Mechanism of Crevice Corrosion

Rosenfeld, I. L.; Маршаков, И. К.

doi:10.5006/0010-9312-20.4.115t

Cited by 114 publications

(47 citation statements)

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“…A fixed crevice height of 0.25 mm was used in this study. This clearance is less than the thickness of the oxygen diffusion layer (5,12) and lies in the range of crevice heights observed by Rosenfeld and Marshakov to give maximum corrosion for iron in the presence of various inorganic inhibitors (13). In a typical experiment, the crevice height was set, both the crevice and external iron electrodes were left uncoupled for 15 min, and then the two parts were short-circuited, using the potentiostat as a zero resistance ammeter.…”

Section: Methodsmentioning

confidence: 91%

A Competitive Adsorption Model for the Inhibition of Crevice Corrosion and Pitting

McCafferty

1990

J. Electrochem. Soc.

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Similarities in the inhibition of crevice corrosion and pitting can be explained on the basis of competitive adsorption between inhibitive and aggressive ions. A mathematical model has been developed which takes into account competitive adsorption between aggressive ions (C1) and inhibitive ions (CrO4=), with each ion adsorbing according to a Temkin isotherm. In the case of crevice corrosion of iron, this model explains the linear relationship which has been observed between the logarithm of the chloride ion activity and the logarithm of the minimum chromate activity required for protection against crevice corrosion. In the case of pitting, this same model describes the linear decrease in pitting potential with the logarithm of the C1-activity at constant CrO4 = concentration. The mathematical model, in conjunction with electrochemical data and adsorption isotherms, allows calculation of a critical ratio, Ocrit, of surface coverages of aggressive to inhibitive ion necessary to initiate localized corrosion. This critical ratio was computed to be approximately the same value (1.9) for the crevice corrosion and pitting of iron in chromate/chloride solutions. Nominal confirmation for this computed value of Ocrit was provided by surface analyses using XPS.It is well established (1) that the various forms of localized corrosion share certain common features due to the limited exchange of local and bulk electrolytes. In crevice corrosion and stress corrosion cracking, for instance, the long narrow diffusion path limits access to the bulk electrolyte. In pitting corrosion, a porous cap of corrosion products can be the barrier. Based on these commonalities of restrictive geometry and resulting local acidity, Brown developed the concept that the various types of localized corrosion are different geometric manifestations of the same general phenomenon of "occluded cell corrosion" (2).The work of Br'own focused on similarities in the various forms of localized corrosion well into their propagation stages. There have been reports in the literature which suggest that crevice corrosion and pitting are also similar prior to the propagation stage. For instance, SzklarskaSmialowska and Mankowski (3) found that pits formed within crevices on stainless steel and suggested that "crevice corrosion can be considered as a particular case of pitting." Rosenfeld (4) suggested the converse, i.e., that "pitting corrosion on stainless steel should be regarded as a special kind of crevice corrosion .... "The present work shows that the inhibition of both crevice corrosion and pitting can be described by a competitive adsorption model in which aggressive ions (C1-) and inhibitive ions (CrO4 =) compete for sites on the metal surface. If the ratio of the surface coverages of aggressive to inhibitive ions exceeds a certain critical value, Oc~it, then breakdown of passivity occurs as crevice corrosion on shielded surfaces or as pitting on open surfaces. Corrosion experiments combined with adsorption isotherms show that Ocrit ~-1.9 and is the same ...

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Section: Methodsmentioning

confidence: 91%

A Competitive Adsorption Model for the Inhibition of Crevice Corrosion and Pitting

McCafferty

1990

J. Electrochem. Soc.

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“…2 [15,25]. This is because Cl − ions have small diameters allows it to penetrate through the protective oxide film and displace oxygen at the sites where metal-oxygen bond is the weakest [15,26,27].…”

Section: Chronoamperometric Measurementsmentioning

confidence: 99%

Effects of exposure time on the anodic dissolution of Monel-400 in aerated stagnant sodium chloride solutions

Sherif

2011

J Solid State Electrochem

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The anodic dissolution of Monel-400 (63.0% Ni, 28-34% Cu) alloy after its immersion in freely aerated stagnant 3.5% NaCl solutions for 0, 24, and 72 h has been investigated. The study was carried out using a variety of electrochemical techniques and gravimetric measurements after varied exposure periods (5-160 days). The work was complemented by scanning electron microscopy and energy dispersive X-ray analyzer (SEM/EDX) investigations. The electrochemical measurements showed that Monel suffers both general and pitting corrosion. The severity of uniform corrosion decreased, while pitting one increased with increasing the immersion time to 24 h and further to 72 h before measurements. Gravimetric data indicated that the weight loss increased, while the corrosion rate decreased for Monel with time. SEM images and EDX profile analyses confirmed that the corrosion of Monel after 160 days immersion in NaCl solutions occurs due to the selective dissolution of nickel.

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“…ions were concentrated inside the defects as a consequence of reduction reaction. Hence, low pH atmosphere was formed inside the defects, which accelerated the corrosion damage [20,34,35]. At 1 9 10 -2 A/cm 2 , broad sunken surface damage was observed on the coating layer.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Characteristics in Seawater for Cold Thermal Spray-Coated Al–Mg Alloy Layer

Park

Kim

2016

Acta Metall. Sin. (Engl. Lett.)

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For corrosion protection of carbon steel in a marine environment, cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy wires. The surface hardness of Al and Al-Mg thermal spray coatings increased with Mg content. And the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating layers. The Al and Al-Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential measurements. And an anodic polarization experiment revealed a tendency of activation polarization with no passivation. Furthermore, the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area, and the Al-3Mg thermal spray coating layer presented less surface damages than others. In addition, the Al-3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion protection. Therefore, it is an optimal thermal spray material for sacrificial anode.

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Mechanism of Crevice Corrosion

Cited by 114 publications

References 0 publications

A Competitive Adsorption Model for the Inhibition of Crevice Corrosion and Pitting

A Competitive Adsorption Model for the Inhibition of Crevice Corrosion and Pitting

Effects of exposure time on the anodic dissolution of Monel-400 in aerated stagnant sodium chloride solutions

Electrochemical Characteristics in Seawater for Cold Thermal Spray-Coated Al–Mg Alloy Layer

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