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What is the difference between hot galvanizing and cold galvanizing
Release time:2020-08-10 10:47:20      The number of clicks:57

The difference between hot-dip galvanizing and cold-dip galvanizing is: hot-dip galvanizing is a chemical treatment, which is an electrochemical reaction. Cold galvanizing is a physical treatment, only a layer of zinc is brushed on the surface, so the zinc layer is easy to fall off. Hot-dip galvanizing is often used in building construction.

Zinc is soluble in acid and alkali, so it is called amphoteric metal. Zinc hardly changes in dry air. In humid air, a dense basic zinc carbonate film will be formed on the zinc surface.

In atmospheres containing sulfur dioxide, hydrogen sulfide, and marine atmospheres, zinc has poor corrosion resistance, especially in high temperature and high humidity atmospheres containing organic acids, zinc coatings are easily hot-dip galvanized, which is also called hot-dip galvanizing. Melt the zinc ingot at high temperature, put in some auxiliary materials, and then immerse the metal structure in the galvanizing tank, so that a zinc layer is attached to the metal component.

The advantage of hot-dip galvanizing lies in its strong anti-corrosion ability, and good adhesion and hardness of the galvanized layer. Cold galvanizing is a physical treatment, just brushing a layer of zinc on the surface, so the zinc layer is easy to fall off. Hot-dip galvanizing is often used in building construction. Continuous hot-dip galvanizing process: steel → heating → cooling to galvanizing temperature → galvanizing → cooling.

Galvanizing is to immerse the workpiece in the molten zinc solution for a certain period of time after degreasing, pickling, dipping, and drying. Environmental issues: Hot-dip galvanizing emits fewer pollutants.

Cold galvanizing is also called electro-galvanizing, which is a process of anti-corrosion treatment of workpiece surface through electrochemical principles. Cold galvanizing is the use of electrolysis equipment to degreasing and pickling the workpiece into a solution of zinc salt, and connect it to the negative electrode of the electrolysis device; place a zinc plate on the opposite side of the workpiece, connect it to the positive electrode of the electrolysis device, and turn on the power , Using the directional movement of the current from the positive electrode to the negative electrode, a layer of zinc will be deposited on the workpiece.

The pollutants of cold galvanizing mainly include waste acid, electroplating waste liquid, waste passivation liquid and so on. The types and quantity of pollutants discharged by cold galvanizing greatly exceed those of hot galvanizing.


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