A customer inquired and found that during the process of using semi bright nickel additives, it was found that the semi bright nickel layer of the same workpiece was plated in the same plating bath, and there was color difference between the nickel layers plated in the morning and afternoon. However, the parameters such as plating solution temperature, pH value, and current density were all normal. What is the reason for this?
Based on on-site experience and the characteristics of the semi bright nickel additive Ni-331 in the product, Bigley Technology conducted an analysis, which was mainly caused by the low concentration of boric acid in the plating solution, as Bigley's customer solution had experienced such a phenomenon.
Once, a customer reported that there was a color difference in the coating of nickel plated workpieces, and the pH value of the nickel plating solution fluctuated greatly. It was necessary to add more sulfuric acid every morning when starting the machine, and the pH value of the plating solution increased by about 0.5 for a day of production. After analyzing the plating solution on site, the engineer found that the concentration of boric acid in the plating solution was only 21.5g/L, so the large fluctuation in the pH value of the plating solution was caused by boric acid.
When the engineer adjusted the concentration of boric acid to 40g/L, the pH value of the plating solution was relatively stable. After a day of production, the fluctuation of pH value did not exceed 0.2, and the color difference problem of the workpiece coating was solved.
Insufficient concentration of boric acid can cause the plating solution to lose its buffering effect, causing significant fluctuations in the pH value of the plating solution, resulting in a significant difference in pH values between the morning and afternoon plating solutions. When the pH value of the plating solution is too high, there are alkaline compounds in the nickel layer, and the coating appears light brown yellow. Sometimes, white mist and unclean color strips may also appear. After adding boric acid to the plating solution and adjusting the pH value, there will be no such color difference in the workpiece coating.
So, in the process of using semi bright nickel additives, we should pay attention to controlling the concentration of boric acid to avoid color difference in the workpiece coating and reduce the occurrence of faults. If you are interested in semi bright nickel additives, please contact Bigley customer service for free samples and detailed technical information!
If you want to learn more about nickel plating, you can click to view the "Common problem".