Difference between cold and hot dip galvanizing.
The first difference in the process is: hot-dip galvanizing is the processed parts are degreased, pickled, impregnated, dried and then added to the molten zinc solution, cold galvanized parts are mainly immersed in molten zinc and thus a method of obtaining a metal coating. The principle is mainly hot-dip galvanized coverage ability, the coating is also more dense, no organic inclusions. We all know that the mechanism of zinc's resistance to atmospheric corrosion consists of mechanical protection as well as electrochemical protection. In some corrosive environments, the surface of the zinc layer is mainly ZnO, Zn and alkaline zinc carbonate layer of protective film, which to a certain extent to slow down the corrosive properties of zinc, this protective film is destroyed after the formation of a new film. When the zinc layer is severely damaged and the iron matrix is threatened, cold galvanizing is also known as electro-galvanizing. The main use of electrolytic equipment to degrease and pickle the workpiece into a solution containing zinc salts, and then connected to the negative electrode of the electrolytic equipment; the zinc plate is placed on the workpiece, connected to the positive electrode of the electrolytic equipment, connected to the power supply, and a layer of zinc is deposited on the workpiece.
How to distinguish between cold galvanized and pre-hot-dip galvanized?
The difference between galvanized products: hot-dip galvanized appearance is not as delicate and bright as cold galvanized, but the thickness of the zinc layer is dozens of times that of cold galvanized. Anti-corrosion properties are electro-galvanized zinc layer is thicker, the surface of the plating is generally visible to the naked eye can be identified as bright flakes, the surface can be touched by hand. Feel a certain degree of roughness, the appearance of bright silver color. Hot-dip galvanizing production temperature is too high, the appearance is mainly gray, knocking will make the zinc-iron alloy layer of small pieces appear to fall off.
Cold galvanized general surface is smoother, silver gray, no sequins.
