1. Basic knowledge of galvanizing
Zinc plating is divided into hot-dip galvanized and cold galvanized (electroplating). Hot dip galvanizing is also divided into hot dip galvanizing and zinc permeation. Hot dip galvanizing is a method for steel components immersed into molten zinc liquid to obtain a metal cover layer. It is to immerse the steel parts after the rust removal in the molten zinc solution about 500 degrees C, so that the steel structure is attached to the zinc layer, and then the purpose of anticorrosion is. It is mainly used in the metal structure and facilities of various industries. Since France used hot dip galvanizing in industry in 1836, it has had a history of one hundred and seventy-eight years.
Two. The scientific principle of anticorrosion of hot dip galvanizing
protective function of hot dip galvanizing layer
The mechanism of zinc corrosion resistance is mechanical maintenance and electrochemical maintenance. Under atmospheric corrosion, there are ZnO, Zn (OH) 2 and alkaline zinc carbonate maintenance film on the surface of zinc. The corrosion of zinc can be slowed down to a certain extent. The damage of this layer of maintenance film (also called white rust) will form a new membrane layer. When the zinc layer is seriously damaged and endanger the iron matrix, zinc has electrochemical maintenance to the matrix, the normal potential of zinc is -0.76V, the standard potential of iron is -0.44V, zinc and iron are dissolved in the micro battery as the anode, and iron is maintained as the cathode. Juncheng brand hot-dip galvanized steel pipe surface and exterior zinc coating cover can be good, fine coating, no organic adulteration, is the quality of the first brand galvanized industry.
2. generation principle of zinc coating in hot dip galvanizing
The process of the composition of the hot-dip galvanizing layer is the process of forming an iron zinc alloy between the iron matrix and the outermost pure zinc layer. The surface of the workpiece is made up of an iron zinc alloy layer when hot dipping, which makes it good to combine the iron with the pure zinc layer. The process can be briefly described as: when the iron workpiece is immersed in the molten zinc solution, the zinc and the alpha is formed at the interface first. Iron (Ti Xin) solid melt. This is the matrix metal iron in the solid state dissolved in zinc atoms constitute a crystal, two metal atoms are fused, the gravity between the atoms is relatively small. As a result, when zinc reaches its fullness in the solid melt, the two atoms of zinc and iron are dispersed and dispersed to (or called the infiltrated) iron matrix to relocate in the matrix lattice and gradually form an alloy with iron, and the iron dispersed into the molten zinc solution is composed of the metal intermetallic compound FeZn13 and the bottom of the hot-dip galvanized pan, that is, zinc. Slag. When the workpiece is removed from the zinc leaching solution, the surface forms a pure zinc layer, which is a six party crystal. The iron content is not more than 0.003%.
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