Pitting corrosion of AZ91D and AJ62x magnesium alloys in alkaline chloride medium using electrochemical techniques

Lafront, A.-M.; Zhang, W.; Jin, S.; Tremblay, R.; Dubé, D.; Ghali, Edward

doi:10.1016/j.electacta.2005.05.013

Cited by 95 publications

(49 citation statements)

References 14 publications

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“…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.…”

mentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

“…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.…”

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confidence: 99%

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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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Corrosion Behavior of AZ31 Magnesium Alloy in Dilute Sodium Chloride Solutions

Wang

Shinohara

Zhang

2009

ZAKAEP

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“…In test, if the potential that reverses from the cathode side to the anode side is E corr (c) , AZ31 indicates the lowest current density in the anode region wherein the potential is higher than E corr(c) , and its curve characteristics are different from those of DLC/AZ31 specimens. AZ31 shows a rapid increase in current density near −1.4 V, which is most likely due to pitting [25,26] at −1.4 V. As opposed to this, the DLC/AZ31 samples show no rapid increase in current density, which suggests different progressions of corrosion. The corrosion characteristics will be described in detail in Clause 3.3 along with images of the specimen surfaces observed after the test.…”

Section: Anodic Polarization Curvesmentioning

confidence: 54%

Electrochemical Polarization Characteristics of a DLC-Coated Magnesium Alloy Stent in a Saline Solution

Nakatani

Fukumoto

Wada³

et al. 2017

J. Photopol. Sci. Technol.

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One of the major problems encountered when using bioabsorbable magnesium alloy stents is their loss of strength over time, which is due to their high elution rates. Although the use of a diamond-like carbon (DLC) coating to overcome this drawback, the excellent biocompatibility of which has been confirmed, is drawing attention, research on its application to magnesium alloy stents is still scarce. The present research aims to verify the corrosion characteristics of DLC-coated magnesium alloys to establish a DLC coating technique that will allow controlling the decomposition rate of bioabsorbable magnesium alloys. DLC films were formed using a 13.56 MHz radio-frequency (RF) plasma chemical vapor deposition (CVD) apparatus, and the corrosion characteristics were verified using electrochemical measurements. The results of the experiments reveal that a DLC coating decreases the corrosion current density in comparison to an untreated magnesium alloy and that the inhibition of localized corrosion is possible. Application of this DLC coating is expected to provide a stent that is capable of preventing fractures caused by localized corrosion and to enable the control of the decomposition rate.

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“…The insoluble corrosion product on the surface of the alloy could slow down the corrosion rate [20]. Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of chloride ion concentration, spraying time and pH values on corrosion behavior of friction stir welded AZ61A magnesium alloy welds in salt fog environments

Dhanapal¹,

Boopathy²,

Balasubramanian³

2013

uujms

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The present research devoted to the investigation of the corrosion behavior of AZ61A FSW welds in accelerated conditions, including the influence of salt fog environmental parameters such as chloride ion concentration, pH, and duration of exposure. Significant numbers of tests were carried out that make possible to create the regression model (empirical equation) of influence of selected environmental parameters on corrosion rate. The corrosion products were analyzed by SEM and XRD analysis. This research demonstrates the effect of chloride ion concentrations, spraying time and pH values on corrosion rate, and it show the corrosion activity decelerates with the increasing pH value and spraying time respectively. It was found that the increase in chloride ion concentration accelerates the corrosion of AZ61A weldments. The corrosion morphology was predominantly influenced by the distribution of β-phase (e.g. Mg17Al12 intermetallic).

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Pitting corrosion of AZ91D and AJ62x magnesium alloys in alkaline chloride medium using electrochemical techniques

Cited by 95 publications

References 14 publications

Corrosion Behavior of AZ31 Magnesium Alloy in Dilute Sodium Chloride Solutions

Corrosion Behavior of AZ31 Magnesium Alloy in Dilute Sodium Chloride Solutions

Electrochemical Polarization Characteristics of a DLC-Coated Magnesium Alloy Stent in a Saline Solution

Effect of chloride ion concentration, spraying time and pH values on corrosion behavior of friction stir welded AZ61A magnesium alloy welds in salt fog environments

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