Homogeneity and Activity Characterization of Iron Sulfide Films After Immersion in Different Electrolytic Media

Scanning photoelectrochemical microscopy (SPECM) in ferricyanide solution was used to characterize homogeneity and electrochemical activity on nonstoichiometric iron sulfide films (Fe x S y ) after 18 h of immersion in different media (sulphide, nitrate, sulfate, and borate). These films were prepared applying cyclic potential pulses to the carbon steel/sour medium interface [1 M (NH 4 ) 2 S, 500 ppm CN -1 for 15 min. Analysis of the electrochemical behavior and surface morphology was made using electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). In addition, SPECM was used for characterizing electronic conductivity of these films. For a Fe x S y film immersed in a sulfide-rich medium, neither EIS spectra nor SEM images show any important electrical and morphological modifications as compared to a film before immersion. However, SPECM images reveal significant heterogeneity of this Fe x S y film, suggesting surface chemical modifications. The experimental results attained by SEM regarding surface morphology after immersion in nitrate, sulfate, and borate media show good agreement with the current maps achieved by SPECM.

[1]  I. González,et al.  Stability study of iron sulfide films, electrochemically grown on carbon steel, in different electrolytic media , 2002 .

[2]  M. Rincón,et al.  Evolution of non-stoichiometric iron sulfide film formed by electrochemical oxidation of carbon steel in alkaline sour environment , 2002 .

[3]  I. González,et al.  Electrochemical behavior of carbon steel in alkaline sour environments measured by electrochemical impedance spectroscopy , 2000 .

[4]  Stevenson,et al.  Imaging size-selective permeation through micropatterned thin films using scanning electrochemical microscopy , 2000, Analytical chemistry.

[5]  M. Bojinov,et al.  Transpassivity mechanism of iron–chromium–molybdenum alloys studied by AC impedance, DC resistance and RRDE measurements , 1999 .

[6]  M. Orazem,et al.  Modeling of the cast iron/drinking water system by electrochemical impedance spectroscopy , 1999 .

[7]  W. Smyrl,et al.  In Situ High‐Resolution Photoelectrochemical Imaging of Precursor Sites for Pitting in Polycrystalline Titanium , 1999 .

[8]  B. Tribollet,et al.  Impedance spectroscopic study of a steel electrode in condition of scaling and corrosion: Interphase model , 1999 .

[9]  William H. Smyrl,et al.  Simultaneous Scanning Electrochemical and Photoelectrochemical Microscopy by Use of a Metallized Optical Fiber , 1996 .

[10]  I. González,et al.  Diffusion coefficients and electrode kinetic parameters of different Fe(III)-sulfate complexes , 1996 .

[11]  G. Thompson,et al.  An STM Study of the Passive Film Formed on Iron in Borate Buffer Solution , 1995 .

[12]  A. Davenport,et al.  High resolution in situ XANES investigation of the nature of the passive film on iron in a pH 8.4 borate buffer , 1995 .

[13]  William H. Smyrl,et al.  A Novel Approach to Combine Scanning Electrochemical Microscopy and Scanning Photoelectrochemical Microscopy , 1995 .

[14]  William H. Smyrl,et al.  Scanning Electrochemical Microscopy of Precursor Sites for Pitting Corrosion on Titanium , 1993 .

[15]  H. White,et al.  Iontophoretic transport through porous membranes using scanning electrochemical microscopy: application to in vitro studies of ion fluxes through skin. , 1993, Analytical chemistry.

[16]  S. Chander,et al.  A Study of Pyrite/Solution Interface by Impedance Spectroscopy , 1990 .

[17]  J. Bardwell,et al.  Passivation of Iron in Sulfate, Perchlorate, and Borate Solutions: Role of Borate in the Passivation Process , 1988 .

[18]  K. Jüttner,et al.  Electrochemical Impedance Spectroscopy on 3‐D Inhomogeneous Surfaces Corrosion in Neutral Aerated Solutions , 1988 .

[19]  J. Dawson,et al.  Electrochemical Studies of the Passive Film on 316 Stainless Steel in Chloride Media , 1985 .

[20]  B. Tribollet,et al.  Corrosion Study of a Carbon Steel in Neutral Chloride Solutions by Impedance Techniques , 1983 .

[21]  Morris Cohen,et al.  The Anodic Oxidation of Iron in a Neutral Solution I . The Nature and Composition of the Passive Film , 1962 .