In the process of galvanizing production, sometimes when the workpiece is passivated with trivalent chromium color passivator after galvanizing, the product appears uneven color and mottled appearance, which will seriously affect the appearance and performance of the product. How should the situation be resolved?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product galvanized trivalent chromium color passivator BZ-208, mainly for the following three reasons:
1. The pH value of the passivation solution is too high. The pH of the passivation solution should be adjusted to within the normal range with nitric acid.When nitric acid is used, it should be added in small amount and several times to avoid adjusting with sodium hydroxide when the pH value is too low.
2. The use time of the passivation solution is relatively long, and the impurities are relatively high.It is necessary to drain about 1/5 of the passivation solution, and then replenish the original solution to make the concentration within the process range. If the appearance of the product does not improve significantly after the update, consider rebuilding the bath.
3. The concentration of trivalent chromium in the passivation solution is low.Through titration analysis, supplement an appropriate amount of passivation solution stock solution to maintain the concentration of trivalent chromium in the passivation agent within the process range.
Therefore, when we use galvanized trivalent chromium color passivator, we must control the pH of the passivation solution and the concentration of trivalent chromium, and update the passivation solution if necessary, which can effectively avoid the uneven color and mottled phenomenon of the coating, reduce the failure rate.If you are interested in galvanized trivalent chromium color passivator, please contact Bigolly customer service, you can get free samples and detailed technical information!
If you want to know more about copper plating, you can check "common problem".