Analysis of the role of electrode capacitance on the initiation of pits for A516 carbon steel by electrochemical noise measurements

Cheng, Y. Frank; Wilmott, M.; Luo, Jing‐Li

doi:10.1016/s0010-938x(98)00181-4

Cited by 62 publications

(27 citation statements)

References 16 publications

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“…This technique was mainly used for materials such as stainless steel, aluminum and its alloys which are known to be easily passivated. [22] In this work, the electrochemical noise data recorded for the AXJ530 specimens in the alkaline solution confirms the superiors properties of the passive film formed over the thixocast specimens, as compared to the die-cast specimen. Indeed, the amplitude of potential and current fluctuations decreased during the exposure in alkaline solution, which evidences a high stability over the immersion time, while the opposite was observed for the diecast specimens.…”

Section: Discussionsupporting

confidence: 71%

Electrochemical Study of AXJ530 Magnesium Alloy Behavior in Alkaline NaCl Solution

et al. 2007

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According to their low density, high strength/weight ratio, and good castability, magnesium alloys offer a variety of opportunities for structural applications in automotive and aeronautical industries. Among the magnesium alloy family, AZ91D is one of the most popular since it has good mechanical properties and behaves satisfactory under atmospheric and even marine environment. [1] However, AZ91D is unsuitable for use at temperatures above 120°C due to its poor creep resistance and low strength at elevated temperature. [2] Therefore, many new magnesium alloys have been developed to remedy this problem.The AXJ530 magnesium alloy, developed by General Motors R&D Center (MI, USA), is one of these promising alloys made to offer a good creep resistance at elevated temperature. [3] The corrosion behavior of die-cast AXJ530 specimens has been studied by cyclic salt spray corrosion test and the measured corrosion rates were found to be close to those of die-cast AZ91D specimens. [3] However, in order to better understand the involved corrosion mechanisms, it is important to examine the corrosion behavior of AXJ530 alloy in different conditions with more advanced electrochemical methods.In the present work, the corrosion properties of die-cast and thixocast specimens of AXJ530 magnesium alloy were studied in alkaline solution. Their corrosion performances were determined using potentiodynamic polarization method, electrochemical noise analysis (ENA), electrochemical impedance spectroscopy (EIS) and immersion tests. Figure 1 shows SEM micrographs of die-cast and thixocast AXJ530 specimens. The microstructure of die-cast specimens ( Fig. 1(a)) consists of primary a-Mg dendrites (dark) surrounded by eutectic constituent (light grey). Figures 1(b) and 1(c) show the typical microstructure of specimens obtained by thixocasting, characterized by a-Mg particles pre-existing in the semi-solid state, i.e. at 592°C. These particles are surrounded by a fine microstructure composed of primary a-Mg dendrites (dark) and eutectic (light grey). Previous studies have shown that the aluminum concentration in pre-existing a-Mg phase or primary a-Mg phase formed during the solidification range between 1.3 and 1.5 wt %. [4] The eutectic in both die-cast and thixocast specimens is composed of a-Mg phase and a (Mg,Al) 2 Ca compound. [5,6] Strontium-rich phases were also observed, but their exact stoichiometry is uncertain. Al-Mn particles (white) were also visible in all specimens. Figure 2 shows the polarization curves of AXJ530 specimens in alkaline solution. All specimens exhibit a self-passivation which indicates that a protective passive film forms immediately after immersion. Thixocast specimens (AXJ530-SFTC and AXJ530-ESTC) do not show well defined pitting potential, which usually marks the irreversible breakdown of the passive film. In this case, estimated pitting potentials were determined as the potentials for which a slight but visible hydrogen evolution was observed; these points (E pit ) are indicated on each polarization curve in ...

