Film Formation Mechanism of Vanadium Oxide Conversion Coating on Hot-dip Galvanizing Layer

Scanning electron microscope was used to observe the micro morphology of conversion coating in the process of nucleation and growth, the mass of conversion coating was tested by chemical method, and XPS was used to analyze the compound ingredients of the conversion coating. The results show that the vanadium acid salt conversion films were mainly composed of low vanadium compound deposition and vanadium and zinc salt crystals grown up. The weight of conversion film increased with increasing the content of sodium metavanadate within a certain range, which indicated that vanadate passivation had great potential for surface treatment of hot dip galvanized coating.