What Is Nickel Plating?

A method of electroplating or chemically plating a metal or some non-metal with a layer of nickel is called nickel plating. Nickel plating is divided into electroplated nickel and electroless nickel plating. Electroplated nickel is an electrolyte composed of a nickel salt (referred to as a main salt), a conductive salt, a pH buffering agent, and a wetting agent. The anode is metallic nickel, and the cathode is a plated part. Direct current is applied to the cathode (plated part). Deposit a uniform, dense nickel coating. Bright nickel was obtained from the plating solution with the brightener added, and dark nickel was obtained from the electrolyte without the brightener added.

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(I) Characteristics, properties 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.

Membrane, can resist the corrosion of the atmosphere, alkali and some acids.

2. The electroplated nickel crystal is extremely small and has excellent polishing performance. Polished nickel plating gives a mirror-like glossy appearance while

It can maintain its luster in the air for a long time. Therefore, the plating layer is often used for decoration.

3. The hardness of nickel plating is relatively high, which can improve the wear resistance of the product surface. In the printing industry, nickel plating is commonly used to increase the hardness of lead surface.

Because metal nickel has high chemical stability, some chemical equipment also commonly uses thicker nickel coatings to prevent corrosion by the medium. Nickel plating

It is also widely used in functional aspects, such as repairing worn and corroded parts, and using brush plating technology for local plating. Using electroforming

Process used to make electroforms, record dies, and other dies in the printing industry. Thick nickel-plated layer has good abrasion resistance and can be used as

Abrasive coating. Especially in recent years, composite electroplating has been developed, which can deposit a composite nickel plating layer with wear-resistant particles. Its hardness and wear resistance are better than plating

The nickel layer is higher. If graphite or fluorinated graphite is used as the dispersed particles, the obtained nickel-graphite or nickel-fluorinated graphite composite coating has good properties.

Self-lubricating, can be used as a lubricating coating. Black nickel plating is also widely used as a plating or decorative plating for optical instruments.

4. Nickel plating has a wide range of applications. It can be used as a protective decorative coating to protect the substrate on steel, zinc die-casting, aluminum alloy and copper alloy surfaces.

The material is not subject to corrosion or bright decoration; it is also often used as an intermediate coating for 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, nickel plating on parts of special industries is about 1 ~ 3mm thick, which can achieve repair purposes.

of. Especially in continuous casting molds, molds on the surface of electronic components, alloy die-casting molds, and aerospace engines with complex shapes

Components and microelectronic components are becoming more widely used.

5. In electroplating, because electroplated nickel has many excellent properties, its processing volume is second only to electroplated zinc, and its consumption accounts for the total nickel output.

About 10%.

(B) the characteristics, performance and use of electroless nickel plating :

1. Thickness uniformity Thickness uniformity and good plating ability is a major feature of electroless nickel plating and one of the reasons for its wide application.

The uneven thickness of the electroplated layer due to the uneven current distribution is avoided. In electroless plating, as long as the surface of the part is in contact with the plating solution,

The consumed components can be replenished in time, and the thickness of the plating at the plated parts is basically the same, even for grooves, gaps and blind holes.

2. The plated parts will not permeate hydrogen, there is no hydrogen embrittlement, and there is no need to remove hydrogen after chemical nickel plating.

3. Many materials and components have better functions such as corrosion resistance and high temperature oxidation resistance than nickel plating.

4 , can be deposited on the surface of various materials, such as: steel nickel-based alloy, zinc-based alloy, aluminum alloy, glass, ceramics, plastics, semiconductors and other materials

Materials on the surface, thus creating conditions for improving the performance of these materials.

5. No DC motor or control equipment required for general plating is needed.

6. The heat treatment temperature is low. As long as the temperature is below 400 , different corrosion resistance and wear resistance can be obtained.

Functional coatings for parts with complex shapes and surfaces that require wear and corrosion resistance

The types of nickel plating solution are mainly sulfate type, chloride type, sulfamate type, citrate type, and fluoroborate type. Among them, the sulfate type (low chloride) is called Watts (

Compared with electroplating, the history of nickel plating solution is relatively short. Its actual application to industry in foreign countries is only a matter of the late 1970s and early 1980s. In 1844, A. Wurtz discovered that metal nickel can be reduced by hypophosphite from an aqueous solution of a metal nickel salt and deposited. The true discovery of electroless nickel plating technology and its application so far is in 1944, the discovery of A. Brenner and G. Riddell of the National Bureau of Standards, which clarified the catalytic characteristics of the coating formation, and found the deposit of non-powdered nickel. The method makes the industrial application of electroless nickel plating technology ^[1] possible. However, the electroless nickel plating solution was extremely unstable at that time, so it had no practical value in the strict sense. The application of the electroless nickel plating process is nearly ten years later than the results of laboratory research. After the Second World War, the American General Transport Company became interested in this process. They wanted to plate nickel on the inner surface of the caustic soda cans, but ordinary electroplating methods could not be achieved. Phosphor alloy technology, published many patents. In 1955, their first experimental production line was created, and a commercially useful electroless nickel plating solution was made. This chemical nickel plating solution has a trade name of "Kanigen". Electroless nickel plating has become a very mature high-tech abroad, especially in the United States, Japan, and Germany, and has been widely used in various industrial sectors. The industrial production of electroless nickel plating in China started late, but has developed very rapidly in recent years. Not only have a large number of papers been published, but also a national electroless plating conference has been held. There were already more than 300 manufacturers, but this number should be extremely conservative at the time. It is speculated that the total size of the domestic electroless nickel plating market should be around 30 billion yuan each year, and develop at a rate of 10% to 15% per year.