Plating knowledge of anti-corrosion treatment of s

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Tianjin Dongxiang hardware nail factory explains the electroplating knowledge of screw anti-corrosion treatment electroplating

Tianjin Dongxiang hardware nail factory explains the electroplating knowledge of screw anti-corrosion treatment


electroplating refers to taking the material or object to be plated as the cathode in a solution containing metal ions to be plated, and through electrolysis, the coating can be obtained on the surface of the substrate. In the process of electrolysis, a chemical reaction takes place at the interface between the electrode and the electrolyte, the electrons released by the anode are oxidized, and the electrons absorbed by the cathode are reduced. Electroplating can cover materials or articles with a relatively uniform coating with good adhesion, so as to change their surface characteristics and appearance, so as to achieve the purpose of material protection or decoration. Direct current (low voltage, high current) shall be used for electroplating, and the current density and power on time shall be properly controlled to obtain the required coating thickness

corrosion resistant coatings are usually made of zinc, cadmium, copper, nickel and other metals or zinc nickel, nickel tin, nickel copper, copper zinc and other alloys. According to the different electrode potential when the coating forms a couple with the base metal, it can be divided into anodic coating and cathodic coating. In corrosive media, the potential of anodic coating is more negative than that of the base metal, such as zinc plating or cadmium on steel. When the coating is damaged, the coating will be dissolved as an anode, which has electrochemical protection for steel, that is, "sacrificial" protection. The thicker the coating, the greater the protection

the potential of cathodic coating is corrected compared with that of the base metal, such as aluminum, copper and nickel plating on steel. When the coating is damaged, the coating will accelerate the corrosion of the exposed part of the base metal, and can only protect it when it is completely impermeable. Therefore, the coating should pay attention to its tightness and no damage, and the protective ability determines its porosity. The porosity is low, and the protective effect is large. Its anti-corrosion effect is to use the coating to isolate the external environment, The corrosive medium cannot penetrate into the base metal. Such as Tianjin machine screw

hot dip coating

hot dip coating is a method of immersing the plated part in molten metal to form a coating on its surface. The melting point of hot-dip coating metals is much lower than that of base metals, such as zinc, aluminum, lead and their alloys. A fairly thick coating can be obtained by hot-dip method, which is usually thicker than similar electroplating, and the hot-dip coating is rarely porous. The hot-dip coating generally has better corrosion resistance than the same electroplating coating. In the same corrosive environment, the hot-dip coating has a long service life and strong adhesion. However, this method is difficult to control the thickness of the coating. Generally, the coating thickness of more than 50g/m2 is easier to obtain by hot-dip plating, while the coating thickness of less than 50g/m2 can be obtained economically by electroplating. A successful hot-dip coating method must combine the underlying metal with the coating metal to form an alloy. At least to a certain extent, the coating obtained by the hot-dip coating method is not only the coating of the components used. In the crystalline structure, the hot-dip coating has at least two layers, one is the inner layer of gold diffusion layer, and the other is the outer layer of coating. The outer layer basically has the same properties as when the applied components are not used as coating, and the inner layer of diffusion layer is often hard and brittle, After bending, it may peel or crack, so the treated parts cannot be excessively deformed. The deformation procedure that can be endured by the treated parts determines the metal, coating and other factors used. Therefore, products are often hot dipped after deformation processing

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