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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Galvanic cell for processing of used nuclear fuel

A galvanic cell and methods of using the galvanic cell is described for the recovery of uranium from used nuclear fuel according to an electrofluorination process. The galvanic cell requires no input energy and can utilize relatively benign gaseous fluorinating agents. Uranium can be recovered from used nuclear fuel in the form of gaseous uranium compound such as uranium hexafluoride, which can then be converted to metallic uranium or UO.sub.2 and processed according to known methodology to form a useful product, e.g., fuel pellets for use in a commercial energy production system.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Electrochemical fluorination for processing of used nuclear fuel

A galvanic cell and methods of using the galvanic cell is described for the recovery of uranium from used nuclear fuel according to an electrofluorination process. The galvanic cell requires no input energy and can utilize relatively benign gaseous fluorinating agents. Uranium can be recovered from used nuclear fuel in the form of gaseous uranium compound such as uranium hexafluoride, which can then be converted to metallic uranium or UO.sub.2 and processed according to known methodology to form a useful product, e.g., fuel pellets for use in a commercial energy production system.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2012

Analysis and methodology for measuring oxygen concentration in liquid sodium with a plugging meter

Oxygen concentration in liquid sodium is a critical measurement in assessing the potential for corrosion damage in sodium-cooled fast reactors (SFRs). There has been little recent work on sodium reactors and oxygen detection. Thus, the technical expertise dealing with oxygen measurements within sodium is no longer readily available in the U.S. Two methods of oxygen detection that have been investigated are the plugging meter and the galvanic cell. One of the overall goals of the Univ. of Wisconsin's sodium research program is to develop an affordable, reliable galvanic cell oxygen sensor. Accordingly, attention must first be dedicated to a well-known standard known as a plugging meter. Therefore, a sodium loop has been constructed on campus in effort to develop the plugging meter technique and gain experience working with liquid metal. The loop contains both a galvanic cell test section and a plugging meter test section. Consistent plugging results have been achieved below 20 [wppm], and a detailed process for achieving effective plugging has been developed. This paper will focus both on an accurate methodology to obtain oxygen concentrations from a plugging meter, and on how to easily control the oxygen concentration of sodium in a test loop. Details of the design, materials, manufacturing, and operation will be presented. Data interpretation will also be discussed, since a modern discussion of plugging data interpretation does not currently exist. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2014

Atomic-scale decoration for improving the pitting corrosion resistance of austenitic stainless steels

Stainless steels are susceptible to the localized pitting corrosion that leads to a huge loss to our society. Studies in the past decades confirmed that the pitting events generally originate from the local dissolution in MnS inclusions which are more or less ubiquitous in stainless steels. Although a recent study indicated that endogenous MnCr 2 O 4 nano-octahedra within the MnS medium give rise to local nano-galvanic cells which are responsible for the preferential dissolution of MnS, effective solutions of restraining the cells from viewpoint of electrochemistry are being tantalizingly searched. Here we report such a galvanic corrosion can be greatly resisted via bathing the steels in Cu 2+ -containing solutions. This chemical bath generates Cu 2–δ S layers on the surfaces of MnS inclusions, invalidating the nano-galvanic cells. Our study provides a low-cost approach via an atomic scale decoration to improve the pitting corrosion resistance of stainless steels in a volume-treated manner.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Corrosion behaviors of friction welded dissimilar aluminum alloys

Highlights: • Corrosion properties of friction welded dissimilar aluminum alloys seem to be governed by the anode part in the weld. • Intense corrosion near the interface has the limited region due to insufficient ionic transport. • Self-formation of a micro-galvanic cell is a main reason for the inferior corrosion performance. - Abstract: Corrosion behaviors of the friction welded dissimilar aluminum alloys were investigated to understand how galvanic effect plays a role in altering corrosion properties of the dissimilar weld. From the fact that the weld had the similar OCP value to that of AA2017, it can be inferred that the corrosion characteristics of the weld is under the control of the AA2017 part in the weld and as a result, only the AA2017 part in the weld had experienced severe corrosion, leaving AA6063 under cathodic protection. Intense corrosion occurring near the interface implies that the area near the interface is placed under the effect of galvanic corrosion and there was the effective distance where the galvanic effect exerts an impact due to the increase in the resistance of the electrolyte with the distance from the interface. The disappearance of Warburg diffusion plot in Nyquist plots for the weld seemed to be the breakdown of the passivation layer related to the formation of the micro-galvanic cell, which in turn presented the shrinkage in the capacitance response, indicating that charge reactions in the form of corrosion occurred.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Effect of aqueous‐based cathode slurry pH and immersion time on corrosion of aluminum current collector in lithium‐ion batteries

