The method of plating a layer of nickel on metal or some non-metals by electrolysis or chemical method is called nickel plating. Nickel plating is divided into electroplating nickel plating and electroless nickel plating. Nickel electroplating is in an electrolyte composed of nickel salt (called main salt), conductive salt, pH buffer, and wetting agent. The anode is made of metallic nickel, and the cathode is a plated piece. Direct current is applied to the cathode (plated piece). Deposit a uniform, dense nickel coating. Bright nickel is obtained from the bath with brightener, and dark nickel is obtained from the electrolyte without brightener.
The stability of the electroplated nickel layer in the air is very high. Due to the strong passivation ability of metal nickel, a very thin passivation film can be rapidly formed on the surface, which can resist the corrosion of the atmosphere, alkali and certain acids.
The electroplated nickel crystals are extremely fine and have excellent polishing performance. The polished nickel coating achieves a mirror-like glossy finish while maintaining its luster for long periods of time in the atmosphere. Therefore, electroplating is often used for decoration.
The hardness of the nickel coating is relatively high, which can improve the wear resistance of the surface of the product. The nickel coating is commonly used in the printing industry to improve the hardness of the lead surface. Due to the high chemical stability of metallic nickel, thicker nickel plating is also commonly used in some chemical equipment to prevent corrosion by the medium. Nickel plating 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, record molds and other molds in the printing industry. Thick nickel plating has good wear resistance and can be used as a wear-resistant coating. Especially in recent years, composite electroplating has been developed, which can deposit a composite nickel coating with wear-resistant particles, and its hardness and wear resistance are higher than that of nickel coating. If graphite or fluorinated graphite is used as the dispersed particles, the obtained nickel-graphite or nickel-fluorinated graphite composite coating has good self-lubricating properties and can be used as a lubricating coating. Black nickel coating is also widely used as a coating or decorative coating for optical instruments.
