100 Questions on Basic Electroplating Knowledge (Part 8)

Separated Letters Gold Metal Logos 36.What is the role of boric acid in nickel plating solution, if the boric acid is insufficient, what will happen? Answer: Boric acid is the buffer of nickel-plating solution, buffering the role of the pH value of the plating solution. When the concentration of 31 g / liter or more, there is a significant effect, but not too high, because the solubility of boric acid at room temperature about 40 g / liter or so. Due to the buffering effect of boric acid, so that the cathode area solution pH value does not produce a sharp change, thus allowing the use of higher cathode current density without precipitation of hydroxides on the cathode. It also has the effect of improving cathodic polarization and plating properties. However, excessive levels of it can reduce cathode current efficiency. The buffering effect is very weak when it is lower than 20g/liter, which makes the pH value of the plating solution change intensify and affects the quality of plating layer, and even makes the plating process impossible. 37.nickel plating, the pH of the electrolyte near the anode and the cathode near the pH of the electrolyte that a high, why? Answer:The pH of the electrolyte near the cathode is higher. This is due to the electrolysis process, the cathode on the precipitation of hydrogen gas and make the pH rise. 2H + + 3 → H2 ↑ Separated Letters Gold Metal Logos 38.After galvanizing the passivation layer, white passivation and color passivation layer that a good corrosion resistance? Answer:The corrosion resistance of a passivated coating after galvanizing is better with a colored passivation than with a white passivation. This is because the passivation white treatment, is already formed in the color passivation film in the bleaching solution to dissolve off…