Corrosion of aluminum can occur during the manufacturing of lithium‐ion batteries when using aqueous‐based cathode slurries. In exposure tests, the alkaline pH value of aqueous‐based cathode slurries and immersing time were revealed as the principle factors that control the corrosion of aluminum during the cathode manufacturing process. The nickel manganese cobalt oxide active material used in the slurry does not have a direct impact on corrosion of the aluminum current collector. The initiation and evolution of localized corrosion on aluminum are closely related to the formation of galvanic cells between aluminum matrix and intermetallic particles. X‐ray photoelectron spectroscopy results confirmed that the pH of cathode slurry was the only factor that alters aluminum surface composition, during which the oxide passive film was gradually degraded into hydroxide. Electrochemical characterizations showed that aluminum electrodes gave remarkably different response to the different pH of test solutions. The time‐pH‐variant electrochemical response was ascribed to the change of passive film and electric double layer properties.

Li, S. Y.↗
DOE OSTI2019

Corrosion Investigation of Zinc–Aluminum Alloy (ZA-27) Matrix Reinforced with In Situ Synthesized Titanium Carbide Particle Composites

ZA-27 alloy matrix composites comprised of different volume fractions of TiC particles as reinforcement phase were synthesized by in situ technique. Microstructural, hardness and electrochemical analysis were performed on these samples along with the base ZA-27 alloy to assess any beneficial effect of making the composites over the base alloy. It was observed that hardness increases in composites as compared to the base alloy. However, hardness of the composite reduces on increasing the reinforcement percentage. Corrosion behavior was investigated by using Tafel and EIS plots in 3.5 wt.% NaCl solution at room temperature for all the samples. The results showed increase in corrosion resistance for composites than that of base alloy. However, ZA27 + 5%TiC composite showed better results as compared to that of ZA27 + 10%TiC composite. The decreased property of ZA27 + 10%TiC composite is because of the agglomeration of particles and also by the formation of galvanic cell.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Carbon Nanotube Concentration on the Corrosion Behavior of Electroless Ni-B-CNT Coating

In this study, Ni-B-CNT composite was deposited on AISI 4140 steel using different concentrations of CNTs ranging from 0.2 to 1 gr/lit in an electroless bath. The phase analysis and surface morphology of the samples were characterized using x-ray diffraction and FESEM. The corrosion behavior of the coated samples was investigated in a 3.5 wt.% NaCl solution through potentiodynamic polarization, EIS, and electrochemical noise (EN) analyses. The corroded surface of the samples was further analyzed via FESEM observation after 10 days of immersion in corrosive medium. It was found that although adding 0.2 gr/lit CNT in electroless solution improves corrosion resistance, increasing CNT concentration from 0.2 up to 1 gr/lit increases the corrosion rate. The FESEM observations and EN results imply that the formation of micro-galvanic cells in samples with high concentration of CNTs leads to nucleation and growth of the pits. The results revealed that no passive layer was formed on the surface of the Ni-B sample, and the corrosion occurred through ionic diffusion into the cracks and crevices. The results of potentiodynamic test show that adding CNTs into electroless bath facilitates the formation of passive layer. However, results of EN test imply that increasing CNT concentration causes repetitive breakdown and recovery of passive film.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Manipulating the Second Coordination Shell of Single-Atom Fe for Enhanced Fenton Reaction

While current methods use oxidizable metals as electron donors to effectively reduce Fe 3+ , they suffer from the irreversible oxidation of these metals, ultimately compromising the catalyst’s longevity. To address this challenge, we engineered the second coordination shell of a single-atom Fe center by doping boron (B) onto a graphene-based support (Fe 1 /B-graphene) and utilized H 2 O 2 as the electron source for efficient Fe 2+ regeneration. Experimental results, supported by theoretical calculations, revealed that the Fe–O–B motif functions like a micro galvanic cell, with intermediary O atoms facilitating electron transfer between electrodes. Specifically, electrons consumed during H 2 O 2 activation at Fe 1 sites (positive electrode) are replenished by electrons extracted from H 2 O 2 at B atoms (negative electrode), where the activation energy for H 2 O 2 oxidation is significantly lower than that at Fe 1 sites. This study offers inspirational insights into the design of Fenton catalysts through precise regulation of the second coordination shell, demonstrating the potential of tailoring the outer coordination environment of single-atom catalysts to enhance catalytic performance across various reactions.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Development of MOSCATO: A CFD-Level Electrochemistry and Corrosion Simulator for Molten Salt Systems

