Development Status of Chromium-free Conversion Coating Technology

Chromate conversion coatings have been gradually replaced by chromium-free conversion coatings for the environmental demand.The formation mechanism and development of chromium-free conversion coatings,such as oxyacid salt,zirconium salt and titanium salt,phytic acid,rare earth,silane were introduced in this paper.With the development of technology,chromium-free conversion coatings would obtain more and more attention and be applied to more fields.