Investigation of the Corrosion and Passivation Processes of Magnesium in the Molten 2 HF  ‐  KF  Mixture by AC Impedance Spectroscopy

Rouquette, Sébastien; Ferry, D.; Picard, Gauthier

doi:10.1149/1.2096442

Cited by 13 publications

(11 citation statements)

References 3 publications

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“…The anodic reaction sequence leading to MgF 2 film formation has also been established [119]. A comparative study of the corrosion behaviour of magnesium and copper in KF-2HF shows that magnesium is more stable in low temperature melts with higher HF content.…”

Section: Magnesiummentioning

confidence: 94%

Electrochemistry of metals and semiconductors in fluoride media

Noel

Suryanarayanan

2005

J Appl Electrochem

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The electrochemical surface transformations and diverse applications of a variety of metals and semiconductors in a wide range of fluoride media such as aqueous, non-aqueous media, liquid HF media, room temperature fluoride melts and molten fluoride media with a melting range covering 50-1000°C are reviewed. Nickel shows excellent corrosion resistance in the absence of water. The anodic performance of this metal in electrochemical perfluorination and NF 3 production is discussed. Compact carbon materials serve as anodes in fluorine generators. In high temperature melts, they perform as consumable anodes. Graphitic carbon undergoes intercalation/ de-intercalation process and related battery applications. Cu/CuF 2 couple is a good reference electrode. Pt and vitreous carbon materials are the inert electrodes of choice for electro analytical applications. Electrodeposition of Lithium as a non-dendritic uniform phase is important in Lithium metal based secondary batteries. High temperature fluoride melts are used in electro-deposition of valve metals such as Nb, Ta, and Ti. The stability and decomposition of fluoride complexes in these media are of interest.

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Section: Magnesiummentioning

confidence: 94%

Electrochemistry of metals and semiconductors in fluoride media

Noel

Suryanarayanan

2005

J Appl Electrochem

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“…[30][31][32][33][34][35] It requires considering the kinetic equations of all the steps of the mechanism.…”

Section: -Diffusion Of Watermentioning

confidence: 99%

“…It is equivalent to Warburg impedance 30 and presents the term (jω) −0.5 characteristic of a diffusion. Taking into account of the double layer capacitance (characteristic of the capacitive current [30][31][32][33][34][35][36] ) the global electrical circuit defined for this system is given in Figure 6. The analytical expressions of all the electrical parameters involving in the faradaic impedance are gathered in Table II.…”

Section: R T1 K A1mentioning

confidence: 99%

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Kinetic Model of Aluminum Behavior in Cement-Based Matrices Analyzed by Impedance Spectroscopy

Delpech¹,

Cannes²,

Barré³

et al. 2017

J. Electrochem. Soc.

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Aluminum reactivity in cement-based matrices, generally used for conditioning low-and intermediate-level radioactive wastes, is a problem due to dihydrogen produced by the corrosion reaction which depends on the pH of the pore solution. Electrochemical impedance spectroscopy has been used to propose a mechanism for aluminum corrosion in cementitious matrices based on ordinary Portland cement (OPC, pH ≈ 13) or magnesium phosphate cement (MKP, pH ranging between 4 and 9) containing or not LiNO 3 as a corrosion inhibitor. The fit of impedance diagrams recorded on aluminum electrode as a function of time has been realized using electrical parameters to model the cement and kinetic constants for the faradaic impedance. The so determined kinetic constants are used to calculate the corrosion current and the dihydrogen production as a function of time. Comparison of these results with experimental measurements of dihydrogen release obtained by gas chromatography shows a very good agreement except in the MKP matrix containing LiNO 3 . In the OPC matrix, dihydrogen production is between 500 and 1000 times higher than in the MKP matrix, which put in evidence the significant benefit in using MKP cements for aluminum encapsulation. It has long been common practice to stabilize and solidify lowand intermediate-level radioactive wastes using cement before sending them to disposal.1-3 The wastes are confined with a cement or a mortar in a steel container which is closed. Ordinary Portland Cement (OPC) is one of the most widely used materials for conditioning radioactive wastes. Indeed, it is inexpensive, it can be easily supplied and, after hydration, it can exhibit high stability over time. 4 However, wastes produced by nuclear activities are very diverse and, under certain circumstances, can chemically react with cementbased phases or aqueous interstitial solution, thus reducing the quality of the conditioning material. For instance, the dismantling of old nuclear reactors generates a large volume of low and intermediate-level wastes, some of them containing metallic aluminum. Aluminum is a reactive amphoteric metal, forming a protective oxide layer on contact with air or water. This layer is generally stable in the pH range 4-9. [5][6][7] However, in a strongly alkaline medium, such as that encountered in conventional cementitious materials based on OPC, this layer is soluble, resulting in continued corrosion with associated liberation of dihydrogen. Then, the use of Portland cement to encapsulate large amounts of aluminum is prohibited. The formation of dihydrogen contributes to increase the pressure in the container which is able to crack. It is the reason why the main criterion for metallic waste management is based on the volume of dihydrogen production.In this context, our work concerns the aluminum reactivity in cement-based matrices for conditioning radioactive wastes. To overcome the Al corrosion, the strategy proposed consists in (i) replacing OPC by an alternative mortar leading to a pore solution with an appropria...

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“…Thus, EIS was introduced to study hot corrosion in the 1980s. But only limited progresses have been achieved in this aspect, especially in the establishment of models for fitting the impedance data [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Moreover, electrochemical measurements of hot corrosion were conducted mostly in deep molten salts, which are quite different from the thin films of fused salts occurring in practical industrial environments.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Impedance Study of Hot Corrosion of the Mo-Rich Ni3Al-Base Alloy IC6 at 750–800 °C Beneath Solid Na2SO4 Deposits

2011

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A two-electrode probe was used for electrochemical impedance studies of hot corrosion kinetics of molybdenum-containing Ni 3 Al-base alloy IC6 covered with a solid Na 2 SO 4 film at 750 and 800°C in air. The alloy was subject to catastrophic corrosion at both temperatures, forming a thick porous oxide layer, as a result of the formation of Na 2 MoO 4 -MoO 3 -Na 2 SO 4 melt. The experimental temperature affected the formation of the melt, the ionic conduction of the corrosion layer, and thus the impedance characteristics. For the corrosion at 800°C the Nyquist plots were composed of two capacitive loops at high-mid frequency and a line at low frequency indicating a diffusion-controlled reaction. At 750°C, however, the plots consisted of a single capacitive loop in the initial stage, followed by the same impedance features as at 800°C. Two equivalent circuits were proposed to fit the impedance spectra at the two temperatures. Based on the precise measurements of diffusion impedance, the diffusion flux of oxygen through the salt layer was calculated, and the main reduction reaction was also discussed.

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Investigation of the Corrosion and Passivation Processes of Magnesium in the Molten 2 HF ‐ KF Mixture by AC Impedance Spectroscopy

Cited by 13 publications

References 3 publications

Electrochemistry of metals and semiconductors in fluoride media

Electrochemistry of metals and semiconductors in fluoride media

Kinetic Model of Aluminum Behavior in Cement-Based Matrices Analyzed by Impedance Spectroscopy

Electrochemical Impedance Study of Hot Corrosion of the Mo-Rich Ni3Al-Base Alloy IC6 at 750–800 °C Beneath Solid Na2SO4 Deposits

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