1. Concept analysis

Hot dip galvanizing: also called hot dip zinc and hot dip galvanizing: it is an effective way of metal anticorrosion. It is to melt the zinc ingot at high temperature, put some auxiliary materials in, and then dip the metal structural parts into the galvanized groove, so that a layer of zinc layer is attached to the metal components, so as to play the purpose of anticorrosion. The advantage of hot dip galvanized is that its anticorrosion ability is strong, the adhesion and hardness of galvanized layer is better, so as to play the purpose of anticorrosion.

Cold galvanizing: it is electric galvanizing, the amount of zinc is small, only 10-50g/m2, is the use of electrolysis to make metal or other materials attached to the surface of a layer of metal film process. The formation of uniform, dense, good bonding metal layer process can play a role in preventing corrosion, improving wear resistance, electrical conductivity, reflective and improve the appearance of the role.

2. Different reaction modes

Hot dip galvanizing is a chemical treatment, which belongs to electrochemical reaction. Hot dip galvanized pipe is made of molten metal and iron matrix reaction to produce alloy layer, so that the matrix and the coating of the two combination

Cold galvanizing is a physical treatment, just brush a layer of zinc on the surface, so the zinc layer is easy to fall off. Hot-dip galvanizing is used in construction.

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3. Technological differences

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

Cold 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 connected to the positive electrode of the electrolytic equipment, switched on the power supply, and a layer of zinc will be deposited on the workpiece by the directional movement of the current from the positive electrode to the negative electrode

4, galvanized product difference

The difference between galvanized products: hot-dip galvanized appearance is not as fine and bright as cold galvanized, uniform coating. But the thickness of zinc layer is dozens of times that of cold galvanizing. Corrosion resistance is also dozens of times that of galvanizing.

Hot dip galvanizing, also known as hot dip zinc, is the method of forming a layer of zinc coating on the surface of the workpiece after oil removal and rust removal, showing a stainless, infiltrated surface, immediately immersed in the plating tank of zinc melting and heating in advance.

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Cold galvanizing is the same after oil removal, rust removal, showing no pollution, infiltrating workpiece hanging into a special plating tank on the cathode, anode with zinc. When DC power is switched on, zinc ions on the anode migrate to the cathode, and discharge on the cathode, so that the workpiece is coated with a zinc layer. Hot dip galvanized coating is thicker, generally 30-60 microns, coating corrosion resistance is higher.

Electrogalvanizing, the workpiece surface is smooth and flat, but because the coating is relatively thin, electrogalvanizing is generally within 5-30 microns, so the corrosion protection time will be shorter. Are used in the indoor use of rust prevention components, such as housing bottom, panel, small size fasteners, etc.

In the suburban environment, the standard hot-dip galvanized rust prevention thickness can be maintained for more than 50 years without repair; In urban or offshore areas, the standard hot-dip galvanized rust protection layer can be maintained for 20 years without repair;

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5. Use difference

Hot dip galvanizing: suitable for outdoor work of steel parts, such as highway fences, power towers, large size fasteners and other "rough" workpiece long-term rust prevention. Older iron water pipes were also hot-dip galvanized.

Galvanizing: used in indoor use of rust prevention parts, such as the bottom of the case, panel, small size fasteners, etc.

6. Price differences

The galvanizing process is faster than other coating construction methods and avoids the time required to apply on the site after installation.

Low treatment cost: the cost of hot dip galvanized rust prevention is lower than that of other paint coating;

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In general, the cost of hot dipping zinc is lower than that of applying other protective coatings for the simple reason that other protective coatings, such as sand painting, are labor-intensive processes, whereas hot dipping zinc processes are highly mechanized, tightly controlled in-plant construction.

Cold galvanizing can only be plated on one side, hot galvanizing must be fully plated. And hot-dip galvanized galvanized layer is generally thicker than cold galvanized, so the price of hot-dip galvanized is higher than cold galvanized

7. Environmental protection issues

Hot dip galvanized square pipe less pollutant emissions, mainly acid waste pickling workpiece.

The pollutants of cold galvanized mainly include waste acid of pickling workpiece, waste electroplating liquid, waste passivation liquid and so on. Discharge type and quantity are much more than hot dip galvanizing.