Characteristics of Localized Corrosion of Steel in Chloride Solutions

Abstract Pitting of steel in chloride solutions was studied in an experimental cell that permitted measurement of the pH and potential at active and passive areas as well as the current flowing between the areas. The potentials could be controlled potentiostatically. When the potentials of the active and passive areas were held at the same value, the corrosion rate at the active area was decreased by a factor of about 10, compared with the freely corroding rate. The kinetics of the processes in the active area were found to change rapidly with small variations of potential.

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Effect of pH on the Grain Size Dependence of Magnesium Corrosion

CORROSION ◽

10.5006/i0010-9312-68-6-507 ◽

2012 ◽

Vol 68 (6) ◽

pp. 507-517 ◽

Cited By ~ 50

Author(s):

K. D. Ralston ◽

G. Williams ◽

N. Birbilis

Keyword(s):

Grain Size ◽

Corrosion Rate ◽

Anodic Polarization ◽

Localized Corrosion ◽

Anodic Reaction ◽

Left Behind ◽

Kinetics Of ◽

Electrode Technique

Prior works show that grain size can play a role in the corrosion of a metal; however, such works are nominally executed in a single electrolyte/environment at a single pH. In this work, the anodic and cathodic reaction kinetics of pure Mg specimens with grain sizes ranging from approximately 8 μm to 590 μm were compared as a function of pH in 0.1 mol dm−3 sodium chloride (NaCl) electrolytes using anodic polarization experiments and an in situ scanning vibrating electrode technique (SVET). Anodic polarization experiments showed that grain size is important in determining overall electrochemical response, but the environment dictates the form of the grain size vs. corrosion rate relationship (i.e., pH is the overall controlling factor). Consequently, the role of grain size upon corrosion cannot be fully assessed unless a variation in environment is simultaneously studied. For example, the anodic reaction, which dictates active corrosion, also dictates passivation, so the corrosion rate vs. grain size relationship has been shown to “flip” depending on pH. Further, SVET analysis of unpolarized Mg immersed in 0.1 mol dm−3 NaCl electrolyte at neutral pH showed that breakdown of passivity of cast Mg occurred after ~1 h immersion, giving filiform-like corrosion tracks. The front edges of these corrosion features were revealed as intense local anodes, while the remainder of the dark-corroded Mg surface, left behind as the anodes traversed the surface, became cathodically activated. In contrast, grain-refined Mg samples were significantly less susceptible to localized corrosion, and breakdown was not observed for immersion periods of up to 24 h.

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Analysis of the corrosion behavior of steel reinforcement protected by phosphate coatings

MATEC Web of Conferences ◽

10.1051/matecconf/202032902001 ◽

2020 ◽

Vol 329 ◽

pp. 02001

Author(s):

Viktoriya Konovalova

Keyword(s):

Corrosion Rate ◽

Corrosion Behavior ◽

Electrochemical Corrosion ◽

Chloride Ions ◽

Steel Reinforcement ◽

Protective Properties ◽

Phosphate Coatings ◽

Additional Protection ◽

Corrosion Of Steel ◽

Kinetics Of

The influence of phosphate coatings on the corrosion behavior of steel reinforcement in a chloride-containing environment was studied to determine the need for additional protection against corrosion. The main indicators of the corrosion rate of steel reinforcement with phosphate coatings in chloride-containing solutions were determined, confirming the high protective properties of these coatings. It was found that the corrosion rate of steel reinforcement protected by phosphate coatings is reduced by 3 times. The processes of electrochemical corrosion of steel reinforcement of strength class A500S from steel grade St3ps in concrete under the influence of aggressive environments containing chloride ions (2 % MgCl2 solution and HCl solution with pH = 5) were studied. The kinetics of the corrosion process of steel reinforcement with and without protective phosphate coatings in solutions of various compositions has been studied. The change in mass of steel reinforcement protected by phosphate coatings is 3-4 times less than that of samples without coating. The surface potential of steel reinforcement with phosphate films changes significantly more slowly than that of unprotected samples.

