APPLICATION OF A REDOX KINETIC-STUDY TO T HE CHARACTERIZATION OF THE ELECTROCHEMICAL PROPERTIES OF THE PASSIVE FILM ON A STAINLESS-STEEL

The steady-state redox currents of the Fe3+/Fe3+ couple were measured on an AISI 304 stainless steel, in a de-aerated aqueous solution conta ining 0.05 M Fe3+, 0.05 M Fe2+, 1 M MgSO4 and 0.05 M or 0.1 M H2SO4 (f or the stabilization of the ferrous and ferric ions). The kinetic para meters of the redox couple were determined. The interpretation of the results was based on the existence of a potential drop across the pass ive film, in the case of anodic overpotential. It appears that this re dox couple is unsuitable for the study of the passive film on molybden um implanted stainless steel, owing to the dissolution of this element in sulphuric medium.