Alloying effects in high temperature molten salt corrosion

Ghaznavi, Touraj; Bryk, M.; Persaud, S.Y.; Newman, R.C.

doi:10.1016/j.corsci.2021.110003

Cited by 38 publications

(50 citation statements)

References 90 publications

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“…[ 50 ] However, in a hot alkaline solution, the Cr oxide layer is highly unstable and is easily transformed into CrO 4 2− because of the reducing environment, which accelerates the selective dissolution of Cr and Fe ions from the remaining exposed Ni alloy substrate by galvanic corrosion. [ 24 ]…”

Section: Resultsmentioning

confidence: 99%

“…Without Ni enrichment on the SCR surface by the selective electrochemical dissolution process, no active refresh process occurred in the Ni‐SCR because the driving force for galvanic corrosion was insufficient when the concentration of Ni on the surface region was low and the parting limit for dealloying was not satisfied, which led to no activity toward CO 2 methanation even after immersion Ni‐SCR in 50 wt% NaOH solution for 12 h (Figure 4a). [ 24 ] Consequently, the refresh process for used Ni‐SCR facilitated the selective dissolution of Cr, Fe, and Mo to expose fresh Ni(OH) 2 within a short time (Table S7, Supporting Information). Similarly, a third long‐term stability test after the second refresh process also showed overperformance compared with the second reaction, including an 83.4% CO 2 conversion rate and a 99.9% CH 4 selectivity; these results indicate that the CO 2 methanation activity continuously increased with increasing number of refresh processes and that the stability remained high (average 1.48% reduction in CO 2 conversion rate).…”

Section: Resultsmentioning

confidence: 99%

“…[21,23] By contrast, Cr, Fe, and Mo species were thermodynamically unstable and selectively dissolved as CrO 4 2− , Fe(OH) 4 − , and MoO 4 2− , respectively. [24][25][26] SEM images subsequently acquired for Ni-SCR specimens subjected to applied potentials between 200 and 360 mV Hg/HgO showed that the surface Ni(OH) 2 transformed into agglomerated species. The change in morphology and disappearance of the Ni(OH) 2 peak in the XRD pattern implied that Ni(OH) 2 was transformed into Ni 3+ species (e.g., NiO x (OH) 2−2x and NiOOH) because of the increase of the oxidation degree with increasing polarization.…”

Section: Selective Electrochemical Dissolution For Different Applied ...mentioning

confidence: 99%

“…2− because of the reducing environment, which accelerates the selective dissolution of Cr and Fe ions from the remaining exposed Ni alloy substrate by galvanic corrosion. [24] To comprehensively investigate the galvanic corrosion between Ni and Ni-SCRs, we conducted a zero-resistance ammeter test to demonstrate that the amount of exposed Ni on the Ni-SCR substrates accelerates galvanic corrosion via small anode-large cathode coupling, in which the high overpotential was applied to the small anode (Figure S17, Supporting Information). The variation of the surface area ratio between pure Ni and the Ni-SCR substrate from 1 to 10 resulted in a proportional increase in the galvanic corrosion density from 10.4 to 48.2 μA cm −1 (Figure S18, Supporting Information).…”

Section: Refreshment Of Ni-scrmentioning

confidence: 99%

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Robust Self‐Catalytic Reactor for CO₂ Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Kim

Mori

Nakano

et al. 2023

Adv Funct Materials

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The methanation of CO2 has been actively pursued as a practical approach to mitigating global climate change. However, the complexity of the catalyst development process has hindered the development of new catalysts for CO2 methanation; as a result, few catalysts are commercially available. Herein, a multifunctional self‐catalytic reactor (SCR) is prepared via metal 3D printing and selective electrochemical dissolution as a method to not only simplify the catalyst development process but also fabricate active catalysts for CO2 methanation. The combination of metal 3D printing and selective electrochemical dissolution is demonstrated as a feasible method to prepare active catalysts for the methanation of CO2 in a short time. In addition, the use of an electrochemical method enables the formation of galvanic cells on the SCR; these cells continuously generate active sites via self‐dissolution during a simple refresh process, resulting in high reusability of the SCR. The proposed method represents a new facile technique to fabricate highly reusable catalysts that exhibit superior performance for CO2 methanation, and the results provide a guideline for preparing metal 3D‐printed catalysts that will satisfy industrial demand.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Selective Electrochemical Dissolution For Different Applied ...mentioning

confidence: 99%

Section: Refreshment Of Ni-scrmentioning

confidence: 99%

See 2 more Smart Citations

Robust Self‐Catalytic Reactor for CO₂ Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Kim

