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Overview of Hot Dip Plating Technology
Time：
2017-08-08 00:00
Hot-dip plating, referred to as hot-dip plating, is a method of immersing the metal material to be plated in other liquid metals or alloys with a lower melting point for coating. The basic feature of this method is that an alloy layer is formed between the base metal and the coating metal. Therefore, the hot dip coating is composed of alloy metal and plated metal. The metal materials to be plated are generally steel, cast iron and stainless steel. The low melting point metals used for hot dipping include zinc, aluminum, tin and their alloys.
The hot dip plating process is divided into two categories: flux method and hydrogen reduction method. Among them, the hydrogen reduction method is mostly used for continuous hot-dip coating of steel strips, and the typical Sendzimir method and the U.S. Steel Union method belong to this type of process. The flux method is mostly used for the coating of steel wires and steel structural parts. This method is to apply a layer of flux on the surface of the purified steel before the steel is immersed in the plating pot. During the dipping, the flux layer is decomposed or volatilized by heat, so that the fresh steel surface is exposed and directly contacts with the molten metal. Reaction and diffusion to form a coating.
In the flux method, there are wet method and dry method. Wet method is an earlier method of use. It is a method of dipping purified steel with water flux, directly dipping it into molten metal for hot-dip plating without drying, but covering the molten metal surface with a layer of molten flux. The dry method is to dry by hand in the dip-coating water flux to remove the moisture, and then dip-coating. Due to the simple dry process and the good quality of the coating, most of the hot-dip galvanizing production of steel structural parts adopts the dry method, and the wet method is eliminated one by one.