Study on Molybdate Complex Passivation Bath for Galvanized Steel

In order to enhance the corrosion resistance of galvanized steel,a new chromate-free complex passivation bath using molybdate,phosphate,phytic acid and organic silane as principal constituents and other additives was prepared.The additives of the bath were optimized by neutral salt spray tests(NSS).The corrosion resistance and mechanism of the passivation film were studied by electrochemical impedance spectra(EIS),SEM and AFM were used to analyze the appear element buildup and morphology.The results showed that the process was simple with lower cost;corrosion resistance of zinc coating increased obviously after it was treated with the complex passivation bath,and the corrosion area proportion of treated samples was less than 5% after uninterrupted 96 h NSS.