cyanide zinc plating uses sodium cyanide as complexing agent, which has good dispersion ability and deep plating ability, mature process, easy control and simple operation and maintenance. Therefore, the process has been used for a hundred years and is still in use today, although the cyanide content in the plating solution is getting less and less. But as we all know, cyanide is a serious drug, and safety and wastewater treatment are very troublesome.
At present, cyanide-free zinc plating mainly includes alkaline zincate zinc plating, acidic ammonium salt and sulfate zinc plating, and slightly acidic potassium chloride zinc plating, each of which has its own advantages and disadvantages.
after zinc plating, in order to improve the corrosion resistance of zinc coating, post-treatment must be carried out, including hydrogen removal, light emission and passivation. Chromic acid is generally used for passivation, but hexavalent chromium does not meet the requirements of environmental protection, so many electroplating solution suppliers have developed trivalent passivation process.