For both coolant and fueled variants of molten salt reactors (MSRs), the corrosion of structural materials is a significant challenge. The corrosion stems from chemical and electrochemical reactions initiated by fissile material, fission products, and impurities in the salt. Lower-fidelity models rely on empirical correlations for mass transfer, simplified lumped temperature profiles, and similar assumptions. They do not capture detailed spatial variations in complex geometries, creating the need for high-fidelity modeling to bridge this gap.As we approach the demonstration and possible deployment of MSRs in this decade, the development of a high-fidelity, high-performance simulator becomes imperative. To simulate the complex electrochemical environment and corrosion within molten salt systems, we have developed the Molten Salt Chemistry And TranspOrt (MOSCATO) code. This endeavor is comprised of three essential components. First, mass transfer equations are coupled with the Navier-Stokes equations in order to account for the transport of species in the salt. Second, the diffusion of alloy constituents, such as Cr, Fe, Ni, etc. is simulated within the structural metals. Third, the alloy and salt domains are coupled to account for the heterogeneous chemical and electrochemical reactions that occur at the salt-alloy interface.MOSCATO manages all three components within the framework of the highly scalable, open-source spectral element method computational fluid dynamics code Nek5000/NekRS. This integration enables MOSCATO to harness the immense computational power of modern high-performance computing resources, ensuring both high fidelity and computational speed.In addition to code development, we have initiated a comprehensive verification and validation campaign, utilizing data from diverse sources. First, MOSCATO's electrochemical solver was verified with reference numerical data. Then validation occurred against experiments: one of a thermal galvanic cell and the other for corrosion in flowing molten salt of FLiNaK (LiF-NaF-KF). This campaign verified and validated MOSCATO as a reliable tool for simulating electrochemical environments and corrosion in molten salt systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

A General Overview of Cathodic Protection in Reinforced Concrete

Corrosion of reinforcement steel in concrete is a prevalent issue in infrastructures worldwide, with the direct costs of repair estimated to be $1 trillion annually. Treatment options are complicated by the concrete’s role in the corrosion process. Ordinary, modern-day cement is so alkaline that it maintains a thick passive layer on the steel surface, reducing corrosion to inconsequential rates. However, environmental contaminants in the form of carbon dioxide or chlorides may cause a breakdown in the passive layer, exposing the steel surface to corrosion. Galvanic cells will be free to form due to potential differences along the rebar, and anode sites will create dissolved iron ions that cannot travel far through the still concrete. Thus, rust products will accumulate directly onto the steel/concrete interface. Iron oxides have a much higher volume relative to steel, and even a miniscule amount of rust can produce enough volumetric stress to cause cracking, spalling and delamination of the surrounding concrete, increasing the risk of structural failure. Safeguards and inhibiting technology exist to limit the chances of corrosion initiation by either species, but cracking of the concrete cover and gradual accumulation of contaminants means that corrosion is unavoidable in certain environments and will initiate, given enough time.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Improved Efficiency and Stability of Pb/Sn Binary Perovskite Solar Cells Fabricated by Galvanic Displacement Reaction

In this work, a simple and generally applicable method of fabricating efficient and stable Pb-Sn binary perovskite solar cells (PVSCs) based on a galvanic displacement reaction (GDR) is demonstrated. Different from the commonly used conventional approaches to form perovskite precursor solutions by mixing metal halides and organic halides such as PbI 2 , SnI 2 , MAI, FAI, etc., together, the precursor solutions are formulated by reacting pure Pb-based perovskite precursor solutions with fine Sn metal powders. After the ratios between Pb and Sn are optimized, high PCEs of 15.85% and 18.21% can be achieved for MAPb 0.4 Sn 0.6 I 3 and (FAPb 0.6 Sn 0.4 I 3 ) 0.85 (MAPb 0.6 Sn 0.4 Br 3 ) 0.15 based PVSCs, which are the highest PCEs among all values reported to date for Pb-Sn binary PVSCs. Moreover, the GDR perovskite-based PVSCs exhibit significantly improved ambient and thermal stability with encapsulation, which can retain more than 90% of their initial PCEs after being stored in ambient (relative humidity (RH) ≈50%) for 1000 h or being thermal annealed at 80 °C for more than 120 h in ambient conditions. These results demonstrate the advantage of using GDR to prepare tunable bandgap binary perovskites for devices with greatly improved performance and stability.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The Effect of Annealing Time on Microstructure and AC Corrosion Behavior of X80 Steel in Simulated Solution of Alkaline Soil

The alternating current (AC) corrosion behavior of X80 steels annealed for different times was investigated in an alkaline soil simulation solution by electrochemical measurement, immersion test and surface analysis technology. The results show that with or without AC interference, the steels annealed for various times have different corrosion resistance. The anticorrosion resistance of steel improves with an increase in annealing time. AC interference results in the evolution of the main cathodic reaction, and facilitates the corrosion of the steels. The steel annealed for 20 min presents a more severe corrosion degree with distinct pits. The corrosion behavior of the steels annealed for different times with AC application is closely related to the microstructure. A decrease in pearlite reduces the number of galvanic corrosion cells, decreasing the corrosion rate of steel. And the grain increase is beneficial for improving the corrosion resistance of the annealed steel.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Oxidation of platinum nickel nanowires to improve durability of oxygen-reducing electrocatalysts

