The use of nickel sealing additives can effectively improve the corrosion resistance of nickel coating.This is because the solid particles on the surface of the composite nickel plating layer are non-conductive when the chromium layer is deposited, so the chromium layer cannot be deposited on these particles, and a large number of micropores will be formed on the chromium layer.These micropores can remove the huge internal stress in the coating, thereby reducing the stress corrosion of the coating.So, what points should be paid attention to when using nickel sealing additives?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product nickel sealing additives Ni-351,there are four main points:
1. Control of pH value of plating solution.When the pH value of the plating solution is low, the content of particles on the coating layer is too high, and "reverse light" will appear;When the pH value is high, the content of particles in the coating is not enough, and burrs will be generated.The pH value of the plating solution should be controlled within the process range. For example, the pH value of Bigolly's Ni-351 nickel sealing additive should be controlled at 3.8~4.2.
2. The control of the cathode current density.The relationship between the cathode current density and the volume percent of particles contained in the coating depends on the rate of metal deposition and the rate at which the cathode adsorbs the particles.Within the range of process parameters, the current density has little effect on the particle volume percentage of the coating. For example, when using Bigolly's Ni-351 nickel sealing additive, the current density should be controlled at 4~6A/dm2.
3. Control of stirring intensity.The stirring force has a great influence on the coating.The air in which the bath is stirred must be purified, and no solid contaminants or oils are allowed to enter the bath.Automatically controlled pulsating air agitation can be used to increase the number of micropores in the low zone.
4. Control of coating thickness.Generally, the thickness of the nickel sealing layer is 0.1μm to show the effect of the nickel sealing layer. In order to achieve a better effect, the thickness of the sealing nickel is recommended to be 1~3μm.And the chromium layer behind the nickel sealing layer should not be too thick, just 0.25μm.
Therefore, in order to obtain a nickel-sealed coating with better performance when using nickel sealing additives, we should pay attention to the above four points.If you are interested in nickel sealing additives,please contact Bigolly customer service, you can get free samples and detailed technical information!
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