Classification of galvanized
Galvanizing refers to the surface treatment technology of plating a layer of zinc on the surface of a metal, alloy or other material to play an aesthetic and rust prevention effect.The main method used is hot-dip galvanization.
Zinc is easily soluble in acids as well as alkali, so it is called an amphotropic metal.Zinc changes very little in the dry air.In humid air, a dense alkaline zinc carbonate film is formed on the zinc surface.In the sulfur dioxide, hydrogen sulfide and Marine atmosphere, zinc corrosion resistance is poor, especially in the high temperature and high humidity containing organic acid atmosphere, zinc coating is easy to corrode. The standard electrode potential of zinc is-0.76V, for the steel matrix, zinc coating belongs to the anodic coating, it is mainly used to prevent the corrosion of steel, its protective performance and the coating thickness is very closely related.Zinc coating after passivation treatment, staining or coated with light protective agent, can significantly improve its protection and decorative.
Cold galvanizing, also called electrogalvanizing, is the use of electrolytic equipment after oil, pickling, zinc salt into the solution, and connect the negative electrode of the electrolytic equipment, in the opposite of the zinc plate, connected to the positive electrode of the electrolytic equipment power, using the current from the positive to the negative will deposit a layer of zinc on the pipe, cold plating pipe is first processing after galvanizing.
In the rotating drum equipped with plating, glass ball, zinc powder, water and promoter, the glass ball as impact medium rotates with the drum, friction and hammer on the surface of the plating produce mechanical physical energy. Under the action of chemical promoter, the coated zinc powder "cold welding" to the coating surface, forming a smooth, uniform and detailed coating with a certain thickness.
The main method of steel plate surface galvanizing is hot-dip galvanizing.
Hot galvanizing was developed from older methods and is a hundred and seventy years old since it was used in industry in 1836.However, the hot-dip galvanized industry has been developed on a large scale along with the rapid development of cold-rolled strip steel in the past thirty years.
The production process of hot galvanized plate mainly includes: the original plate pre-plating hot dip post-treatment finished product inspection, etc.According to the habit, according to the different plating treatment method, the hot dip galvanizing process is divided into outside line and annealing inside line annealing.