Principle and process description of hot galvanizing
1 the introductionHot dip galvanizing, also known as hot dip galvanizing, is a method for steel components to obtain metal coating by immersed in molten zinc solution. In recent years, with the rapid development of high-voltage power transmission, transportation and communications, the protection requirements for steel parts are getting higher and higher.2. Protective properties of hot-dip galvanized layerGenerally, the thickness of electrogalvanizing layer is 5~15um, while that of hot-galvanizing layer is usually more than 35um, even up to 200pm. The coating capability of hot galvanizing is good, the coating is compact, no organic matter inclusion. As is known to all, the mechanism of resistance to atmospheric corrosion of zinc have mechanical and electrochemical protection, under the condition of atmospheric corrosion of zinc layer surface of Zn0, zinc (OH)
2 and alkali carbonate zinc coating, to a certain extent reduce the corrosion of zinc, this layer of protective film (also called white rust) is damaged and will form a new film. When the zinc layer destroyed, endanger the iron matrix, the zinc on the substrate, the electrochemical protection, the standard potential of zinc - 0.76 V, iron the standard potential of 0.44 V, zinc and iron to form the micro batteries, zinc as the anode is dissolved, iron are protected as the cathode. It is obvious that the resistance of hot galvanizing to atmospheric corrosion of matrix metal iron is better than that of electric galvanizing.