1: what is nickel plating?
Nickel plating is a method of electrolytic or chemical coating of gold on metals or some nonmetals. Nickel plated nickel plating and electroless nickel plating. Electroplating nickel is in the electrolyte composed of nickel salt (called main salt), conductive salt, pH buffer and wetting agent. The anode is plated with nickel and cathode, through direct current, a uniform and compact nickel coating is deposited on the cathode. Bright nickel is obtained from plating bath with brightener, and dark nickel is obtained from electrolyte without brightener. Electroless nickel plating is a method to obtain nickel coating on the surface of materials by autocatalytic reaction in a solution containing metal salts and reductants.
Two: characteristics, properties and uses of nickel plating
(1) the characteristics, properties and uses of electroless nickel plating: 1 the stability of the nickel plating layer in the air is very high. Because of the strong passivation ability of the nickel metal, a thin layer of passivating film can be produced rapidly on the surface, which can resist the corrosion of the atmosphere, alkali and some acid. 2. Nickel electroplating has extremely fine crystals and excellent polishing properties. The polished nickel coating has a mirror-like luster appearance and can maintain its luster for a long time in the atmosphere. Therefore, the electroplating layer is often used for decoration. 3. Nickel coating has high hardness, which can improve the wear resistance of the product surface. In the printing industry, the medium coating is often used to improve the hardness of the lead surface. Due to the high chemical stability of nickel metal, some chemical equipment also commonly used thicker coating to prevent corrosion by the medium. Nickel coating is also widely used in functional aspects, such as repairing worn and corroded parts, using brush plating technology for local electroplating. The electroforming process is used to manufacture electroforming plates, disc molds and other molds for the printing industry. Thick nickel coating has good wear resistance and can be used as wear resistant coating. Especially in recent years, composite electroplating has been developed. Composite nickel coatings with wear-resistant particles can be deposited, and their hardness and wear resistance are higher than those of nickel plating. If graphite or graphite fluorinated graphite is used as a dispersed particle, the obtained nickel graphite or nickel fluorinated graphite composite coating has good self lubrication, which can be used as a lubricating coating. Black nickel coating is also widely used as optical instrument coating or decorative coating. 4 nickel plating has a wide application surface and can be used as a protective decorative coating to protect the substrate from corrosion or light decoration on the surface of steel, zinc, aluminum and copper alloys. It is often used as an intermediate coating for other coatings, and is plated with a thin layer of chromium or a layer of gold imitating layer, and its corrosion resistance is better. The view is more beautiful. In functional applications, nickel plating on parts in special industries is about 1-3 mm thick, which can achieve the purpose of repair. In recent years, there are more and more applications in the continuous casting mold, the surface of the electronic components, the die casting die of the alloy, the complex shape of the aerospace engine components and the manufacture of the micro electronic components. 5 in electroplating, as nickel plating has a lot of excellent properties, its processing capacity is second only to zinc electroplating, and its consumption accounts for about 10% of the total nickel production. (two) the characteristics, properties and uses of electroless nickel plating: 1 uniform thickness uniformity and good plating ability are one of the major characteristics of electroless nickel plating. It is also one of the reasons for the wide application of electroless nickel. Electroless nickel plating avoids the uneven thickness of the electroless plating because of the uneven distribution of current. In electroless plating, as long as the surface of the part is contacted with the plating bath, the ingredients consumed in the bath can be replenished in time. The thickness of the plating parts is basically the same, even if the groove, the slot and the blind hole are also the same. 2. No hydrogen penetration, no hydrogen embrittlement, no need to remove hydrogen after electroless nickel plating. 3. The function of many materials and parts such as corrosion resistance and high temperature oxidation resistance is better than that of electroplating nickel. 4. can be deposited on the surface of various materials, such as the surface of the steel nickel base alloy, zinc based alloy, aluminum alloy, glass, ceramic, plastic, semiconductor and so on, thus creating conditions for improving the properties of these materials. 5. No DC motor or control equipment is required for general electroplating. 6 the heat treatment temperature is low, and the corrosion resistance and wear resistance can be obtained only after different heat preservation time below 400 C. Therefore, it is especially suitable for the functional coating of parts with complex shape, wear resistance and corrosion resistance.
Three: type of nickel plating solution
The main types of nickel plating bath are sulfate type, chloride type, aminosulfonate type, citrate type, fluoroborate type and so on. Among them, the sulfate-type (low chloride) nickel plating solution called Watts (Watts) is the most widely used in industry. Physical properties of nickel coatings obtained in several different nickel plating solutions, as shown in Table 2-3-45. Aminosulfonate type and fluoroborate type are suitable for thick nickel plating or electroforming. Citrate mold is suitable for direct nickel plating on zinc die castings. The cost of these kinds of plating bath is high.
Ordinary nickel plating (dark plating)
1. the ordinary electroplating is also called the dark nickel process. According to the properties and uses of the bath, ordinary nickel plating can be divided into low concentration pre liquid, ordinary bath, Watt liquid and roll plating solution.
Pre-plating solution: Pre-plating can ensure good adhesion with copper-iron substrate and subsequent copper-plating layer.
Ordinary solution: The bath has good conductivity, can be plated at a lower temperature, saving energy, easy to use.
Watt solution: To meet the plating of small parts, but the plating solution must have good conductivity and coverage. |
