Optimizing Corrosion Resistance Behavior of Vanadium Conversion Coating on Hot-Dip Galvanized Steel Substrate

Corrosion resistance of galvanized steel increased by optimizing operating conditions (pH, temperature and immersion time) of vanadium conversion coating. In order to evaluate the corrosion behavior of vanadium conversion coating, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used in ۳.۵%wt sodium chloride solution. The results showed the best performance of corrosion resistance at pH=۱.۵, temperature of ۴۵°C with ۱۵ minutes immersion time. The Polarization resistance increased from ۱۰۷۵(Ω.cm۲) for uncoated galvanized steel to ۵۴۲۷۷ Ω.cm۲ in the presence of vanadium conversion coating As well as the corrosion current density decreased from ۶.۳۶×۱۰-۶  A/cm۲ to ۰.۶۱۸۲×۱۰-۶  A/cm۲.

Keywords:

Vanadium Conversion coating (VCC) , Galvanized steel , Electrochemical Impedance Spectroscopy (EIS) , Scanning Electron Microscopy (SEM) , پوشش تبدیلی وانادیم , فولاد گالوانیزه , طیف سنجی امپدانس الکتروشیمیایی(EIS) , میروسکوپ الکترونی روبشی(SEM).