Mori

Nakano

et al. 2023

Adv Funct Materials

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“…According to their redox potentials, Cr can be corroded preferentially from an alloy into the molten salt compared with Ni, indicating that Ni-Cr alloy would be a suitable binary alloy for molten salt dealloying 28,35 . Pore formation in Ni-based structural alloys has been observed in studying microstructural evolution in the context of molten salt corrosion studies 36,37 , but the emphasis has not been chiefly on dealloying or nanoporous material fabrication.…”

mentioning

confidence: 99%

Evolution of micro-pores in Ni–Cr alloys via molten salt dealloying

Clark

Liu

et al. 2022

Sci Rep

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Porous materials with high specific surface area, high porosity, and high electrical conductivity are promising materials for functional applications, including catalysis, sensing, and energy storage. Molten salt dealloying was recently demonstrated in microwires as an alternative method to fabricate porous structures. The method takes advantage of the selective dissolution process introduced by impurities often observed in molten salt corrosion. This work further investigates molten salt dealloying in bulk Ni–20Cr alloy in both KCl–MgCl2 and KCl–NaCl salts at 700 ℃, using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction (XRD), as well as synchrotron X-ray nano-tomography. Micro-sized pores with irregular shapes and sizes ranging from sub-micron to several microns and ligaments formed during the process, while the molten salt dealloying was found to progress several microns into the bulk materials within 1–16 h, a relatively short reaction time, enhancing the practicality of using the method for synthesis. The ligament size increased from ~ 0.7 μm to ~ 1.3 μm in KCl–MgCl2 from 1 to 16 h due to coarsening, while remaining ~ 0.4 μm in KCl–NaCl during 16 h of exposure. The XRD analysis shows that the corrosion occurred primarily near the surface of the bulk sample, and Cr2O3 was identified as a corrosion product when the reaction was conducted in an air environment (controlled amount sealed in capillaries); thus surface oxides are likely to slow the morphological coarsening rate by hindering the surface diffusion in the dealloyed structure. 3D-connected pores and grain boundary corrosion were visualized by synchrotron X-ray nano-tomography. This study provides insights into the morphological and chemical evolution of molten salt dealloying in bulk materials, with a connection to molten salt corrosion concerns in the design of next-generation nuclear and solar energy power plants.

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Applying state‐of‐the‐art microscopy techniques to understand the degradation of copper for nuclear waste canisters

Persaud

Binns

Guo

et al. 2023

Materials & Corrosion

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The metallurgy, mechanical properties, and corrosion of Cu, proposed as the corrosion barrier for Canadian used fuel containers (UFCs) for use in a deep geological repository (DGR), have been studied for decades. Bulk properties have been reported, and the knowledge applied to strengthen the performance of Cu produced by electrodeposition and cold spray. Despite this success, many degradation mechanisms are unclear from bulk testing, which cannot capture nanoscale phenomena driving degradation. This study provides examples using state‐of‐the‐art microscopy to understand mechanisms of Cu degradation, specifically for UFCs. Subtle changes in the electrodeposited Cu microstructure due to oxygen segregation are observed using atom probe tomography (APT). In aggressive sulfide‐containing environments, corrosion of the cold‐sprayed Cu occurs along particle–particle interfaces, likely inherent to the manufacturing process. Microscale tensile testing at particle–particle interfaces confirms brittle cracking in the cold‐sprayed Cu. Although experiments are not consistent with DGR conditions, results do warrant further study on the performance of the cold‐sprayed Cu in particular.

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Alloying effects in high temperature molten salt corrosion

Cited by 38 publications

References 90 publications

Robust Self‐Catalytic Reactor for CO₂ Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Robust Self‐Catalytic Reactor for CO₂ Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Evolution of micro-pores in Ni–Cr alloys via molten salt dealloying

Applying state‐of‐the‐art microscopy techniques to understand the degradation of copper for nuclear waste canisters

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Alloying effects in high temperature molten salt corrosion

Cited by 38 publications

References 90 publications

Robust Self‐Catalytic Reactor for CO2 Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Robust Self‐Catalytic Reactor for CO2 Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Evolution of micro-pores in Ni–Cr alloys via molten salt dealloying

Applying state‐of‐the‐art microscopy techniques to understand the degradation of copper for nuclear waste canisters

Contact Info

Product

Resources

About

Robust Self‐Catalytic Reactor for CO₂ Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution

Robust Self‐Catalytic Reactor for CO₂ Methanation Fabricated by Metal 3D Printing and Selective Electrochemical Dissolution