Redox Potential Measurements of Cr(II)/Cr Ni(II)/Ni and Mg(II)/Mg in Molten MgCl<sub>2</sub>–KCl–NaCl Mixture

Zhang, Mingyang; Ge, Jianbang; Yin, Ting; Zhang, Jinsuo

doi:10.1149/1945-7111/aba15a

Cited by 10 publications

(11 citation statements)

References 24 publications

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“…Note that the initiation of the pores occurred at specific locations, and future work can be carried out to further investigate the onset of corrosion at the metal–salt interface. The degradation of Ni–20Cr occurred due to the preferential dissolution of Cr because the redox potentials of Cr(II)/Cr and Cr(III)/Cr are lower than those of Ni(II)/Ni in molten chloride salt. , Interestingly, the sample surface morphology changed with the reaction time.…”

Section: Resultsmentioning

confidence: 99%

Temperature-Dependent Morphological Evolution during Corrosion of the Ni-20Cr Alloy in Molten Salt Revealed by Multiscale Imaging

Liu

Bawane

Zheng

et al. 2023

ACS Appl. Mater. Interfaces

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Understanding the mechanisms leading to the degradation of alloys in molten salts at elevated temperatures is significant for developing several key energy generation and storage technologies, including concentrated solar and next-generation nuclear power plants. Specifically, the fundamental mechanisms of different types of corrosion leading to various morphological evolution characteristics for changing reaction conditions between the molten salt and alloy remain unclear. In this work, the three-dimensional (3D) morphological evolution of Ni–20Cr in KCl–MgCl2 is studied at 600 °C by combining in situ synchrotron X-ray and electron microscopy techniques. By further comparing different morphology evolution characteristics in the temperature range of 500–800 °C, the relative rates between diffusion and reaction at the salt–metal interface lead to different morphological evolution pathways, including intergranular corrosion and percolation dealloying. In this work, the temperature-dependent mechanisms of the interactions between metals and molten salts are discussed, providing insights for predicting molten salt corrosion in real-world applications.

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Section: Resultsmentioning

confidence: 99%

Temperature-Dependent Morphological Evolution during Corrosion of the Ni-20Cr Alloy in Molten Salt Revealed by Multiscale Imaging

Liu

Bawane

Zheng

et al. 2023

ACS Appl. Mater. Interfaces

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“…The pseudo-binary and pseudo-ternary systems assessed in this work together with the models of Robelin et al only lack solution models of the MgCl 2 –CrCl 2 , NaCl–MgCl 2 –CrCl 2 , and KCl–MgCl 2 –CrCl 2 systems for a complete pseudo-quaternary description. We have developed this first-time pseudo-quaternary model from the joint assessment of the phase equilibria of MgCl 2 –CrCl 2 and the EM measurements for dilute CrCl 2 in the NaCl–MgCl 2 , KCl–MgCl 2 , and NaCl–KCl–MgCl 2 systems …”

Section: Resultsmentioning

confidence: 99%

Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Yingling

Aziziha

Schorne-Pinto

et al. 2023

ACS Appl. Energy Mater.

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The formation of corrosion species in molten salt reactor systems is driven by the salt redox condition, which can be indicated by the uranium oxidation state ratio (U4+/U3+). In chloride salts, chromium is well known to have the highest tendency to deplete from alloy surfaces; however, no available thermodynamic database suitably represents the effect of trivalent and tetravalent uranium chloride on the corrosion potential. In this work, we extend the Molten Salt Thermal Properties Database–Thermochemical with Gibbs energy models suitable for application to alloy corrosion in chloride molten salt-fueled nuclear reactors. The work required the development of fully constrained thermodynamic models, utilizing the modified quasi-chemical model in the quadruplet approximation for the melt and a single sublattice model for the solid solution phases allowing accurate estimations of thermodynamic properties even in systems for which few thermodynamic data are available. The effort included differential scanning calorimetry (DSC) measurements to find the previously unreported phase equilibria of the CrCl2–UCl3 system and to confirm the equilibria of the MgCl2–UCl3 system. Elemental period correlations allowed the estimation of thermodynamic values for compounds in the NaCl–CrCl2 and KCl–CrCl2 systems allowing a well-informed description of CrCl2 behavior in the compositions of technical interest for the Na–K–Mg–U3+–U4+ chloride salt.

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“…Here, n = 2 corresponds to a potential mechanism where Ni also dissolves slightly into the molten salt, and then redeposits back into the structure. The limited dissolution concentration of NiCl 2 in MgCl 2 –KCl–NaCl (44.13/22.79/33.08 mol%) is 1.85 × 10 −17, 72 , namely, this is considering the equilibrium between Ni and NiCl 2 in a pure chloride melt. While miniscule, this slight solubility allows some amount of Ni to be transported in the melt.…”

Section: Resultsmentioning

confidence: 99%

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

Liu

Ronne

et al. 2021

Nat Commun

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Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.

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Redox Potential Measurements of Cr(II)/Cr Ni(II)/Ni and Mg(II)/Mg in Molten MgCl₂–KCl–NaCl Mixture

Cited by 10 publications

References 24 publications

Temperature-Dependent Morphological Evolution during Corrosion of the Ni-20Cr Alloy in Molten Salt Revealed by Multiscale Imaging

Temperature-Dependent Morphological Evolution during Corrosion of the Ni-20Cr Alloy in Molten Salt Revealed by Multiscale Imaging

Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

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Redox Potential Measurements of Cr(II)/Cr Ni(II)/Ni and Mg(II)/Mg in Molten MgCl2–KCl–NaCl Mixture

Cited by 10 publications

References 24 publications

Temperature-Dependent Morphological Evolution during Corrosion of the Ni-20Cr Alloy in Molten Salt Revealed by Multiscale Imaging

Temperature-Dependent Morphological Evolution during Corrosion of the Ni-20Cr Alloy in Molten Salt Revealed by Multiscale Imaging

Thermodynamic Assessment of CrCl2 with NaCl–KCl–MgCl2–UCl3–UCl4 for Molten Chloride Reactor Corrosion Modeling

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

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Redox Potential Measurements of Cr(II)/Cr Ni(II)/Ni and Mg(II)/Mg in Molten MgCl₂–KCl–NaCl Mixture

Thermodynamic Assessment of CrCl₂ with NaCl–KCl–MgCl₂–UCl₃–UCl₄ for Molten Chloride Reactor Corrosion Modeling