The inhibition of pit nucleation and growth on the passive surface of iron in a borate buffer solution containing Cl− by oxidizing inhibitors

Fujioka, E.; Nishihara, Hiroshi; Aramaki, Kunitsugu

doi:10.1016/s0010-938x(96)00075-3

Cited by 68 publications

(28 citation statements)

References 23 publications

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“…This may result in lowering of the crystallinity of the upper layer. The structure of the passivation film proposed in this study was in good agreement with the models by Sastri et al [6] and Fujioka et al [7] The differences in the crystallinity of the film and the existence of W 6+ with and without tungstate was clearly shown in this study. It is supposed that corrosion resistance is improved in the early stage by (1) suppression of diffusion of corrosion factors such as Cl − by the low crystalline layer, (2) the barrier effect of W 6+ in the film, which inhibits the corrosion reaction.…”

Section: Discussionsupporting

confidence: 91%

“…Tungstate is known as an inhibitor which forms a passivation film that suppresses the anodic process of iron corrosion, resulting in suppression of the nucleation and propagation of corrosion pits [7]. According to the potential-pH phase diagram for a Fe-W binary system [8] and WO 3 , is formed by neutralization of the solution near the interface between the solution and the surface, and as a result, the concentration of W in the upper layer increases.…”

Section: Discussionmentioning

confidence: 99%

“…Tungstate, which is one oxoacids, inhibits anodic reaction by forming an ultrathin passivation film containing W on a steel surface in an acidic or a neutral solution [6,7]. Although the elemental depth distributions and chemical states of the film have been revealed by surface analytical techniques, the morphology and crystallinity of the film have not been adequately investigated.…”

Section: Introductionmentioning

confidence: 99%

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An Ultrathin Corrosion-Resistant Film on a Steel Surface Formed by Dipping in a Tungstate Solution

Aoyama¹,

Nagoshi²,

Tachibana³

et al. 2016

e-J. Surf. Sci. Nanotech.

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The surfaces of steel specimens after dipping in a solution with or without tungstate addition, followed by a corrosion test, were investigated by various techniques, e.g., cross-sectional Cs-(S)TEM, SEM and XPS, to gain an improved understanding of the role of tungstate in corrosion resistance. The corrosion reaction during the test was drastically suppressed when tungstate was added. A crystalline film approximately 4 nm thick consisting of Fe and O was formed on the surface after dipping in the solution without tungstate. After dipping in the solution with tungstate, a film consisting of Fe, O and W was formed with the thickness of about 4 nm. The latter film consisted of two layers; the outer layer showed lower crystallinity and a higher W concentration. This film improved corrosion resistance. It is supposed that (1) barrier properties are improved by the low crystalline layer or (2) W 6+ in the film inhibits the corrosion reaction. The WO 2− 4in the solution also protected the surface during the test. When the ultrathin film is destroyed, WO 2− 4reacts with iron ions eluted from corrosion pits to form thicker protective films and pit propagation is also suppressed by segregation of W 6+ in the corrosion products above pits.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Ultrathin Corrosion-Resistant Film on a Steel Surface Formed by Dipping in a Tungstate Solution

Aoyama¹,

Nagoshi²,

Tachibana³

et al. 2016

e-J. Surf. Sci. Nanotech.

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“…However, the number of applications in which these alloys are utilized is limited due to their relatively poor corrosion resistance, especially in saltwater environments 4), 5) . Moreover, in alkaline or neutral environments, pitting corrosion occurs when the concentration of chloride ions exceeds a critical value Cl pit 6), 7) . Lafront et al 8) studied the pitting corrosion of AZ91D (die cast and thixocast) and AJ62x (die cast) Mg alloys immersed in an alkaline chloride medium (0.1 M NaOH 0.05 M NaCl 2 ml H 2 O 2 ) with a pH value of 12.3, and they derived results for the passivation zone, the pitting current, and the average corrosion rate using electrochemical noise (EN) techniques.…”

