Chrome-Free Anti-Fingerprint Passivation of Hot-Dip Galvanized Steel Sheet of Household Appliances

In view of the severe pollution of conventional hot-dip galvanizing technology based on chromate conversion fluid,a Cr-free inorganic-organic complex passivation agent was developed by using organosilicon as the major ingredient.Cr-free passivation coating with satisfactory performance was obtained by properly adjusting the passivation parameters.Besides,the relationship among the thickness and uniformity of the passivation coating and passivation parameters was explored,and the effect of the passivation coating thickness on corrosion resistance,fingerprint resistance,electric conductivity and high-temperature discoloration resistance of hot-dip galvanized steel sheet was investigated.It was found that as-prepared Cr-free passivation coating was similar to chromate conversion coating in performance,and its corrosion resistance increased with increasing thickness.However,the electric conductivity,high-temperature discoloration resistance,alkali resistance and solvent resistance of the Cr-free passivation coating were worsened with rising thickness.