Anti-corrosion properties of stainless steel ۳۰۴L coated with Mn-based thin film and annealed with nitrogen flux exposed to saline solution under various temperatures

AbstractIn this work the corrosion resistance of stainless steel ۳۰۴L coated with Mn-based thin film and post annealed with flow of nitrogen at ۷۲۳ K in ۰.۶ M NaCl solution is reported. The latter was performed at three different solution temperatures of ۲۹۳ K, ۳۱۳ K and ۳۳۳ K. X-ray diffraction analysis was used to determine the crystallographical structure and phases of the annealed samples. Atomic force microscope and field emission scanning electron microscope were employed to determine the morphology of the surface of the samples. Corrosion behavior of the samples in the corroding media was studied by means of electrochemical impedance spectroscopy (EIS) and polarization analysis. Results showed that the sample investigated in the ۰.۶ M NaCl solution at ۲۹۳ K temperature has the highest corrosion resistance than those studied at higher temperatures. The correctness of the EIS results was confirmed by Kramers–Kronig transformation, while fitting of the data (Nyquist and Bode diagrams) to suitable equivalent electrical circuits showed that the highest corrosion enhancement is achieved for the Mn-based/SS۳۰۴L sample in the ۰.۶ M NaCl solution at ۲۹۳ K temperature, resulting in a ۹۰.۵۷% corrosion inhibition enhancement factor (η%). Polarization measurements also showed that this sample has the lowest corrosion current density, lowest corrosion rate and highest corrosion potential with a ۹۶% corrosion inhibition efficiency factor (PE%). Consistent results are achieved for EIS and polarization measurements which are then correlated with the nanostructure of the films using X-ray diffraction and atomic force microscope analyses.

کلیدواژه ها:

corrosion ، Mn thin films ، Potentiodynamic ، Stainless steel ۳۰۴L ، Electrochemical ، Impedance spectroscopy ، Kramers–Kronig transformation