Open AccessOn the Critical Factors for Estimating the Pit Stability Product under a Salt Film
Author(s) -
Ke Wang,
Mobin Salasi,
Sam Bakhtiari,
Mariano Iannuzzi
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ac0aab
Subject(s) - electromigration , diffusion , limiting current , dissolution , salt (chemistry) , electrolyte , limiting , thermodynamics , materials science , analytical chemistry (journal) , stability (learning theory) , metal , chemistry , effective diffusion coefficient , metallurgy , composite material , electrochemistry , chromatography , electrode , physics , mechanical engineering , medicine , radiology , magnetic resonance imaging , machine learning , computer science , engineering
The pit stability product of 316L stainless steel (SS) under a salt film was examined by experimental techniques, analytical methods, and numerical modeling. Both analytical and numerical results suggested that electromigration had a measurable contribution to the dissolution current during stable pit growth under a salt film, preventing the use of the 1D Fick’s law of diffusion to obtain the pit stability product under such conditions. Moreover, the numerical results indicated that migration contributed to almost ⅔ of the mass transport limiting current. Although the diffusion coefficient of metal cations decreased with an increasing concentration inside the pit, it could be replaced by a constant diffusion coefficient, defined as an equivalent diffusion coefficient. When the complexation reaction was cconsidered, the modeling results agreed with the experimental data, indicating that a 4.2 M FeCl 2 could be used as a simplified pit-like electrolyte to estimate the pit stability product under a salt film for 316L SS.