Metal plating on the pre threaded fittings

　　Introduction of metal plating screw pipe pre

　　This method is in after degreasing, in addition to the surface of the pipe thread pre oxidized after plating a thin layer of metal coating method, and then dip in molten aluminum in aluminum magnet. In general, the pre - plated metal is copper, because the surface of the steel is very easy to deposit copper. The main technology used for electroplating or electroless plating. In the hot-dip aluminum, copper film dissolved in aluminum, and aluminum liquid can contact with the steel surface, reaction and diffusion and the formation of aluminized layer. The thickness of the copper plating layer is about 3-5 mu m when the bottom layer of pre copper plating is used.

　　French patent 1263450 (1961) proposed, in aluminum before deposition in the surface layer of pipe thread of molten aluminum dissolved weak non-ferrous Jincheng middle layer, and then immersed in molten aluminum aluminum pipe thread. The middle layer in the surface of the pipe thread electroplating method. In order to reduce the solubility of the pre coated metal dissolved in the aluminum liquid, the solubility of the intermediate layer of the metal layer in the molten aluminum is not exceeded. Metals with such properties are chromium, lead, titanium, cobalt, manganese, re, beryllium, bismuth, zirconium, etc.. The main advantage of pre metal plating is easy to obtain compact and good continuity of the aluminized layer. But because the pre plated metal to be more or less dissolved in molten aluminum, which contains a small amount of pre plating metal plating layer in the lower income, the purity of aluminized layer, have a negative impact on the corrosion resistance of coatings.