Some customers will think that there is a certain potential difference between the two nickel layers of electroplating semi-bright nickel and bright nickel, which can make the coating have good corrosion resistance, why use high-sulfur nickel additives to increase a layer between the coating?
According to the field experience and the characteristics of the product high sulfur nickel additive Ni-320, Bigely Technology has analyzed that generally the potential difference between semi-bright nickel and bright nickel needs to reach 120-130mV in order to achieve better corrosion resistance. And because the semi-bright nickel plating bath is very delicate, a very small amount of pollution of sulfur-containing compounds will make the potential shift negatively, so in order to ensure that the plating layer has a better corrosion resistance, so that the three layers of nickel is more insurance.
Because of high sulfur nickel and semi-bright nickel layer between the potential difference to reach 150mV, such electrochemical protection can make the performance of semi-bright nickel layer significantly improved, but the high sulfur content of the nickel plating layer itself will accelerate the corrosion, so the need to add a layer of higher potential, corrosion resistance is relatively good bright nickel to cover high sulfur nickel plating, so that the potential of the more negative, easy to cause corrosion of high sulfur nickel plating layer to get the protection of the machinery, and also can facilitate the set of chromium, because high sulfur nickel direct set of chromium is more difficult. At the same time can also facilitate the set of chromium, because the high sulfur content of high sulfur nickel plating layer directly set of chromium is more difficult.
Generally the sulfur content of high sulfur nickel plating should be more than 0.15%, the sulfur content of bright nickel plating should be between 0.04% and 0.15%, and the sulfur content of semi-bright nickel plating should be less than 0.005%, so that the process can ensure that the potential difference between the semi-bright nickel and bright nickel plating is between 120-160mV, and that the potential difference between the high sulfur nickel and the bright nickel plating is about 50mV.
It should be noted that the thickness of high-sulfur nickel coating does not need to be thick, thick plating is not good, generally, the thickness of high-sulfur nickel coating only needs to be about 1μm, and the plating time is 2-3min.
Therefore, we use high sulfur nickel additives to add an intermediate layer between semi-bright nickel and bright nickel, which can ensure the potential difference between semi-bright nickel and bright nickel, so that the plating layer has good corrosion resistance. If you are interested in high sulfur nickel additives, please contact Bigely for free samples and detailed technical information.