In this study, the impact of heat treating platinum-coated nickel (Pt-Ni) nanowires in oxygen is examined to determine the effect on oxygen reduction (ORR) activity and durability. Pt-Ni nanowires exhibit promising ORR mass activities (3 times greater than Pt nanoparticles, 1.5 times greater than U.S. Department of Energy target) both before and after potential cycling for all but the highest annealing temperatures explored. The annealing of Pt-Ni nanowires in oxygen with increasing temperature is found to reduce surface area and ORR activity in comparison to the untreated material, but also reduces activity losses following durability testing. Following potential cycling, unannealed Pt-Ni nanowires show significant losses in surface area (23%) and specific activity (18%) while Pt-Ni nanowires annealed at 200°C show modest increases in surface area (2%) and specific activity (6%) after potential cycling. Increasing annealing temperatures also show a clear trend of decreasing Ni dissolution rates. While oxygen annealing has shown the ability to improve durability of Pt-Ni nanowires, significant Ni dissolution was observed in all samples and suggests oxide passivation while showing promise for improved durability, when employed by itself is insufficient to prevent all contamination concerns involving Ni dissolution.

14 SOLAR ENERGY↗
DOE OSTI2019

Non-Aqueous Electrochemical Fluorination of Used Nuclear Fuel as an Advanced Separation Process

Development of efficient and environmentally benign methods to reprocess used nuclear fuel (UNF) will enable technologies for a nuclear renaissance. Electrochemical and fluorination methods for reprocessing UNF have been proposed, but combinations of electrochemical and fluorination methods have not been investigated. Electrochemical fluorination may reduce waste volumes compared to the main large-scale aqueous methods for processing used nuclear fuel. A non-aqueous electrochemical fluorination reprocessing method has been developed and demonstrated that enables gas phase uranium recovery while allowing for potential control of the reaction using a single process. Thermodynamic modeling showed a galvanic reaction between UNF and a fluorinating agent, such as NF 3 , in a molten fluoride electrolyte was possible and could selectively fluorinate U to UF 6 . To verify the model results, a reactor system for electrochemical fluorination was constructed along with vessels for product collection and analysis. Initial trials of the electrochemical reaction were performed and characterized by several electrochemical methods. The electrochemical oxidation of U using NF 3 as an oxidizing agent was demonstrated and UF 6 as a reaction product was detected.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Atomic layer deposited aluminum nitride for interface protection of lithium germanium thiophosphate solid electrolytes

Lithium germanium thiophosphate (LGPS) is an attractive solid-state electrolyte material due to its exceptionally high ionic conductivity (~1.2 × 10 –2 S cm –1 ), comparable to many organic liquid electrolytes commonly used in batteries. Despite the high conductivity of LGPS, the susceptibility of LGPS to deleterious degradation reactions has impeded its commercial adoption into solid-state batteries. In particular, the poor voltage stability of LGPS with high-voltage cathode or lithium metal potentials often results in dramatically increasing cell impedance during galvanic cycling. Here, we use aluminum nitride (AlN) as a protection layer for Li metal anode, applied directly to the LGPS at 250 °C using plasma-enhanced atomic layer deposition, to enhance cell performance by preventing LGPS-Li metal reactions. We compare the surface chemistry and electrochemical cycling performance of atomic layer-deposited AlN grown using both plasma N 2 and NH 3 precursors. Galvanostatic cycling and electrochemical impedance spectroscopy show that AlN-coated LGPS cells perform better than bare LGPS cells in contact with Li metal anodes, with the AlN able to improve cycling longevity by over a factor of 3 in certain cases. Finally, we utilize x-ray photoelectron spectroscopy (XPS) line scans to highlight the slow room-temperature reactivity between AlN and evaporated lithium metal, and a computational model is built to aid further XPS analysis.

25 ENERGY STORAGE↗
DOE OSTI2020

Non-galvanic mass transport in molten fluoride salt isothermal corrosion cells

Mass transport of corrosion products between Ni-201 test samples and 316 L capsules in a 500-hour FLiNaK corrosion experiment has been investigated. In one experiment, the capsule and samples were electrically connected for galvanic coupling, while in the other they were electrically isolated using boron-nitride. Post-corrosion characterization of Ni-201 from the two experiments did not reveal any remarkable differences. Substantial transport of Fe and Cr from the 316 L to the Ni-201 via the salt was observed, with notable diffusion of these elements in the near-surface regions of the Ni-201 samples, while a Cr-rich film was also observed on their surfaces.

36 MATERIALS SCIENCE↗