Progress of Chromium-free Passivation for Zinc Plating

The prevalent chromium-free passivation technology can be classified as inorganic,organic and inorganic-organic complex passivation technologies according to its composition.Each one has its advantages and disadvantages: for inorganic passivation film,heat tolerance shows outstanding but corrosion resistance does not;for organic passivation film,corrosion resistance is good but heat resistance and adhesion are poor;for inorganic-organic complex passivation film,both advantages of inorganic and organic passivations are held but complicated processing due to some applications requiring multistep operation is etisted.This paper introduced some typical chromium-free formulae of inorganic-organic complex passivation technology.The future research of chromium-free passivation should focus on inorganic-organic complex passivation technology as well as its mechanism and improvement of corrosion resistance and adhesion of the passivation films.