Experimental and Modeling Studies on Mass Transport and Electrochemical Factors Influencing Stainless Steel Pitting and Repassivation

Abstract

Studies on the critical conditions describing pitting stability and repassivation have focused on either determining the dissolution flux and solution chemistry or the potential. Experimental and modeling techniques toward building a quantitative relationship among the critical conditions were performed in this study. The artificial pit (lead-in-pencil) electrode constructed from stainless steel wires of small diameter was used as the tool to obtain measurable estimates of the critical dissolution flux and potential in aqueous sodium chloride (NaCl) solution. Both estimates were obtained using a single experimental technique. Experimental results so obtained were utilized to develop a one-dimensional diffusional model with representative boundary conditions. Results from these analyses indicated that the critical surface concentration required for stable pitting (or to prevent repassivation) may be more dilute than previously accepted in the literature.