A RRDE study of the electrochemical behavior of iron in solutions containing silicate and sulphate at pH 10–13

Amaral, Suzana Trindade; Müller, Ivan

doi:10.1016/s0010-938x(98)00149-8

Cited by 30 publications

(18 citation statements)

References 40 publications

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“…This layer is to some extent different than just a passive (or oxide layer), since the iron oxides/hydroxides are substituted by species from the surrounding medium (as Ca, Si etc.) [9][10][11]. Therefore, the discussion in this work refers to the, considered as more accurate, term ''product layers'', rather than ''oxide layers'' only.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical behavior of corroded and protected construction steel in cement extract

Koleva

2011

Materials & Corrosion

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The corrosion behavior of corroded, cathodically protected and control (reference) construction steel, previously embedded in concrete, was studied in cement extract (pH 12.6, considered as concrete pore water), using cyclic voltammetry (CVA) and potentiodynamic polarization (PDP). The necessity for this investigation occurred from the previously observed and commented discrepancies in the recorded corrosion parameters for corroded and protected steel in embedded conditions [1]. Therefore this study aimed to evaluate how the ''naturally'' formed in concrete product layers (after 460 days) will influence the electrochemical behavior of the steel in cement extract. The PDP measurements reveal the lowest corrosion resistance to be for the previously corroded steel samples, for which the most active corrosion potential (À0.7 V SCE) and the highest anodic current in the potential region 0 to 0.6 V (SCE) were recorded. The CVA tests support the results from PDP and correlate the properties of the naturally formed layers with the recorded peak current densities and peak potentials with cycling. For all specimens, except the corroded ones, the peak potential initially shifts anodically, which denotes for a high corrosion resistance in the former and low corrosion resistance in the latter case. For the control and protected specimens, the passive current in the potential region of 0 to 0.6 V (SCE) remains almost unchanged with cycling, i.e. the protective properties of the initial layers remain unchanged. Thickening of the film with cycling does not influence the corrosion resistance of the previously formed layers. For the protected specimens, however, a tendency to reach a steady state and change of peak currents' height only were observed, without a pronounced shift to more anodic values. An increase in the peak current only, not accompanied by anodic shift of the peak potential, suggests that the layers in the cathodically protected specimens are more homogeneous and compact. Overall it can be stated that in cement extract, the product layer with lowest corrosion resistance is the one on the surface of the corroded steel reinforcement. The product layers in the protected specimens (although similar to control conditions) are with the highest corrosion resistance.

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Section: Introductionmentioning

confidence: 99%

“…[11][12][13]), some discrepancies and unclarity in interpretation of the derived parameters might occur [1,14]. For example, the corrosion current density of a corroding steel surface would be normally expected to be higher than a protected steel surface.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical behavior of corroded and protected construction steel in cement extract

Koleva

2011

Materials & Corrosion

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“…Similar effects are attributed to the presence of Si, which is about 21 w.% in Portland cement in the form of SiO 2 . Adding SiO 2 to model pore solutions with pH ~10-13, is found to promote a more protective film, probably due to its incorporation in the film [4,5].…”

Section: Introductionmentioning

confidence: 98%

Electrochemical Measurements in Cement Extract Solutions on Reinforcing Steel, Previously Conditioned in Concrete

et al. 2007

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The corrosion behavior of reinforcing steel, previously embedded in concrete and maintained in conditions of corrosion and two regimes (conventional and pulse) of cathodic protection (CP), was characterized using electrochemical measurements in cement extract (CE) solutions of pH 12.6. The investigation aimed at determination of the properties of the product layers, previously formed on the steel surface. The study further allowed evaluation of the CP effectiveness in terms of steel surface oxidation/reduction behavior in the alkaline medium of CE. Based on the similar electrochemical behavior of protected specimens, it can be concluded that the pulse CP is as effective as the conventional CP regime. Moreover, the surface film, formed in pulse CP conditions appears to be more homogeneous and resistive, compared to the conventional CP regime.

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“…In presence of various anions, iron dissolution was explained invoking the participation of SCTC and mechanistic schemes. Many studies about active dissolution and passivation were carried in alkaline solution [3][4][5][6][7][8][9][10][11][12] and many electrochemical studies have been investigating the behaviour of iron in aqueous solution. Several mechanisms have been suggested [3][4][5][6][7][8][9] [4,5,14].…”

Section: Introductionmentioning

confidence: 99%

“…Many studies about active dissolution and passivation were carried in alkaline solution [3][4][5][6][7][8][9][10][11][12] and many electrochemical studies have been investigating the behaviour of iron in aqueous solution. Several mechanisms have been suggested [3][4][5][6][7][8][9] [4,5,14]. Under potentiodynamic conditions, the first anodic peak is specifically related to Fe(OH) 2 formation and the second peak to Fe(OH) 2 with three dimensional oxide film, and the third peak to FeOOH formation [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Role of Halides on the Passivation of Iron in Alkaline Buffer Solutions

Begum

Basha

Muralidharan

2010

Port. Electrochim. Acta

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Cyclic voltammetric studies were carried out on pure iron in alkaline borate and phosphate buffer solutions at pH 10.8. At higher potentials, on anodic polarization, iron forms FeB 4 O 7 and FeOOH in borate buffer, and FeHPO 4 in phosphate buffer which got converted to higher valency phosphates. In phosphate solutions, in presence of halides, the interfacial diffusion layer turned to be cation selective outer sublayer and an anion selective inner sublayer, and in borate solutions a precipitate layer of metal oxyhydroxide was formed, which was anion selective, and anions adsorb on this.

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A RRDE study of the electrochemical behavior of iron in solutions containing silicate and sulphate at pH 10–13

Cited by 30 publications

References 40 publications

Electrochemical behavior of corroded and protected construction steel in cement extract

Electrochemical behavior of corroded and protected construction steel in cement extract

Electrochemical Measurements in Cement Extract Solutions on Reinforcing Steel, Previously Conditioned in Concrete

Role of Halides on the Passivation of Iron in Alkaline Buffer Solutions

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