Advancement in Chromium-free Composite Conversion Coating on Hot-dip Zinc Coating

To guide the development of composite chromium-free conversion coating technology in hot-dip galvanzing, the development path and research status of the domestic and foreign composite chromium-free conversion coating on hot-dip zinc coating are summaried, the protective characteristics of composite chromium-free conversion coating are described, the affecting factors of corrosion resistance are analysed, and the research methods are evaluated.