Mechanism of transpassive dissolution of nickel-based alloys studied by impedance spectroscopy and rotating ring-disc voltammetry

Betova, Iva; Bojinov, Martin; Kinnunen, Petri; Laitinen, Timo; Pohjanne, Pekka; Saario, Timo

doi:10.1016/s0013-4686(02)00080-4

Cited by 26 publications

(37 citation statements)

References 21 publications

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“…The impedance spectra of the studied alloys in te transpassive region are shown in Figs 5-6. They are to a certain extent analogous to those measured previously during transpassive dissolution of Ni, Ni-Cr and Ni-Cr-Fe alloys in room-temperature electrolytes (8,10). For the Fe-14%Cr steel in the second Tafel-like region (1.2-1.4 V), the impedance spectra pass either through the second, third and fourth quadrants of the complex plane, or through the first and fourth quadrants.…”

Section: Methodssupporting

confidence: 83%

EIS Investigations of Transpassive Dissolution of Ferritic Steels in Aqueous and Molten Electrolytes

2007

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The present paper compares the kinetics of transpassive dissolution of industrial ferritic steels in a phosphoric acid-based electropolishing solution to that for the same materials in molten KH 2 PO 4 . Both steady state and transient techniques point to two parallel pathways of the overall process, the first corresponding to oxidative dissolution of Cr as Cr(VI). The first and the second path is identified as the isovalent dissolution of Fe as Fe(III) mediated by a surface chemical step involving interaction with an electrolyte-originating species. Kinetic models of the process involving only surface reaction steps have been found to reproduce successfully the steady-state and the small amplitude ac response of the studied materials in both electrolytes. The kinetic parameters are estimated by a calculation procedure that involves simultaneous fitting of the impedance spectra at several polarisation potentials and the steady state current vs. potential curve for a particular material-electrolyte combination to the model equations. The ability of the kinetic models proposed for aqueous solutions to account for the behavior of materials in molten salt medium is discussed.

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Section: Methodssupporting

confidence: 83%

EIS Investigations of Transpassive Dissolution of Ferritic Steels in Aqueous and Molten Electrolytes

2007

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“…Nickel-Based Alloys. For Ni−Cr alloys, film growth is considered to be a slow process in parallel to transpassive dissolution and is accordingly neglected. , Further, the transpassive dissolution of Cr is supposed to proceed via the reaction path k 7 − k 8 , that is, some concentration of is assumed to be maintained in the outermost cation layer . Cr(VI) has been detected in the passive films formed on Ni−20%Cr at high potentials in sulfuric acid solution .…”

Section: Reaction Modelmentioning

confidence: 99%

The Influence of Solution Anion on the Mechanism of Transpassive Dissolution of Ferrous- and Nickel-Based Alloys

Bojinov

Tzvetkoff

2003

J. Phys. Chem. B

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The aim of this work is to generalize the model for the transpassive dissolution of ferrous-and nickel-based alloys in acidic solutions by assessing the effect of the solution anion on the individual steps of the process. First, experimental voltammetric and impedance spectroscopic data on transpassive dissolution of pure Cr, Fe-12%Cr, Fe-12%Cr-5%Mo, Fe-25%Cr, Fe-25%Cr-10%Mo, pure Ni, Ni-10%Cr, and Ni-20%Cr in phosphoric acid solution are compared with earlier data for the same materials in sulfuric acid solution. It is found that phosphate affects mainly the dissolution reaction of the main element (Fe and Ni) significantly enhancing the rate of secondary passivation in comparison to sulfate. In addition, the accelerating effect of Mo on transpassive dissolution of Cr is much less pronounced in phosphate solutions. Second, the physicochemical basis of the generalized kinetic model is described. The additional assumptions and simplifications that are necessary to transform the model into a set of kinetic equations are listed, and the individual models for the transpassive dissolution of ferrous-and nickel-based alloys are presented. The kinetic parameters of the transpassive dissolution process in 1 M H 3 PO 4 are determined and compared to those in 1 M H 2 SO 4 published earlier. Finally, some conclusions on the effect of solution anion on transpassive dissolution are drawn, and the limitations of the models are outlined.

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“…Este elemento mejora las propiedades de los aceros inoxidables austeníticos en muchos aspectos: mejora su respuesta mecánica, reduce la rotura de la pasividad, especialmente en medios ricos en cloruro, e incrementa la resistencia a la corrosión por picadura y por grietas o fisuras en distintos medios [44][45][46][47][48][49][50] . Por otro lado, el molibdeno ayuda al cromo presente en el acero inoxidable a formar la capa pasiva [51] y previene la despasivación dentro de las grietas o fisuras [52] . Incluso, se ha demostrado el comportamiento biocida de compuestos de molibdeno sobre bacterias sulfatorreductoras, utilizándose con éxito para prevenir la producción de sulfuro en aguas procedentes de pozos de petróleo [53] .…”

Section: Resistencia a La Corrosión De Las Diferentes Aleaciones De Aunclassified

Efecto de la biopelícula en la corrosión de aceros inoxidables

et al. 2010

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ResumenEn este trabajo se ha estudiado la influencia de las biopelículas en los procesos de corrosión de diferentes aleaciones de acero inoxidable, situadas durante 4 años en dos puntos de una estación depuradora de aguas residuales. Se caracterizó el microambiente físico-químico en el interior de las biopelículas mediante microelectrodos de O 2 , H 2 S y pH, y se cuantificaron las tasas de corrosión a partir del número, diámetro y profundidad de picadura. Los resultados obtenidos muestran un desarrollo más notable de las biopelículas y un número de picaduras significativamente mayor en el canal de salida de desbastes que en el canal de recirculación de fangos. Con base en las características del agua sobrenadante y en las medidas realizadas con microelectrodos, se sugiere que la biopelícula induce la corrosión a través de tres posibles mecanismos: creación de celdas de aireación diferencial, zonas con diferente pH y zonas con elevada producción de sulfuro capaz de reaccionar con iones metálicos. Palabras claveBiopelículas; Biocorrosión; Acero inoxidable; Microelectrodos; Sulfuro. Effect of biofilm in the corrosion of austenitic stainless steels in wastewater treatment plants AbstractIn this work, the influence of the biofilms in the corrosion process of different alloys of stainless steel was studied in two sampling points in a wastewater treatment plant during 4 years. The physicochemical microenvironment within the biofilms was characterized through O 2 , H 2 S and pH microelectrodes. Corrosion rates were quantified from the number, diameter and depth of pits. The results show a remarkable development of the biofilm and a significantly greater number of pits in the grit removal channel than in the sludge recirculation channel. Based on the characteristics of the water phase and microelectrode measurements, our results suggest that biofilms induced corrosion throughout 3 mechanisms: creation of differential aeration cells, areas with different pH and areas having high sulphide production which may react with metal ions.

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Mechanism of transpassive dissolution of nickel-based alloys studied by impedance spectroscopy and rotating ring-disc voltammetry

Cited by 26 publications

References 21 publications

EIS Investigations of Transpassive Dissolution of Ferritic Steels in Aqueous and Molten Electrolytes

EIS Investigations of Transpassive Dissolution of Ferritic Steels in Aqueous and Molten Electrolytes

The Influence of Solution Anion on the Mechanism of Transpassive Dissolution of Ferrous- and Nickel-Based Alloys

Efecto de la biopelícula en la corrosión de aceros inoxidables

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