Electrochemical Behaviour of AISI 410 Stainless Steel at Open Circuit Potential in Acidic Solutions

In this study, the electrochemical behaviour of AISI 410 stainless steel at open circuit potential (OCP) in acidic solutions was investigated. For this purpose, the passivation parameters and semiconductor properties of passive films were derived from potentiodynamic polarization, Mott–Schottky analysis and electrochemical impedance spectroscopy (EIS). The potentiodynamic polarization curves suggested that AISI 410 stainless steel showed excellent passive behaviour in HNO3 solutions. Also, the polarization curves showed that the corrosion potential and corrosion current density of AISI 410 stainless steel increased with the increase in the concentration of solutions. For all HNO3 solutions, Mott–Schottky analysis showed two positive slopes in the main passive region (n-type behaviour). Also, this analysis indicated that the donor densities (ND1 and ND2) for the passive films formed on AISI 410 stainless steel are in the range 1021 cm-3 and increased with HNO3 solutions. EIS results showed that the reciprocal capacitance of the passive film is directly proportional to its thickness which increases with decreasing HNO3 concentration. It is thus clear that dilute HNO3 solutions offer better conditions for forming passive films with higher protection behaviour, due to the growth of a much thicker and less defective films.