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Electrochemical tomography as a nondestructive technique to study localized corrosion of metals

npj Materials Degradation ◽

10.1038/s41529-021-00209-x ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

M. C. van Ede ◽

C. J. Earls ◽

A. Fichtner ◽

U. Angst

Keyword(s):

Corrosion Rate ◽

Electrochemical Techniques ◽

Electrical Potential ◽

Localized Corrosion ◽

Nondestructive Technique ◽

Instantaneous Rate ◽

Electrical Potential Field ◽

Current Densities ◽

Corrosion Of Steel

AbstractWe present an approach, termed electrochemical tomography (ECT), for the in-situ study of corrosion phenomena in general, and for the quantification of the instantaneous rate of localized corrosion in particular. Traditional electrochemical techniques have limited accuracy in determining the corrosion rate when applied to localized corrosion, especially for metals embedded in opaque, porous media. One major limitation is the generally unknown anodic surface area. ECT overcomes these limitations by combining a numerical forward model, describing the electrical potential field in the porous medium, with electrochemical measurements taken at the surface, and using a stochastic inverse method to determine the corrosion rate, and the location and size of the anodic site. Additionally, ECT yields insight into parameters such as the exchange current densities, and it enables the quantification of the uncertainty of the obtained solution. We illustrate the application of ECT for the example of localized corrosion of steel in concrete.

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Macrocell Corrosion of Steel in Concrete under Carbonation, Internal Chloride Admixing and Accelerated Chloride Penetration Conditions

Materials ◽

10.3390/ma14247691 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7691

Author(s):

Zhilu Jiang ◽

Siyao Li ◽

Chuanqing Fu ◽

Zheng Dong ◽

Xuefeng Zhang ◽

...

Keyword(s):

Corrosion Rate ◽

Steel Corrosion ◽

Chloride Penetration ◽

Localized Corrosion ◽

Geometrical Parameters ◽

Correction Coefficient ◽

Two Dimensional ◽

Steel Bar ◽

Corrosion Of Steel ◽

Macrocell Corrosion

Steel corrosion has become the main reason for the deterioration of reinforced concrete structures. Due to the heterogeneity of concrete and the spatial variation of environmental conditions, macrocell corrosion is often formed by localized corrosion, which is more detrimental if the anode is supported by large numbers of cathodes. The macrocell corrosion caused by concrete carbonation has been seldom studied. Furthermore, the influence of geometrical conditions on cathode-controlled corrosion in the chloride environment needs to be further clarified. In this work, the macrocell corrosion of steel embedded in concrete specimens exposed to accelerated carbonation, chloride contamination, and chloride penetration is studied using a modified ASTM G109 method. Concrete specimens with various binder types, geometrical parameters (i.e., concrete cover thickness and the diameter of embedded steel), and boundary conditions were tested. A simplified mathematical model for the prediction of the steel corrosion rate was developed considering two-dimensional oxygen diffusion. The results showed that, at the same level of anodic potential drops, the corrosion current rate in chloride-induced corrosion is higher than that of carbonation-induced corrosion. Chloride contamination is less detrimental to concrete incorporated with slag and pulverized fly ash than it is to pure ordinary Portland cement (OPC), likely due to enhanced chloride binding capacity. The results also indicated that the model considering two-dimensional diffusion can accurately predict the cathodic reaction process on corroded steel bars, which provides a theoretical basis for considering the correction coefficient of steel bar position in the establishment of a steel bar corrosion rate model.

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Inhibition of Aluminum Alloy 2024 Corrosion by Vanadates: An In Situ Atomic Force Microscopy Scratching Investigation

CORROSION ◽

10.5006/1.3278417 ◽

2007 ◽

Vol 63 (7) ◽

pp. 672-688 ◽

Cited By ~ 28

Author(s):

M. Iannuzzi ◽

G. S. Frankel

Keyword(s):

