Galvanizing process

Galvanizing refers to a surface treatment technology that coats the surface of metal, alloy or other materials with a layer of zinc for aesthetics and rust prevention. The function of galvanizing is to prevent steel from rusting, and steel is easily corroded in the natural atmosphere. Zinc is not easy to change in dry air. In a humid environment, a dense zinc carbonate protective film will be formed on the surface, which can protect steel.

There are generally three galvanizing processes and methods: mechanical galvanizing, hot dip galvanizing and cold galvanizing:

1. Mechanical galvanizing. The mechanical galvanizing process is a relatively traditional galvanizing process. It is placed in a rotating drum filled with plated parts, glass balls, zinc powder, water and accelerator. The glass balls as the impact medium roll with the The barrel rotates, friction with the surface of the plated part and hammering to generate mechanical and physical energy. Under the action of the chemical accelerator, the coated zinc powder is "cold welded" to the surface of the plated part to form a smooth, uniform and delicate layer with a certain Thickness of coating. 2. Hot-dip galvanizing, also called hot-dip galvanizing, first pickles the plated parts to remove the oxide layer on the surface of the plated parts, providing conditions for the firm adhesion of the coating, and then cleans with plating agents to further remove impurities on the surface of the plated parts, and then Put it into the zinc liquid in the hot dip plating tank and soak it to make the zinc liquid evenly and densely adhere to the plated parts to form a coating. Hot-dip galvanizing was developed from the older hot-dip method. It has a history of 140 years since France applied hot-dip galvanizing to industry in 1836. The hot-dip galvanizing industry has developed on a large scale in the past thirty years with the rapid development of cold-rolled strip steel. With the discovery of industry, hot-dip galvanized products have been used in many fields, and are widely used in power towers, communication towers, railways, highway protection, street light poles, marine components, building steel structure components, substation ancillary facilities, light industry, etc. 3. Cold galvanizing, also called electro-galvanizing, involves removing surface oil and dust, pickling, and cleaning to remove impurities on the surface of the plated parts, and then placing them into a zinc salt solution. At the same time, a zinc plate is placed opposite the plated parts, and then the plated parts are connected to The negative electrode of the electrolysis equipment and the zinc plate are connected to the positive electrode of the electrolysis equipment. The power is turned on, and the zinc layer is attached to the plated parts through the electrolysis reaction. Because zinc is not easy to change in dry air, but in humid air, a very dense zinc carbonate film can be formed on the surface, which can effectively protect the interior from corrosion. And when the coating is damaged for some reason and a small base is exposed, the zinc and the steel base form a micro-battery, so that the fastener base becomes the cathode and is protected.

As new processes continue to mature, mechanical plating has been eliminated. The commonly used processes are hot dip galvanizing and cold galvanizing. Among them, hot dip galvanizing is the most commonly used.