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Section: Discussionsupporting

confidence: 71%

Electrochemical Study of AXJ530 Magnesium Alloy Behavior in Alkaline NaCl Solution

et al. 2007

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“…Sulphur was detected by EDX in this carbon steel, and inclusions were visible by optical microscopy. Such a type of current transient, characterized by a quick rise followed by exponential decay, has also been observed during metastable pitting in other carbon steels [11,12] and in pure iron [32].…”

Section: Chronoamperometric Measurementsmentioning

confidence: 60%

“…The bicarbonate passivating medium has been used by Brossard et al to study the electrochemical behaviour of 1024 mild steel [8]; its localised corrosion was studied by adding chloride to bicarbonate and phosphate passivating media [9,10]. Cheng et al [11,12] also used bicarbonate solution with and without chloride to study metastable pit formation in A516 carbon steel, as well as in chromate/bicarbonate mixtures [13]. A number of studies have been undertaken with regard to identifying the passive film formed on iron in bicarbonate solutions using electrochemical impedance [14,15], and by spectroscopy and spectroelectrochemistry [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…Simard et al [8] showed that this film is not affected by the presence of HCO À 3 /CO 2À 3 as long as the applied potential remains in the passive region, since the oxidation current is practically independent of the HCO À 3 /CO 2À 3 concentration although other studies showed that this is pH and temperature dependent [25]. Pit nucleation and passivation of carbon steel [12,26] has also been assessed.…”

Section: Introductionmentioning

confidence: 99%

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Influence of alloying on the passive behaviour of steels in bicarbonate medium

Alves

Brett

2002

Corrosion Science

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The electrochemical behaviour of passive films on carbon steel, chromium steel and high speed steel (HSS) was studied in 0.5 M NaHCO 3 . The influence of the presence of 10 mM potassium chloride on passive film stability, and of the heat treatment of chromium steel and HSS on the respective film properties, was also investigated. Polarization curves showed that the alloy composition exerts a significant influence on the onset of passive film formation, chromium and HSSs passivating more easily as a result of the higher alloying content. Values of passive current, obtained both potentiodynamically and at fixed potential, were higher for HSS than for carbon and chromium steels, which was attributed to the contributions of Mo and W to the passive film composition. The presence of chloride ion delays the passivation of chromium and HSSs, but does not interfere with passive film stability, as shown by the chronoamperometric profile and passive current values. In the case of carbon steel, with no alloying elements, chloride ion diminishes film stability but does not influence passive film formation. Heat treatment, which alters the microstructure, does not alter the properties of the passive films except for a small effect on those formed potentiodynamically on HSS. Ó

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“…In recent years, electrochemical noise (EN) technique, due to its nonperturbation and simplicity, has been used to evaluate corrosion behavior of carbon steels in real time 6, 7. Therefore, in order to study some real‐time change and find some new phenomenon the EN is used to study the pitting corrosion of J55 steel in NaCl/NaHCO 3 electrolytes in the text.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical noise analysis of pitting corrosion of J55 steel in NaCl + NaHCO₃ electrolytes

Zhang

Zhao

2011

Surface & Interface Analysis

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Electrochemical noise (EN) was used to study the pitting corrosion of J55 steel in NaCl/NaHCO 3 electrolytes. Below critical ratio for Cl − to HCO − , the corrosion rate increased with added NaCl, and conversely, decreased above that level. Also, the critical ratio was between 1 and 1.66. The PSD for potential and current noise were linear and rather gently sloped. J55 casing steel was quite sensitive to NaCl/NaHCO 3 electrolytes.

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Analysis of the role of electrode capacitance on the initiation of pits for A516 carbon steel by electrochemical noise measurements

Cited by 62 publications

References 16 publications

Electrochemical Study of AXJ530 Magnesium Alloy Behavior in Alkaline NaCl Solution

Electrochemical Study of AXJ530 Magnesium Alloy Behavior in Alkaline NaCl Solution

Influence of alloying on the passive behaviour of steels in bicarbonate medium

Electrochemical noise analysis of pitting corrosion of J55 steel in NaCl + NaHCO₃ electrolytes

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Analysis of the role of electrode capacitance on the initiation of pits for A516 carbon steel by electrochemical noise measurements

Cited by 62 publications

References 16 publications

Electrochemical Study of AXJ530 Magnesium Alloy Behavior in Alkaline NaCl Solution

Electrochemical Study of AXJ530 Magnesium Alloy Behavior in Alkaline NaCl Solution

Influence of alloying on the passive behaviour of steels in bicarbonate medium

Electrochemical noise analysis of pitting corrosion of J55 steel in NaCl + NaHCO3 electrolytes

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Electrochemical noise analysis of pitting corrosion of J55 steel in NaCl + NaHCO₃ electrolytes