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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Aluminum Metal–Organic Framework Triggers Carbon Dioxide Reduction Activity

Confinement of metal centers is a powerful tool to manipulate reactivity and tune selectivity in chemical transformations. While aluminum as a foil is inactive for carbon dioxide reduction and shows high selectivity for the hydrogen evolution reaction, here we show that aluminum confined in a metal-organic framework (MOF), MIL-53(Al), suppresses hydrogen evolution reaction activity and enhances carbon dioxide reduction. This aluminum MOF can produce up to 40% faradaic efficiency for carbon monoxide and formic acid. Here, this study demonstrates that the unique reaction environment created by the MOF enables changes in reaction selectivity and can impart atypical catalytic capabilities to metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Integrated Circular Economy Model System for Direct Lithium Extraction: From Minerals to Batteries Utilizing Aluminum Hydroxide

Aluminum hydroxide, an abundant mineral found in nature, exists in four polymorphs: gibbsite, bayerite, nordstrandite, and doyleite. Among these polymorphs gibbsite, bayerite, and commercially synthesized amorphous aluminum hydroxide have been investigated as sorbent materials for lithium extraction from sulfate solutions. The amorphous form of Al(OH) 3 exhibits a reactivity higher than that of the naturally occurring crystalline polymorphs in terms of extracting Li + ions. This study employed high-temperature oxide melt solution calorimetry to explore the energetics of the sorbent polymorphs. The enthalpic stability order was measured to be gibbsite > bayerite > amorphous Al(OH) 3 . The least stable form, amorphous Al(OH) 3 , undergoes a spontaneous reaction with lithium, resulting in the formation of a stable layered double hydroxide phase. Consequently, amorphous Al(OH) 3 shows promise as a sorbent material for selectively extracting lithium from clay mineral leachate solutions. Further, this research demonstrates the selective direct extraction of Li + ions using amorphous aluminum hydroxide through a liquid–solid lithiation reaction, followed by acid-free delithiation and relithiation processes, achieving an extraction efficiency of 86%, and the maximum capacity was 37.86 mg·g –1 in a single step during lithiation. With high selectivity during lithiation and nearly complete recoverability of the sorbent material during delithiation, this method presents a circular economy model. Furthermore, a life cycle analysis was conducted to illustrate the environmental advantages of replacing the conventional soda ash-based precipitation process with this method, along with a simple operational cost analysis to evaluate reagent and fuel expenses.

25 ENERGY STORAGE↗
DOE OSTI2023

Review and Summary of Oxide Thickness Data for Aluminum-Clad Spent Nuclear Fuel

The U.S. Department of Energy (DOE) owns a large inventory of aluminum-clad spent nuclear fuel (ASNF) in interim storage pending ultimate disposition, with more being generated by currently operating research reactors. Dry storage in sealed DOE Standard Canisters is being investigated as an approach for long-term interim storage and/or disposition in a repository for ASNF. A primary challenge for ASNF storage is the presence of aluminum (oxy)hydroxide layers formed on the cladding surfaces during water exposure in the reactor and in wet storage, which forms a reservoir of chemisorbed water not readily removed at low (<100°C) drying temperatures. Free, physisorbed, and chemisorbed water are all susceptible to radiolytic breakdown under irradiation and can release hydrogen gas. Identifying the likely range of (oxy)hydroxide loadings on ASNF that may be placed in dry storage will help to ensure that the impact of the (oxy)hydroxide is adequately accounted for while avoiding over conservatism and enable mitigation strategies to be implemented where needed. The current report summarizes information on (oxy)hydroxide thicknesses and characteristics from the literature and from recent measurements taken in the present research campaign. In general, corrosion studies have indicated that the corrosion and oxide buildup on aluminum are affected by numerous conditions, including pH, temperature and heat flux, coolant flowrates, irradiation (in-reactor vs. unirradiated tests), duration of water exposure, and the amount of oxide already on the surface. Some of these factors are interrelated (e.g., the local temperature, heat flux, and coolant flowrate). Observations of the impact of irradiation (in-reactor versus ex-reactor measurements) on corrosion and oxide thickness are mixed, but multiple studies indicate that there is a significant difference between in-reactor and ex-reactor corrosion kinetics, even when other operating conditions such as pH, flowrate, heat flux, etc., simulate those in a reactor.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Milestone 1.2.12: The Fate of Oxygen Radical Species in Corroded Aluminum Alloys under Irradiation

