Electrochemical and Surface Study of the Oxide Growth and Conversion on 316L Stainless Steel

Abstract

Oxide formation and conversion mechanism as a function of potential on 316L stainless steel was investigated using electrochemical and surface analysis techniques. All of the results were consistent with the electrochemical thermodynamics. Four potential regions were identified for anodic oxidation. In Ox I, conversion of the defective chromium oxide layer to an iron/chromium spinel phase occurred. This was followed by conversion of the upper Fe₃O₄ oxide to a passivating γ-Fe₂O₃ layer in Ox II. At potentials > 0.0 V_SCE, Ox III and IV involved the formation of γ-FeOOH and conversion of Cr^III to soluble Cr^VI respectively contributing to film breakdown.