

Electrogalvanizing, commonly known as cold galvanized sheet, is the use of electrochemical method, the zinc ingot as the anode, zinc atoms lose electrons and become ionic state dissolved in the electrolyte, and the steel strip as the cathode, zinc ions in the steel strip to obtain electrons reduced into zinc atoms deposited on the surface of the steel strip, forming a coating.

In order to remove the iron oxide on the surface of the steel pipe, after pickling, the steel pipe is cleaned by ammonium chloride or zinc chloride aqueous solution or ammonium chloride and zinc chloride mixed aqueous solution tank, and then sent to the hot dip plating tank.

3, hot galvanized sheet and electrogalvanized sheet in the amount of galvanizing has a great difference. The galvanizing amount of hot galvanized sheet can not be too small, generally the minimum is 50-60g /m2 on both sides, and the maximum is 600g/m2. The galvanized layer of electrogalvanized sheet can be very thin, the minimum is 15g/m2, but if the coating is thicker, the production line is very slow, does not adapt to the process characteristics of modern units, and the maximum is generally about lO0g/m2. Because of this, the production of electrogalvanized sheet is greatly limited.

4, hot galvanized sheet and electrogalvanized sheet have fundamental differences in the coating structure. There is a slightly brittle compound layer between the pure zinc coating and the steel strip substrate, and the pure zinc coating mostly forms zinc flowers when crystallized, and the coating is uniform without pores. The zinc atoms of the electrogalvanized layer are only deposited on the surface of the steel strip, and are attached to the surface of the steel strip by physical action, there are many holes, and it is easy to cause pitting due to corrosive media, so the hot galvanized sheet is more corrosion resistant than the electrogalvanized sheet.

5, hot galvanized sheet and electrogalvanized sheet heat treatment process is also completely different, hot galvanized sheet is generally cold hard plate as raw material, continuous annealing and hot galvanized sheet in the galvanizing line, steel strip in the short time after heating and cooling, so the strength and plasticity are affected to a certain extent, its stamping performance than the same cold hard plate after professional production line degreasing annealing cold rolled plate poor. Electrogalvanized sheet takes cold-rolled sheet as raw material, which basically guarantees the same processing performance of cold-rolled sheet, but its complex process flow also increases the production cost. In short, the production cost of hot galvanized sheet is lower, the application range is wider, and it has become the main variety of galvanized sheet market.

6, hot galvanized sheet tube is the reaction of molten metal and iron matrix to produce an alloy layer, so that the matrix and the coating are combined. Hot galvanized sheet has the advantages of uniform coating, strong adhesion and long service life. Regular galvanized pipe manufacturers, in order to ensure quality, most do not use electric galvanizing (cold plating). Only those small enterprises with obsolete equipment use electric galvanizing, of course, their prices are relatively cheap. The Ministry of Construction has formally announced the elimination of cold galvanized sheet tubes with backward technology, and it is not allowed to use cold galvanized sheet tubes as water and gas pipes.

Generally, the galvanized sheets used now are hot-galvanized sheets, and the electrical wire slots are cold galvanized sheets, and the color has a certain difference.

How to distinguish between hot galvanizing and cold galvanizing?

The first difference in the process is:

Hot dip galvanizing is to remove oil from the workpiece, pickling, dipping, drying after dipping into the dissolved zinc liquid for a certain time, can be brought out.

Cold galvanizing, also known as electric galvanizing, is the use of electrolytic equipment to remove oil, pickling the workpiece into the composition of zinc salt solution, and connected to the negative electrode of the electrolytic equipment; A zinc plate is placed on the opposite side of the workpiece and connected to the positive electrode of the electrolytic device, the power supply is switched on, and a layer of zinc is deposited on the workpiece by the directional movement of the current from the positive electrode to the negative electrode.

The difference in appearance: the appearance of electrogalvanizing is smooth and bright, and the electroplating using the color passivation process is also yellow-green as the main color, which is colorful. The coating with white passivation process is bluish white or white is green, and the coating with white passivation process is slightly colorful at a certain Angle with the sunlight. In the corner of the complex workpiece, it is easy to produce "electric burning" and gray, and the zinc layer in this part is thicker. It is easy to form a dead current Angle in the negative corner, resulting in an undercurrent gray area, where the zinc layer is thin. The whole workpiece has no zinc nodules, caking and other phenomena. The appearance of hot-dip galvanizing is slightly rougher than that of electric galvanizing, silver-white, and the appearance is easy to produce process water marks and a little drip nodules, especially at one end of the workpiece. However, the zinc layer of hot dip galvanizing is dozens of times thicker than that of electric galvanizing, and the corrosion resistance is dozens of times that of electric galvanizing.

The difference between galvanized products:

1. The inner and outer walls of hot-dip galvanized steel pipes are galvanized, while the cold galvanized steel pipes are only galvanized on the outer walls;

2. Uniform cold coating, thin thickness; The hot coating is thicker and the thickness is not uniform.

3. The appearance of cold plating is bright, while the color of hot plating is dark.

4. The cold coating has poor corrosion resistance because it is thin; The hot coating is dozens of times thicker than cold galvanized, and forms an infiltration layer with the base metal, which has good corrosion resistance.

5. Cold galvanized steel pipe looks brighter, smooth and flat; The surface of hot-dip galvanized steel pipe is not cold galvanized fine and bright, the surface of hot-dip galvanized steel pipe looks like there are some uneven bumps, and the surface is not shiny, not too reflective.