The mechanism of pitting of high purity iron in NaCl solutions

Alvarez, M.G.; Galvele, J.R.

doi:10.1016/0010-938x(84)90133-1

Cited by 119 publications

(57 citation statements)

References 30 publications

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“…These values of the Tafel coefficient calculated by relations (17) and (20) are close to the experimental data (Table 1), which allows us to assert that dissolution of the metal proceeds according to reactions (14) and (15) or (14) and (18). It is worth noting that these reactions are not the only possible ones.…”

Section: F(zl + Otzl )supporting

confidence: 56%

“…Due to the complexity of the systems under study, other mechanisms of the process are also possible. In this case, a whole spectrum of various intermediates is expected to appear [4,10,14].…”

Section: F(zl + Otzl )mentioning

confidence: 99%

“…where k 4 is a constant and z 4 and z 4 are the number of electrons that take part in reactions (14) and (18), respectively.…”

Section: F(zl + Otzl )mentioning

confidence: 99%

“…Estimation of the obtained experimental data according to the classical electrochemical equations of the kinetics of electrode processes [4,11 ] shows that the first stage of electrochemical dissolution of the metal in stress concentrators must be two-electron and can be realized according to the scheme [10] Fe+OH-~ FeOH +e, FeOH + Fe ---) Fe2OH § + e. I (14) Subsequent stages proceed in the following two most probable ways: If the reaction…”

Section: F(zl + Otzl )mentioning

confidence: 99%

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Stagewise behavior of the electrochemical dissolution of a loaded metal under the conditions of its local interaction with corrosive media

Dmytrakh¹,

Panasyuk²,

Ézers'ka³

1998

Mater Sci

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We show that the process of local electrochemical dissolution of iron of loaded low-carbon 20 steel (c0. 2 = 270 MPa) in a corrosive medium (3% aqueous NaCI solution, pH 6.9) is multistage. The characteristics of the process depend on the form of the surface interacting with the corrosive medium. The investigated cases are arranged in the following order according to the rate of dissolution of the metal: a smooth surface, a stress concentrator, and a stress concentrator with a short crack-like defect. We propose and detect the corresponding electrochemical reactions and their sequence (stagewise behavior) realized in the course of the process. The electrochemical parameters of local anodic dissolution of the metal at tips of corrosion cracks of various depths and openings are determined, On the basis of these results, we suggest an autocatalytic mechanism of dissolution of the metal in which Fe 2+ ions are autocatalytic particles. We demonstrate agreement between the results calculated by using classical electrochemical equations for the kinetics of electrode processes and experimental data obtained in corrosive media with various concentrations of Fe 2+ ions in the range Cre2~ = 1.0.10~s-2.0 9 10 -1 mole/liter. This means that the indicated mechanism can be realized at the tip of a corrosion crack.The nature of corrosion fracture of structural metals depends on many factors, whose investigation requires the performance of simultaneous experiments in various fields (fracture mechanics, materials science, and the physics and chemistry of materials). Numerous researchers call special attention [1][2][3], in particular, to the dominant role of electrochemical processes in the early stages of corrosion fracture of a metal as compared to mechanical factors. In certain cases, these processes can govern the mechanism and rate of formation of corrosion defects on the surface, which is important for evaluation of the serviceability of structural materials under the action of corrosive media.Up to now, one studied mainly electrochemical dissolution of a smooth unloaded surface of the metal [4] in the case where the rate of dissolution is determined only by diffusion processes in the medium and the electric double layer on the surface is homogeneous. However, in practice, electrochemical processes of dissolution of metal from the surfaces of complicated geometry (technological and structural stress concentrators, cracks, mechanical defects, etc.) are more widespread. It is known [1] that the complicated form of the surface results in the inhomogeneity of the structure of the electric double layer and, hence, heterogeneity of its energy state. This leads to the appearance of localized centers with increased energy on the surface, which significantly decrease the energy barrier of electrochemical dissolution of the metal. As a result, significant acceleration of the process can be observed, which is not typical of a smooth open surface. Here, the type and sequence (stagewise behavior) of the electrochemical reactions that des...

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Section: F(zl + Otzl )supporting

confidence: 56%

Section: F(zl + Otzl )mentioning

confidence: 99%

“…where k 4 is a constant and z 4 and z 4 are the number of electrons that take part in reactions (14) and (18), respectively.…”

Section: F(zl + Otzl )mentioning

confidence: 99%

Section: F(zl + Otzl )mentioning

confidence: 99%

See 2 more Smart Citations

Stagewise behavior of the electrochemical dissolution of a loaded metal under the conditions of its local interaction with corrosive media

Dmytrakh¹,

Panasyuk²,

Ézers'ka³

1998

Mater Sci

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“…Reinforced concrete structures are seriously affected by steel corrosion due to exposure to chlorides from seawater, salt and saltwater, deicing chemicals, brackish water or spray from these sources. The reduction in the structural performance of reinforced concrete members due to corroded steel is caused by the loss in the effective cross-sectional area of concrete due to cracking in the cover concrete, loss in the mechanical properties and performance of the reinforcing bars due to reduction of their cross-sectional area and also loss of bonding [10,[14][15][16][17]. Seismic loads are known to act on the load bearing elements of structures in the form of high strain reversals, which can be simulated as single axis LCF.…”

Section: Introductionmentioning

confidence: 99%

Corrosion of reinforcing steel and low cycle fatigue behaviour

Apostolopoulos

Michalopoulos²

2007

Materials & Corrosion

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Chloride induced corrosion of reinforcing steel can be highly detrimental and of great influence on the low cycle fatigue (LCF) characteristics. An experimental study conducted on BSt500 s reinforcing steel, showed that the LCF and life expectancy were reduced considerably according to the level of corrosion. Low cycle strain controlled fatigue testing under AE 1 and AE 2.5% constant amplitude strain indicated that the corroded steel bars exhibit gradual reduction in available energy, number of cycles to failure and the load bearing ability. Formation of irregularities such as pits, notches and cavities occurred on the corroded steel surface and stress concentration points were developed which are highly localized at imperfections and especially at the rib bases. The experimental investigation of the corroded specimens subjected to LCF showed that the life expectancy, the remaining energy density and the strength properties were reduced considerably as a result of these irregularities combined with the mass loss and reduction of the exterior hard layer of martensite. Structural design capable of resisting seismic activity that does not account for the reduction of the load bearing ability and life expectancy as well as the cumulative plastic deformation of the steel reinforcement due to corrosion and loading history that a structure will be subjected in harsh climatic environments and ground oscillating motion could lead to serious and unpredictable performance.

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