What is nickel plating? And the type of nickel plating?
What is nickel plating? And the type of nickel plating?
The method of plating a layer of nickel on metals or certain non-metals by electrolysis or chemical methods is called nickel plating. Nickel plating is divided into electroplating nickel and electroless nickel plating. Nickel electroplating is in an electrolyte composed of nickel salt (called main salt), conductive salt, pH buffer, and wetting agent. Metallic nickel is used for the anode, and the cathode is the plated part. Direct current is applied to the cathode (plated part). A uniform and dense nickel plating layer is deposited. Bright nickel is obtained from the bath with brightener, and dark nickel is obtained from the electrolyte without brightener.
Electroless plating is also called electroless plating, and it can also be called Autocatalytic plating [1]. The specific process refers to: under certain conditions, the metal ions in the aqueous solution are reduced by the reducing agent and precipitated on the surface of the solid substrate.
(1) Features, performance and uses of electroplated nickel:
1. The stability of the electroplated nickel layer in the air is very high. Due to the strong passivation ability of metallic nickel, a very thin passivation layer can be quickly formed on the surface
The membrane is resistant to corrosion by the atmosphere, alkali and certain acids.
2. Electroplated nickel crystals are extremely small and have excellent polishing performance. The polished nickel coating can get a mirror-like gloss appearance, and at the same time
It can keep its luster in the air for a long time. Therefore, the electroplated layer is often used for decoration.
3. The hardness of the nickel plating layer is relatively high, which can improve the wear resistance of the surface of the product. In the printing industry, the nickel plating layer is commonly used to increase the hardness of the lead surface.
Due to the high chemical stability of metallic nickel, some chemical equipment also uses thicker plating to prevent corrosion by the medium. Nickel-plated layer
It is also widely used in functional aspects, such as repairing worn and corroded parts, and using brush plating technology for partial electroplating. Electroforming
Process, used to manufacture electroformed plates, record molds and other molds in the printing industry. The thick nickel-plated layer has good wear resistance and can be used as a
Grind the coating. Especially in recent years, composite electroplating has been developed, which can deposit a composite nickel coating with wear-resistant particles. Its hardness and wear resistance are better than those of plating.
The nickel layer is higher. If graphite or fluorinated graphite is used as the dispersed particles, the nickel-graphite or nickel-fluorinated graphite composite coating will have a good
Self-lubricating, can be used as a lubricating coating. Black nickel coatings are also widely used as coatings or decorative coatings for optical instruments.
4. Nickel plating has a wide range of applications. It can be used as a protective decorative coating to protect the base material on the surface of steel, zinc die-casting, aluminum alloy and copper alloy.
The material is not corroded or has a bright decoration effect; it is also often used as an intermediate coating of other coatings, and a thin layer of chromium or a layer of imitation gold is plated on it.
Its corrosion resistance is better and its appearance is more beautiful. In terms of functional applications, the thickness of nickel plating on parts in special industries is about 1~3mm, which can achieve the purpose of restoration.
of. Especially in continuous casting molds, molds on the surface of electronic components, die-casting molds of alloys, and aerospace engines with complex shapes
The manufacturing of components and micro-electronic components has become more and more widely used.
5. In electroplating, due to the many excellent properties of electroplated nickel, its processing volume is second only to electroplated zinc, and its consumption accounts for the total nickel output.
About 10% of it.
(2) Characteristics, performance and use of electroless nickel plating:
1. Thickness uniformity Uniform thickness and good throwing ability are a major feature of electroless nickel plating and one of the reasons why it is widely used.
It avoids the uneven thickness of the electroplated layer due to uneven current distribution. During electroless plating, as long as the surface of the part is in contact with the plating solution, the plating solution will disappear.
Consumed components can be replenished in time, and the thickness of the coating on the plated parts is basically the same, even for grooves, gaps, and blind holes.
2. The plated parts will not permeate hydrogen, and there is no hydrogen embrittlement. There is no need to remove hydrogen after chemical nickel plating.
3. The functions of many materials and parts, such as corrosion resistance and high temperature oxidation resistance, are better than those of electroplated nickel.
4. It can be deposited on the surface of various materials, such as: steel-nickel-based alloy, zinc-based alloy, aluminum alloy, glass, ceramics, plastics, semiconductors, etc.
On the surface of the material, thereby creating conditions for improving the performance of these materials.
5. There is no need for DC motors or control equipment required for general electroplating.
6. The heat treatment temperature is low. As long as the temperature is below 400℃ for different holding time, different corrosion resistance and wear resistance can be obtained, so it is especially suitable
For functional coatings of parts with complex shapes and surface requirements for wear and corrosion resistance, etc.
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