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Abstract
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The passivation behavior of AISI 430 ferritic stainless steel was investigated in concentratedalkaline solutions in relation to several test parameters, using electrochemical techniques.Increasing solution pH (varying from 11.5 to 14.0) leads to an increase in the corrosion rateof the alloy. Mott–Schottky analysis revealed that passive films formed on AISI 430 ferriticstainless steel behave as n-type semiconductor and the donor densities increased with pH.Electrochemical impedance spectroscopy (EIS) results showed that the reciprocal capaci-tance of the passive film is directly proportional to its thickness, which decreases with pHincrease. The results revealed that for this ferritic stainless steel in concentrated alkalinesolutions, decreasing the solution pH offers better conditions for forming passive films withhigher protection behavior, due to the growth of a much thicker and less defective film.
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