Voltammetric studies of the transpassive dissolution of mild steel in carbonate/bicarbonate solutions

Rangel, C. M.; Leitão, R.A.; Fonseca, I.

doi:10.1016/0013-4686(89)87094-x

Cited by 34 publications

(10 citation statements)

References 19 publications

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“…The resulting passive layer Fe(OH) 2 vs FeCO 3 constituent ratio depends on whether HCO 3 À or hydroxide (OH À ) dominantly drives the charge transfer steps on which the growth of the corrosion products depend at higher potentials. [39] This mechanism is independent from O 2 traces in the media as reported by Rangel et al [40] Thus, comparability of present results with those of naturally aerated solutions in investigations such as [40][41][42] is sustained. Charge transfer steps of Fe(OH) 2 formation are thermodynamically viable in the E-pH range of 8.4 and 21 g L À1 NaHCO 3 in Figures 6(a) through (c), and 42 g L À1 NaHCO 3 in Figure 6(a) only: [36] Fe þ H 2 O !…”

Section: E P1 and E P2supporting

confidence: 87%

“…In Figures 6(a) and (b), decreasing i p values in this region with increasing [NaHCO 3 ] indicates the gradually enhancing protectiveness of FeCO 3 at higher anodic potentials, [40,44] plotted vs pH in Figure 8(a). The potential difference (DE) parameter, between the most anodic passive layer development potential (E p1 or E p2 ) and the earliest breakdown potential (E bd1 ), is plotted vs pH in Figure 8(b).…”

Section: E P1 and E P2mentioning

confidence: 90%

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Low Alloy X100 Pipeline Steel Corrosion and Passivation Behavior in Bicarbonate-Based Solutions of pH 6.7 to 8.9 with Groundwater Anions: An Electrochemical Study

Gadala

Alfantazi

2015

Metall Mater Trans A

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This research investigates the fundamental corrosion and passivation processes occurring on API-X100 pipeline steels before, during, and after passive layer formation in bicarbonate-based simulated soil solutions of pH 6.7 to 8.9. Free corrosion potentials decrease exponentially with bicarbonate (and pH), owing to increased water and bicarbonate reduction in more alkaline conditions and the coupled iron oxidation reaction. Active corrosion rates at potentials slightly above open circuit potential increase with bicarbonate, until a concentration of 1.68 g L À1 sodium bicarbonate (plus dilute amounts of chlorides/sulfate) at which first signs of film formation appear. Thereon, increased bicarbonate concentration generally decreases current densities and resists ferrous-oxide product formations due to improved iron carbonate formation conditions precipitating more durable passive layers. Potentiodynamic polarization in the anodic regime reveals varying electrochemical processes involving interactions between hydroxide, carbonate, and oxide complexes with ferrous, with diverse pH and potential dependencies. The products of corrosion reactions were investigated by scanning electron microscopy, X-ray diffraction, and/or X-ray photoelectron spectroscopy.

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Section: E P1 and E P2supporting

confidence: 87%

Section: E P1 and E P2mentioning

confidence: 90%

Low Alloy X100 Pipeline Steel Corrosion and Passivation Behavior in Bicarbonate-Based Solutions of pH 6.7 to 8.9 with Groundwater Anions: An Electrochemical Study

Gadala

Alfantazi

2015

Metall Mater Trans A

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“…Many investigations were carried out using highly alkaline solutions [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] or using buffer solutions as carbonate/bicarbonate [19][20][21][22][23][24][25][26] or borate buffer [27][28][29][30][31][32] when a constant and not very high pH is desirable. Many products have been identified as resulting from the anodic polarization of iron at different potentials, by different surface analysis techniques [6][7][8][9][10][11][12][13]22,26,[33][34][35][36][37][38][39][40]…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Behaviour of Iron in NaOH 0.01 mol/L Solutions Containing Variable Amounts of Silicate

Amaral¹,

Müller²

1999

J. Braz. Chem. Soc.

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Ciclos voltamétricos repetitivos do ferro em soluções de NaOH contendo concentrações variáveis de silicato entre 10 ppm e 1500 ppm, mostram comportamentos diferentes da primeira varredura quando comparada com as subsequentes, em todas as soluções testadas. Esta diferença indica uma modificação do processo de formação do filme com a ciclagem. Foi observada uma transição do perfil i/E entre 10 ppm e 100 ppm de silicato o que permite formular considerações sobre a incorporação de silicato ao filme.Repetitive voltammetric cycling of iron in NaOH solutions containing variable silicate concentrations between 10 ppm and 1500 ppm, shows different behaviour for the first scan when compared to the following ones in all studied solutions. This difference indicates a modification on the film formation process. A transition in the i/E profile between 10 ppm and 100 ppm of silicate was observed allowing considerations about silicate incorporation to be formulated.

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“…Also small changes in pH, particularly in the range of 12-13, can contribute to the appearance of peaks in the transpassive region which have been attributed to the oxidation of Fe(III) to Fe(VI) [19,20].…”

Section: Introductionmentioning

confidence: 98%

“…Several authors [14][15][16][17][18][19][20][21][22][23][24][25][26] have carried out cyclic voltammetric studies on iron and steel passivity in sodium and potassium alkaline media. The number of peaks shown on the recorded voltammograms is quite diverse.…”

Section: Introductionmentioning

confidence: 99%

A voltammetric study on the corrosion of prestressed steel in saturated Ca(OH)2 solution containing chloride ions

et al. 2009

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An electrochemical study of prestressed steel in saturated Ca(OH) 2 aqueous solutions (pH 12) was carried out in the absence and in the presence of chloride ions, in such a concentration that simulates the composition of seawater. Cyclic voltammetry, linear sweep voltammetry, open circuit potential transients, atomic absorption spectroscopy and scanning electron microscopy coupled to electron diffraction spectroscopy were employed. The linear polarisation curves analysis led to the determination of polarisation resistance, R p , corrosion potential, E corr , corrosion current density, j corr , Tafel slopes, breakdown potential, E b and repassivation potential E repass . A linear dependence of the breakdown potential, E b , on the square root of scan rate was obtained, according to the Point Defect Model (PDM). A crossover characteristic of the nucleation processes was observed in the presence of chloride ions. SEM/EDS studies revealed, as expected, a strong influence of the presence of chloride ions observed in the transpassive and the active regions. In conclusion, chloride ions contribute to enhance the corrosion of steel, most probably due to their adsorption on both the active and the passive electrode surfaces.

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Voltammetric studies of the transpassive dissolution of mild steel in carbonate/bicarbonate solutions

Cited by 34 publications

References 19 publications

Low Alloy X100 Pipeline Steel Corrosion and Passivation Behavior in Bicarbonate-Based Solutions of pH 6.7 to 8.9 with Groundwater Anions: An Electrochemical Study

Low Alloy X100 Pipeline Steel Corrosion and Passivation Behavior in Bicarbonate-Based Solutions of pH 6.7 to 8.9 with Groundwater Anions: An Electrochemical Study

Electrochemical Behaviour of Iron in NaOH 0.01 mol/L Solutions Containing Variable Amounts of Silicate

A voltammetric study on the corrosion of prestressed steel in saturated Ca(OH)2 solution containing chloride ions

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