Atomic Force Microscopy ◽

Aluminum Alloy ◽

Open Circuit ◽

Localized Corrosion ◽

Chloride Solutions ◽

Force Microscopy ◽

Atomic Force ◽

Aluminum Alloy 2024 ◽

Kinetics Of

Abstract The morphology and kinetics of the localized corrosion of aluminum alloy (AA)2024-T3 (UNS A92024) at the open-circuit potential were investigated by in situ atomic force microscopy (AFM) scratching. The addition of metavanadate to chloride solutions resulted in outstanding corrosion inhibition. Samples exposed to 0.1 M sodium chloride (NaCl) with no inhibitor developed a trench-like attack at the periphery of large Al-Cu-Fe-Mn-(Si) intermetallic phases. The addition of dilute metavanadate markedly reduced the kinetics of the attack. In addition, most S-phase particles remained free of attack. Higher concentrations of metavanadate increased protection even further so that only high AFM tip forces could induce pitting corrosion. Corrosion attack was immediately observed when AA2024-T3 samples were exposed to chloride solutions containing orange decavanadates. The attack nucleated on the exposed surface but not under the AFM tip. The attack grew continuously, accompanied by gas evolution and formation of corrosion products. Optical inspection after the test indicated severe corrosion damage, confirming an overall poor performance of orange decavanadate solutions as corrosion inhibitors.

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Corrosion of Steel Rebars in Anoxic Environments. Part I: Electrochemical Measurements

Materials ◽

10.3390/ma14102491 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2491

Author(s):

Elena Garcia ◽

Julio Torres ◽

Nuria Rebolledo ◽

Raul Arrabal ◽

Javier Sanchez

Keyword(s):

Corrosion Rate ◽

Electrochemical Impedance ◽

Electrochemical Techniques ◽

Chloride Content ◽

Offshore Platforms ◽

Anoxic Conditions ◽

Current Limit ◽

Anoxic Environments ◽

Corrosion Of Steel ◽

Steel Rebars

The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.

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Test and Study on Impact of Corrosion on Bond Force between Steel and Concrete

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.36.176 ◽

2010 ◽

Vol 36 ◽

pp. 176-181

Author(s):

Xian Feng He ◽

Shou Gang Zhao ◽

Yuan Bao Leng

Keyword(s):

Reinforced Concrete ◽

Corrosion Rate ◽

Concrete Structure ◽

Steel Corrosion ◽

Reinforced Concrete Structure ◽

Bond Force ◽

Steel Bars ◽

Protection Layer ◽

Corrosion Of Steel ◽

The Impact

The corrosion of steel will have a bad impact on the safety of reinforced concrete structure. In severe cases, it may even be disastrous. In order to understand the impact of steel corrosion on the structure, tests are carried out to study corrosion and expansion rules of steel bars as well as the impact rules of corrosion on bond force between steel and concrete. The results show that wet and salty environment will result in steel corrosion; relatively minor corrosion will not cause expansion cracks of protection layers; when steel rust to a certain extent, it will cause cracks along the protection layer; when there exists minor corrosion in steel and the protection layer does not have expansion cracks, the bond force is still large and rapidly decreases as the corrosion rate increases.

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Kinetics of reaction between plutonium(III) and chlorine in chloride solutions

Journal of Inorganic and Nuclear Chemistry ◽

10.1016/0022-1902(62)80016-5 ◽

1962 ◽

Vol 24 (12) ◽

pp. 1617-1621 ◽

Cited By ~ 1

Author(s):

A.S. Ghosh Mazumdar ◽

K.P.R. Pisharody ◽

R.N. Singh

Keyword(s):

Chloride Solutions ◽

Kinetics Of Reaction ◽

Kinetics Of

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The Calculation of the Thickness for Uniform Corrosion and Localized Corrosion in Steel Corrosion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.514 ◽

2011 ◽

Vol 255-260 ◽

pp. 514-518

Author(s):

Zheng Yi Kong ◽

Shan Hua Xu ◽

Yu Sheng Chen

Keyword(s):

Corrosion Rate ◽

Constant Temperature ◽

Safety Assessment ◽

Steel Corrosion ◽

Localized Corrosion ◽

Power Relationship ◽

Uniform Corrosion ◽

Experiment Data ◽

Temperature And Humidity ◽

Corrosion Pits

Because of the complexity of corrosion, the law of uniform corrosion and localized corrosion is still not clear,so it is difficult to assess their impact on the structure safety. In order to differ them and find their own law, we obtain a lot of corrosion specimens by ways of constant temperature and humidity, and then detect the size of corrosion pits by roughness tester. After that, the method for calculating the thickness of uniform corrosion and localized corrosion is proposed. Then the method is used to analyze the experiment data. The result indicates the thickness of uniform corrosion and localized corrosion all increase with the rate of corrosion, and they all show a power relationship with corrosion rate, so it will provide a basis for distinguishing them in safety assessment.

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