The U.S. Department of Energy tasked Idaho National Laboratory to evaluate the feasibility of extended dry storage of aluminum-clad spent nuclear fuel (ASNF) in heliumbackfilled canisters. A significant research effort has been devoted to determining the amount of radiation-induced molecular hydrogen (H 2 ) generation from corrosion layers that would be present on the fuel assembly surfaces. However, limited attention has been directed to the oxygen radical species that are concurrently generated in these H 2 producing radiation environments. This report collates and summarizes the available experimental and computational studies on the fate of these reactive oxygen radicals during the irradiation of aluminum oxyhydroxide and hydroxide polymorphs typically formed on ASNF. Based on this review, it is determined that radiation-induced oxygen-centered radicals do not react to give molecular oxygen gas (O 2 ), but rather remain trapped in the aluminum corrosion layers in their original crystal lattice positions. Overall, O 2 generation will not be a concern for extended storage of ASNF in helium-backfilled canisters. That is, no O 2 contribution to pressurization of sealed dry storage systems or creation of a flammable atmosphere is anticipated.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Develop a new integrated macro→micro←nano (MMN) multiscale modeling framework to optimize high strength aluminum alloys and processes for vehicle light-weighting​

Bending tests provide a means to study plane strain fracture performance of 6000 series aluminum alloys. Metrics from bending tests have been correlated with self-pierce riveting (SPR) performance of a high strength AA6111 automotive aluminum alloy in previous works. Using the ORNL HPC resources, this project developed an innovative macro→micro←nano (MMN) multiscale microstructure-based finite element (FE) code to further understanding of the relationship between microstructure and fracture properties of high-strength 6000-series alloys. This work started with microstructural characterization in both mesoscale and nanoscale and bending performance characterization of AA6111 HS2-T6 alloy at Ford, the MMN framework was applied to this alloy to simulate 3-point VDA bending. From the results of the macro-modeling of 3-point VDA bending, the critical region of fracture was identified, and the region geometry was used to construct the micro-model. The fracture criterion of micron-scale precipitates and aluminum matrix which contains submicron and nano particles (AL-SMP-NP) in the micro-model was calibrated and validated by comparing simulated and measured bending results. With the AL-SMP-NP fracture strain obtained, the fracture strain of Al-matrix containing nano particles (ALNP) will similarly be determined by a submicron scale-model using an edge-constrained FE modeling approach developed by Hu et al. With the ALNP fracture strain obtained, the fracture strain of Al-matrix containing no particles will similarly be determined by a nano scale-model using an edge-constrained FE modeling approach. After the MMN framework is built and fracture criterion calibrated, nano-model FE simulations with virtual microstructures was performed to obtain a reduced order model (ROM) of the fracture criterion of the ALNP as a function of volume fraction, size, and distribution of the nanoparticle. This nano→submicron→micro modeling part allows exploration of the influence of different material nanostructures from different process conditions on the bending properties within the multiscale bending simulation framework and the ROM of material bendability as a function of nanoparticle size and shape was established. This obtained reduced order model (ROM) could help guide the design and selection of materials to improve existing SPR process models that could replace trial-and-error rivet/die selection and help to design new rivet/die combinations capable of robustly joining new higher strength 6000 5 series alloys in automotive body structures. This would enable lightweighting of Ford vehicles leading to greater fuel efficiency and reduce manufacturing time and energy.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Neutron tomography of porous aluminum electrodes used in electrocoagulation of groundwater

In this work, neutron computed tomography (CT) is employed to investigate the dissolution of porous aluminum electrodes during electrocoagulation (EC). Porous electrodes were chosen in efforts to reduce electric power requirements by using larger surface-area electrodes, having both inner and outer surface, for the EC process. Neutron CT allowed 3D reconstruction of the porous electrodes, and image analysis provided the volume of each electrode vs. thickness, which can indicate whether the inner surface is effectively involved in EC reactions. For the anode, the volume decreased uniformly throughout the thickness of the electrode, indicating that both the outer and inner surface participated in electrochemical dissolution, while the volume of the cathode increased uniformly vs. thickness, indicating deposition of material on both the outer and inner surface. The attenuation coefficient vs. thickness, increased for both anode and cathode, indicating surface chemistry changes. For the anode, the attenuation coefficient increased slightly but uniformly, probably due to aluminum oxide formation on the surface of the anode. For the cathode, the attenuation coefficient increased more than for the anode and nonuniformly. The higher increase in the attenuation coefficient for the cathode is due to precipitation of aluminum hydroxide on the electrode surface, which added hydrogen. Image analysis also showed that, although the attenuation coefficient increased throughout the thickness of the electrode, most of the hydroxide deposition occurred on the outer surface. Energy analysis showed that porous electrodes can be used to reduce process energy requirements by as much as 4 times compared to solid electrodes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

