In the production process of using acid zinc plating additives, we sometimes find chromium impurities in the plating solution, so what effect does it have on the plating solution?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product's acid zinc plating additives BZ-528,The influence of chromium impurities on acid zinc plating solution cannot be ignored, especially hexavalent chromium impurities.
Hexavalent chromium is an oxidant, which has a greater impact on the acid zinc plating solution, especially in the low current density region.It will lead to a decrease in current efficiency, and when the hexavalent chromium content is too high, the low current density area has no brightness or no coating.In general, trivalent chromium impurities have little effect on the acid zinc plating solution, but too much trivalent chromium will cause pitting in the zinc coating.
Generally, the trivalent chromium ion in the acid zinc plating solution should be lower than 0.1g/L, and the content of the hexavalent chromium ion should not exceed 3ppm.Once the acid zinc plating solution is polluted by hexavalent chromium, the source of the pollution must be found first (such as the passivation solution is brought in), and the source must be blocked.
Typically, in baths using acid zinc plating additives, hexavalent chromium is treated by:Use insurance powder to reduce hexavalent chromium to trivalent chromium, then adjust the pH of the plating solution to about 6.0, and filter to remove chromium ions after precipitation.If you are interested in acid zinc plating additives, please contact Bigolly customer service to get free samples and detailed technical information!
If you want to know more about zinc plating, you can check "Electroplating encyclopedia".