- Sep 25, 2018 -
For a long time, the nitrate passivation process has been widely used in the passivation treatment of electroplated zinc layer. The chromium in the oxide film after passivation exists in the form of trivalent and hexavalent, but hexavalent chromium is highly toxic and carcinogenic. Serious pollution of the environment. With the increasing awareness of environmental protection, the application of hexavalent chromium in the electroplating industry has been gradually restricted by strict restrictions. In particular, the EU's restrictions on hexavalent chromium have had a profound impact on the surface treatment industry. A trend has formed in the automotive industry. Therefore, there is an urgent need to research and develop a non-toxic or low-toxic substance to replace the chromate passivation process. In recent years, there have been many research reports on the substitution of chromate passivation at home and abroad. Trivalent chromium passivation has similar properties to hexavalent chromium passivation in many respects, but the toxicity is only one percent of hexavalent chromium. Chromium passivation has made positive progress and has been applied to production gradually, with good results, and will become the new process most likely to be accepted.