THE DIFFERENCE BETWEEN HOT-DIP GALVANIZING COLD GALVANIZED

What is galvanization?

Galvanization  galvanizing (also spelled galvanisation  galvanising) is the process of applying a protective zinc coating to steel  iron, to prevent rusting. 

Galvanized steel is to make the steel with better anti-corrosion ability, hardness  longer service life.

2. What is Hot dip galvanized (galvanizing)  cold galvanized (“Cold plated”  “plating”) ?

Hot-dip galvanizing is a chemical treatment, is the electrochemical reaction.

Continuous hot dip galvanizing process: steel → heating → cooling to the temperature galvanized galvanized → cooling 

Hot dip galvanized steel body is hot dip galvanized surface under the condition of its adhesion strong,  easy to fall off, although there hot dip galvanized pipe corrosion phenomenon, but in a very long period to meet technical, health requirements.

Cold galvanizing is the physical address, brush the surface layer of zinc, the zinc layer is easier to fall off. 

The zinc salt solution by electrolysis, to the plating on the coating, generally do  have heating, small amount of zinc.

Cold galvanized zinc is 10-50g/m2, its own corrosion resistance is smaller than hot dip galvanized. Galvanized by a relatively cheaper price.

3. Technological differences

1) First of all, is the difference between process: hot-dip galvanizing is the workpiece degreasing, pickling, dipping, drying liquid immersion in molten zinc certain period of time, can be raised.
2) Also known as electro-galvanized cold galvanizing, is to use electrolysis devices work piece through the degreasing, pickling ingredients post into the zinc salt solution,  connect the anode electrolysis equipment; in place across parts of zinc plate connected to the electrolysis equipment positive, power on, use of current  the cathode to the anode of the directional movement of the workpiece will be deposited in a layer of zinc.
3) Zinc finished the difference: cold galvanized with bright appearance, the thickness of zinc coating of cold galvanizing aspects of hot-dip galvanizing is a few times less. Galvanized corrosion resistance is also several times less.

4. Environmental issues

Fewer emissions of some hot-dip galvanizing.
Galvanized pollutants are mainly artifacts of waste acid pickling.

Cold galvanized pollutants include parts of the waste acid pickling, electroplating waste, liquid waste such as passivation.
Cold galvanized the type  quantity of pollutants discharged are much more than hot dip galvanizing.
Hot-dip galvanizing: hot dip galvanizing process is generally completed after Hemming, when the load is  less than 5mm thick flat steel, the galvanized zinc coating after the average weight of  less than 610 grams / square meter; when the load flat steel thickness less than 5mm, the galvanized zinc coating after the average weight of  less than 460 grams / square meter.