The Isothermal Oxidation of High-Purity Aluminum at High Temperature

The isothermal oxidation in air of high purity aluminum sheet was studied as a function of temperature using Thermogravimetric Analysis simultaneously with Differential Scanning Calorimetry (TGA/DSC). The rates and extents of oxidation were found to be non-linear functions of the temperature, in agreement with the literature. Between 650 °C and 750 °C very little oxidation took place; at 850 °C oxidation occurred after an induction period, while at 950 °C oxidation occurred without an induction period. At oxidation temperatures between 1050 °C and 1150 °C rapid passivation of the surface of the aluminum occurred, while at 1250 °C and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase in mass was accompanied by a significant exotherm, which was quantified by DSC. At temperatures of 1050 °C and above the specimen coalesced into a spheroidal particle, whereas at lower temperatures the original morphology was retained due to the cohesive strength of the native oxide layer. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases. Interrogation of the surface of an oxidized spheroidal particle by SEM showed a fractured alumina shell around a partially hollow core of aluminum which appeared to have grain boundaries.

36 MATERIALS SCIENCE↗
NASA NTRS1955

Metallography of Aluminum and Its Alloys : Use of Electrolytic Polishing

Recent methods are described for electropolishing aluminum and aluminum alloys. Numerous references are included of electrolytic micrographic investigations carried out during the period 1948 to 1952. A detailed description of a commercial electrolytic polishing unit, suitable for micrographic examination of aluminum and its alloys, is included.

MATERIALS, PROPERTIES - STRUCTURE↗
NASA NTRSDate not supplied

Influence of Evaporation Rate and Chamber Pressure on the FUV Reflectance and Physical Characteristics of Aluminum Films

Space telescopes for studying astrophysical phenomena from the far ultraviolet (FUV) to the near infrared (NIR) require durable mirror coatings with high and uniform reflectance over a very broad spectral region. While coatings for the optical and NIR region are well developed with proven performance, the FUV band presents significant challenges, particularly below 115 nm. Recent developments in physical vapor deposition (PVD) coating processes of aluminum mirrors that are protected with a metal-fluoride overcoat to prevent oxidation (such as LiF, MgF2, or AlF3) have improved reflectance in the FUV. While the emphasis in these studies has been placed on improving the deposition conditions of the metal-fluoride overcoats, less attention has been devoted to how deposition parameters (such as vacuum conditions or deposition rates) may affect the quality of the aluminum mirrors. This paper presents characterization of Al+MgF2 coupons made by flash evaporation of aluminum followed by resistive evaporation of MgF2. Samples were manufactured under a variety of processing conditions and the relationship between processing variables and mirror FUV reflectivity is analyzed. Performance characterization was based on the measured near-normal reflectance in the FUV (90-180 nm), and normal-incidence transmittance in the visible was done to analyze the possible presence of pinholes in the mirror. We demonstrated pinhole-free Al/MgF2 mirrors deposited at room temperature with a reflectivity of 0.91 at 122 nm wavelength. This reflectivity enhancement was achieved solely through parameter optimization.

FUV reflectance, aluminum, PVD, deposition rate, A↗
NASA NTRSDate not supplied

Aluminum Borohydride Ammines as Fuels for Hybrid Rocket Motors: Theoretical Performance and Particle Synthesis

The aluminum borohydride ammines, Al(BH4)3·XNH3, are a family of complexes between aluminum borohydride and ammonia for which up to six moles of ammonia can be complexed per mole of aluminum borohydride. Two of these complexes, the diammine (X = 2) and hexammine (X = 6) are of particular interest for use in hybrid rocket motors as additives and stand alone fuels. This study compares these compounds against other metal hydride for their potential as additives to increase the regression rate of solid fuel grains. The theoretical performance of the diammine as a stand alone fuel paired with non-toxic oxidizers is also investigated. The low temperature and good performance of these combinations make them of interest for low cost orbital maneuvering thrusters. Finally, the synthesis process for Al(BH4)3·6NH3 is discussed and TGA/DSC results are presented.

