Passive Layer formation on duplex and austenitic stainless steels. Chloride induced modifications in alkaline media

摘要

The present investigation is directed to get an insight into the phenomenon of chloride adsorption on the surface of a passive ferrous alloys (AISI 304L and S31803) and its effects on the evolution of the oxides layers at different times of immersion in a chloride containing solution. Results pointed out that, with increasing time of exposition to chloride ions, the passive film changes from mixed Fe-Cr magnetite-type structure, to a more oxidized iron rich layer. The electrochemical response of the system was analysed by means of cyclic voltammetry and electrochemical impedance spectroscopy (EIS).