Effect of Current Density of Electrodeposition on Microstructure and Corrosion Behavior of Mn-Co-CeO۲ Coating on AISI ۴۳۰ Steel

AISI ۴۳۰ ferritic stainless steel is used as interconnects in solid oxide fuel cells. In order to improve the corrosion resistance of this steel under operation conditions of solid oxide fuel cells, a protective and conductive coating layer on the interconnects can be used. In this research, AISI ۴۳۰ ferritic stainless steel was coated with electrolytic with manganese, cobalt and cerium oxide under different density densities (۴۰۰, ۵۰۰, ۶۰۰ and ۷۰۰ mA/cm۲). The coated specimens were studied by scanning electron microscopy (SEM) with X-ray diffraction spectroscopy (EDX). In order to investigate the corrosion behavior of the coatings, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests was used in aqueous NaCl solution of ۳.۵%. The results showed that with increasing the current density, the coating became even more uniform. The results of electrochemical polarization showed that the coating produced at a current density of ۶۰۰ mA/cm۲ has a better corrosion resistance (۰.۱۸۶ μA.cm۲) than the coatings produced at current density of ۴۰۰ (۲.۰۶ μA.cm-۲), ۵۰۰ (۱.۷۶۷ μA.cm-۲) and ۷۰۰ (۱.۰۲ μA.cm-۲). Also the results of electrochemical impedance spectroscopy showed that the capacity of coating produced at current density of ۶۰۰ mA/cm۲ (۱.۴۷E-۴ Ω-۱cm-۲Sn) is lower in comparison with the coatings produced at current density of ۴۰۰ mA/cm۲ (۲.۵E-۴ Ω-۱cm-۲Sn), ۵۰۰ mA/cm۲ (۱.۶E-۴ Ω-۱cm-۲Sn) and ۷۰۰ mA/cm۲ (۲.۱E-۴ Ω-۱cm-۲Sn) which indicating better corrosion resistance of produced coating at current density of ۶۰۰ mA/cm۲.

کلیدواژه ها:

Microstructure ، Potantiodynamic polarization ، Electrochemical impedance spectroscopy ، Current density ، AISI ۴۳۰ ferritic stainless steel ، Mn-Co-CeO۲ coating ، میکروساختار ، پلاریزاسیون پتانسیودینامیک ، امپدانس الکتروشیمیایی ، دانسیته جریان ، فولاد زنگ نزن فریتی AISI ۴۳۰ ، پوشش Mn-Co-CeO۲.