A Study of Chromium-Free Light Blue Passivation Process for Electrogalvanized Coating

The chromium-free light blue passivation process for electrogalvanized coating was studied by using a passivation solution compounded of sodium molybdate and organic acids.The passivation solution is good in stability,lower in cost,easy to operate,can form a bright and uniform light blue passivation coating on the surface of galvanized steel.The corrosion resistance of the passivation coating was tested with dropping,salt solution soaking and electrochemical methods.The results show that the corrosion resistance of the new chromium-free passivation coating is equal to that of chromate passivation coating.The coating is uniform and fine with no micropores and cracks.It can be expected that this new passivation technology will be able to substitute for chromate passivation technology in passivation of electrogalvanzied coating.