Electroless nickel plating technology is a method to obtain the coating by the autocatalytic reaction of metal salt and oxidizer on the workpiece surface. Up to now, electroless nickel plating is one of the fastest growing surface treatment processes overseas and is the most widely used. The efficient development of electroless nickel plating is determined by its excellent process characteristics.
First, the process characteristics of electroless nickel plating layer
1. Uniformity of thickness
Uniform thickness and uniform plating ability are one of the main characteristics of electroless nickel plating, and also one of the reasons for its wide use. Electroless nickel plating prevents uneven thickness due to uneven current spread. The whole parts, especially the parts with complicated shapes, have a large difference in plating thickness. In the corners of the parts and near the anode, the coating is thick, and in the inner surface or far from the anode, the coating is very thin and can not even be plated. During electroless plating, as long as the surface of the part touches the plating solution, the components consumed in the plating solution can be replenished in time, and the coating thickness of each part is basically the same, even if it is the groove, gap and buried hole.
2. No hydrogen embrittlement problem
Electroplating is the use of a power source to convert nickel cations into metal nickel deposited on the anode. The chemical reduction method is to restore the nickel cation to metal nickel and deposit it on the surface of the matrix metal. The experiment shows that the inclusion of hydrogen in the coating has nothing to do with the chemical oxidation reaction, but has much to do with the electroplating standard. In general, the hydrogen content in the coating increases with the increase of the current intensity.
In nickel electroplating solution, except for a small part of the hydrogen is due to NiSO4 and H2PO except 3 reaction, most of the hydrogen is caused by hydrolysis caused by electrode reaction when the poles are energized. In the anode reaction, with the formation of a large amount of radon, the radon gas on the negative electrode and the metal Ni-P alloy are deposited at the same time to produce (NI-P)H, which is stuck in the sedimentary layer, because the negative surface layer produces too much atomic hydrogen, and part of the adsorption generates H2. If there is no time for adsorption, leave it in the coating. Part of the hydrogen in the coating diffuses into the base metal, while the other part of the hydrogen accumulates in the base metal and the coating defects to produce radon gas groups. The air mass is very pressurized. Under the influence of pressure, the defect causes cracks, and the rupture source is generated under the action of stress, resulting in hydrogen embrittlement. Hydrogen permeates not only into the base metal, but also into the coating. It is reported that nickel plating should be 400℃×18h or 230℃×48h after heat treatment, the hydrogen in the coating can be basically eliminated, so nickel plating is difficult to remove hydrogen, and electroless nickel plating does not need to remove hydrogen.
3. Many materials and many functionssuch as corrosion resistance and heat reduction, are reflected in the surface layer of materials and components
In general, some electroless nickel plating layers with unique functions can replace the overall solid core material in other ways, and can also replace valuable raw material parts with cheap substrate electroless nickel plating. Therefore, the economic benefits of electroless nickel plating are particularly large.
4. It can be deposited on the surface of steel nickel base alloy, zinc base alloy, glass, porcelain, plastic, semiconductor and other materials to improve the performance of these materials.
5. Do not need the DC motor or control system required for general electroplating, the heat treatment temperature is low, as long as the holding time is different under 400℃, you can get different corrosion resistance and wear resistance. Therefore, there will be no heat treatment deformation problem, especially suitable for processing some complex shapes, surface wear resistance, corrosion resistance parts.
The chemical deposition layer is thin and controllable, the process is simple, the operation is simple, the temperature is low, the cost is lower than other surface treatment and maintenance, suitable for small and medium-sized factories or small batch production.
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Electroless nickel plating is a common process in metal surface treatment. At present, the application of electroless nickel plating is very wide, in electronic components, mechanical processing, mold, automotive industry and other industries, can see the shadow of electroless nickel plating
1. Electroless nickel plating can effectively improve the performance of electronic products. After electroless nickel plating metal product components, wear resistance and corrosion resistance can be significantly improved. Especially in the mechanical hard disk, pcb circuit board, resistance components, metal components, etc., after electroless nickel plating components, can effectively improve the corrosion resistance, wear resistance and other properties.
2. Electroless nickel plating can effectively improve the life of mechanical manufacturing parts. After electroless nickel plating mechanical parts, such as: transmission chain, gear, hydraulic shaft, etc., can effectively improve its wear resistance and corrosion resistance, get a longer service life.
3. Electroless nickel plating can effectively improve the stability of cars and motorcycles. After electroless nickel plating, the wear resistance and corrosion resistance of the components have been greatly improved. In particular, the wear resistance and corrosion resistance of radiators, shock absorbers, screws, etc., are effectively improved, and finally, the stability of cars and motorcycles is improved.