Corrosion Resistance and Mechanical Stability of Nickel Alloys in Molten-Salt Nuclear Reactors

Surenkov, A. I.; Ignat’ev, V. V.; Abalin, S. S.; Konakov, S. A.; Uglov, V. S.

doi:10.1007/s10512-018-0372-y

Cited by 16 publications

(7 citation statements)

References 7 publications

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“…The first experiments were conducted on workpieces produced from easy-to-process conductive materials with a low melting point. Workpieces with dimensions of 200 × 20 × 16 mm of sorted and gauged corrosion-resistant, heat-resistant, and high-temperature steel of 12KH18N10T grade (analogue of AISI 321, specifications by interstate standard GOST 5949-75) [83, 84, 85, 86, 87, 88] and 200 × 16 × 16 mm of D16 aluminium alloy (AlCu4Mg1, analogue of AISI 2024) [89, 90, 91, 92, 93, 94] were used.…”

Section: Methodsmentioning

confidence: 99%

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

Grigoriev

Kozochkin

Porvatov

et al. 2019

Heliyon

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The productivity of electrical discharge machining (EDM) is relatively low owing to the natural laws of electrical erosion. Precise EDM demands uninterrupted control of the discharge gap and adjustment of process parameters. It is particularly critical for processing large workpieces with complex linear surfaces and for materials with threshold conductivities such as the new advanced ceramic nanocomposites Al2O3+TiC and Al2O3+SiCw+TiC(30–40%). In these cases, adequate flushing of erosion products is hampered by the geometry of the working space or by the small value of the required discharge gap, which does not exceed 2.2–2.5 μm. The methods of adaptive control in modern computer numerical control systems of EDM equipment based on measuring the electrical parameters in the working zone have been shown to be ineffective in the cases described above. This study aims to investigate the natural phenomena of material sublimation under discharge pulses for conductive ceramics and nanocomposites. The measured conductivities of the samples are higher than the percolation threshold. However, the question of machinability remains open owing to detected processing interruptions and poor quality of machined surfaces. New knowledge on EDM of conductive ceramics and nanocomposites can improve the final quality of the machined surfaces and productivity of the method by the introduction of advanced monitoring and control methods based on acoustic emissions. The manuscript presents an up-to-date overview and current state of the research on the subject area. The obtained morphology of the samples and discussion of the findings complete the experimental part of the study. The scientific basis for a new type of adaptive control system is provided. This can improve the effectiveness of parameter control for machining conductive ceramics and nanocomposites and contribute to an increase in the EDM performance for the most critical cases.

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Section: Methodsmentioning

confidence: 99%

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

Grigoriev

Kozochkin

Porvatov

et al. 2019

Heliyon

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“…There are several examples in which modifying the FLiNaK salt chemistry has reduced the amount of mass transport or intergranular Cr depletion of Ni-based alloys. [32][33][34][35] Zhou et al 36 reported that Ni-20Cr foils in contact with FLiNaK containing 5 wt% UF 3 showed less intragranular corrosion in the salt-facing surface when the material was proton irradiated. It is speculated that irradiation of the salt in the local area may cause it to be so oxidizing that uniform corrosion of the matrix occurs rather than intragranular corrosion.…”

Section: Resultsmentioning

confidence: 99%

Potentiodynamic Polarization of Pure Metals and Alloys in Molten LiF-NaF-KF (FLiNaK) Using the K/K⁺ Dynamic Reference Electrode

Doniger

Couet

Sridharan

2022

J. Electrochem. Soc.

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The potentiodynamic polarization method using the K/K+ dynamic reference electrode was used to understand the corrosion behavior of Ni, Fe, Cr, the Ni-20Cr binary alloy, and 316L stainless steel in molten 46.5LiF 11.5NaF-42KF (FLiNaK, composition in mol %) salt at 700˚C. Exposure of the materials without an applied potential revealed that Ni and Fe were stable in FLiNaK, but Cr was dissolved rapidly. The apparent redox potentials of each material with respect to the K/K+ redox couple are compared to gain insight into how the applied potential relates to the dominant corrosion mechanism for each alloy. The polarized pure metals experienced uniform surface recession while corrosion in the alloys resulted in preferential elemental dissolution depending on the applied potential with respect to the K/K+ reference reaction.

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“…Molybdenum electrodes (1) and molybdenum current led (3) to the nickel (9) and iron (11) electrodes and were screened using alundum straws (2). Molybdenum end cup electrodes were screened from the melt with nitride boron tubes (10). The potentials were measured between the beryllium dynamic electrode and metallic iron electrode (11), which were in equilibrium with their ions in the (Fe 2+ ) melt.…”

Section: Equilibrium Potentials Measurementmentioning

confidence: 99%

“…Such materials are supposed to demonstrate low vapor pressure in a wide range of operating temperatures from 500 to 850 • C and do not interact with the fuel in cases of leakage [3][4][5][6][7]. Special attention should be paid to the corrosion resistance of construction materials in fluoride salts [8][9][10][11]. Research devoted to the search for materials resistant to fluoride melts is currently being studied [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Interaction between Iron Fluoride and Molten FLiBe

et al. 2022

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The equilibrium potentials of iron in a LiF-BeF2-FeF2 melt were measured using the EMF method and were dependent upon the temperature and iron fluoride concentrations. The empirical equations for the isotherms and equilibrium polytherms of the iron fluoride concentration were obtained. The cathode polarization of iron fluoride in the molten mixture of lithium and beryllium fluoride was measured using the current switch off method from the stationary state. It was found that in the studied temperature and concentration ranges of iron fluoride in the LiF-BeF2 electrolyte, the valence state of iron in the melt is mainly +2. According to the experimental values of the equilibrium potentials of the iron electrode in the LiF-BeF2-FeF2 melt, the conditional standard potentials of iron were calculated relative to the fluoride reference electrode in the molten mixture of lithium and beryllium fluoride. The conditional standard values of the Gibbs energy change were calculated at the formation of iron difluoride from the element in the form of dilute solutions, as were the thermodynamic values (enthalpy and entropy) when iron difluoride was mixed with LiF-BeF2.

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Corrosion Resistance and Mechanical Stability of Nickel Alloys in Molten-Salt Nuclear Reactors

Cited by 16 publications

References 7 publications

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

Potentiodynamic Polarization of Pure Metals and Alloys in Molten LiF-NaF-KF (FLiNaK) Using the K/K⁺ Dynamic Reference Electrode

Interaction between Iron Fluoride and Molten FLiBe

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Corrosion Resistance and Mechanical Stability of Nickel Alloys in Molten-Salt Nuclear Reactors

Cited by 16 publications

References 7 publications

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

Potentiodynamic Polarization of Pure Metals and Alloys in Molten LiF-NaF-KF (FLiNaK) Using the K/K+ Dynamic Reference Electrode

Interaction between Iron Fluoride and Molten FLiBe

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Potentiodynamic Polarization of Pure Metals and Alloys in Molten LiF-NaF-KF (FLiNaK) Using the K/K⁺ Dynamic Reference Electrode