mentioning

confidence: 99%

Corrosion Behavior of AZ31 Magnesium Alloy in Dilute Sodium Chloride Solutions

Wang

Shinohara

Zhang

2009

ZAKAEP

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Magnesium (Mg) and its alloys are widely used as structural materials in many fields because of their considerable physical strength and mechanical properties such as low density and high strength-to-weight ratio. These alloys are extremely popular in the automotive industry as they reduce the total weight of a vehicle, leading to saving of fuel and a reduction in pollution 1) 3) . However, the number of applications in which these alloys are utilized is limited due to their relatively poor corrosion resistance, especially in saltwater environments 4), 5) . Moreover, in alkaline or neutral environments, pitting corrosion occurs when the concentration of chloride ions exceeds a critical value Cl pit 6), 7). Lafront et al. 8) studied the pitting corrosion of AZ91D (die cast and thixocast) and AJ62x (die cast) Mg alloys immersed in an alkaline chloride medium (0.1 M NaOH 0.05 M NaCl 2 ml H 2 O 2 ) with a pH value of 12.3, and they derived results for the passivation zone, the pitting current, and the average corrosion rate using electrochemical noise (EN) techniques. The results of the EN analysis techniques showed that the relative duration of the active and passive periods depended on the casting conditions.Generally, the corrosion resistance of Mg alloys depends on the formation of passive surface films and varies with the medium to which the specimen is exposed 8) . Hara et al. 9) reported that the surface films that form in neutral NaCl and Na 2 SO 4 solutions on open-circuit exposure influence the corrosion and electrochemical behaviors of pure Mg and its alloys. The surface films, which are mainly composed of Mg(OH) 2 , have a protective ability to Mg in the solutions. Due to the existence of a barrier layer in the surface films during immersion, the growth of the surface film is hampered as there is a breakdown in passivity.From the results of an atmospheric exposure test 10) , the test site did not have considerable effect on the corrosion behavior of an AZ31 Mg alloy. The results also implied that the corrosion behavior during rain, when the test coupons are immersed in dilute solutions, is important. Many studies have reported the corrosion behaviors of Mg alloys in concentrated aqueous solutions such as 3.5 wt NaCl solution in literatures 11) 13) . However, the corrosion behavior of the AZ31 Mg alloy on immersion in rainwater containing Cl ions at a site in the seashore area is still unknown. In this study, the corrosion behavior of the AZ31 Mg alloy in dilute NaCl solutions was investigated by electrochemical measurements and X ray diffraction (XRD). -A 10-mm-diameter bar of commercial AZ31 (3 Al 1 Zn) Mg alloy was used in this study. The specimen was prepared by cutting a cylinder with a length of 10 mm from the bar, connecting the cylinder to a lead wire, and then embedding them completely in epoxy resin with the exception of one of the round surfaces of the cylinder, which was left exposed. Prior to the performance of the electrochemical tests, the exposed surface was mechanically polished up to...

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“…Regarding pitting corrosion, nitrates may act either as activating or inhibiting species (Fujioka et al, 1996). This property of nitrates was also realized in the case of Fe.…”

Section: Under Potential-controlled Conditionsmentioning

confidence: 84%

Oscillatory Phenomena as a Probe to Study Pitting Corrosion of Iron in Halide-Containing Sulfuric Acid Solutions

Sazou¹,

Pavlidou²,

Diamantopoulou³

et al. 2012

Pitting Corrosion

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The inhibition of pit nucleation and growth on the passive surface of iron in a borate buffer solution containing Cl− by oxidizing inhibitors

Cited by 68 publications

References 23 publications

An Ultrathin Corrosion-Resistant Film on a Steel Surface Formed by Dipping in a Tungstate Solution

An Ultrathin Corrosion-Resistant Film on a Steel Surface Formed by Dipping in a Tungstate Solution

Corrosion Behavior of AZ31 Magnesium Alloy in Dilute Sodium Chloride Solutions

Oscillatory Phenomena as a Probe to Study Pitting Corrosion of Iron in Halide-Containing Sulfuric Acid Solutions

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