hybrid rockets↗
NASA NTRSDate not supplied

Aluminum borohydride ammines as fuels for hybrid rocket motors: theoretical performance and particle synthesis

The aluminum borohydride ammines, Al(BH4)3·XNH3, are a family of complexes between aluminum borohydride and ammonia for which up to six moles of ammonia can be complexed per mole of aluminum borohydride. Two of these complexes, the diammine (X = 2) and hexammine (X = 6) are of particular interest for use in hybrid rocket motors as particle additives and stand alone fuels. This study compares these compounds against other metal hydrides for their potential to increase the regression rate of solid fuel grains. The theoretical performance of the diammine as a stand alone fuel paired with non-toxic oxidizers is also investigated. The low temperature and good performance of these combinations make them of interest for low cost orbital maneuvering thrusters. Finally, results on the synthesis of Al(BH4)3·6NH3 and its thermal characterization are presented.

hybrid rockets↗
NASA NTRS1945

The Elastic Constants for Wrought Aluminum Alloys

There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys.

ALUMINUM ALLOYS, WROUGHT-ELASTICITY↗
DOE OSTI2024

First Principles Study of Aluminum Doped Polycrystalline Silicon as a Potential Anode Candidate in Li‐ion Batteries

Addressing sustainable energy storage remains crucial for transitioning to renewable sources. While Li‐ion batteries have made significant contributions, enhancing their capacity through alternative materials remains a key challenge. Micro‐sized silicon is a promising anode material due to its tenfold higher theoretical capacity compared to conventional graphite. However, its substantial volumetric expansion during cycling impedes practical application due to mechanical failure and rapid capacity fading. A novel approach is proposed to mitigate this issue by incorporating trace amounts of aluminum into the micro‐sized silicon electrode using ball milling. Density functional theory (DFT) is employed to establish a theoretical framework elucidating how grain boundary sliding, a key mechanism involved in preventing mechanical failure is facilitated by the presence of trace aluminum at grain boundaries. This, in turn, reduces stress accumulation within the material, reducing the likelihood of failure. To validate the theoretical predictions, capacity retention experiments are conducted on undoped and Al‐doped micro‐sized silicon samples. In conclusion, the results demonstrate significantly reduced capacity fading in the doped sample, corroborating the theoretical framework and showcasing the potential of aluminum doping for improved Li‐ion battery performance.

25 ENERGY STORAGE↗
DOE OSTI2024

Low‐Temperature and High‐Rate Rechargeable Aluminum Batteries Enabled by Ternary Eutectic Electrolytes

Abstract Rechargeable aluminum batteries (RABs) have garnered extensive scientific attention as a promising alternative chemistry due to the inherent advantages associated with aluminum (Al) metal anodes, including their high theoretical capacities, cost‐effectiveness, environmental friendliness, and inherent non‐flammable properties. Nonetheless, the practical energy density of RABs is constrained by the electrolytes that support lower operational voltage windows. Herein, we report a ternary eutectic electrolyte composed of 1‐ethyl‐3‐methylimidazolium chloride ([C 2 C 1 im]Cl):1‐butyl‐3‐methylimidazolium chloride ([C 4 C 1 im]Cl):aluminum chloride (AlCl 3 ) for the application of RABs. The electrolyte exhibits a high operational potential window (~3 V vs. Al/Al 3+ on SS 316) and high ionic conductivity (~8.3 mS cm −1 ) while exhibiting only a low temperature glass transition at −65 °C suitable for all‐climate conditions. Al||graphene nanoplatelets cell delivers a high capacity of ~117 mAh/g, and ~43 mAh/g at a very high current densities of 1 A/g and 5 A/g, respectively. The cells render a reversible capacity of 20 mAh/g at −20 °C and 17 mAh/g at −40 °C, indicating their suitability for operation under extreme environmental conditions. We comprehensively evaluated the design and optimization of carbon paper‐based battery systems. The ternary eutectic electrolyte demonstrates exceptional electrochemical performance, thus signifying its substantial potential for utilization in high‐performance energy storage systems in all climates.

Vadthya, Raju↗
DOE OSTI2020

The Efficacy of Replacing Metallic Cerium in Aluminum–Cerium Alloys with LREE Mischmetal

The ongoing development of aluminum–cerium alloys has produced materials exhibiting elevated temperature mechanical property retention, long term microstructural stability, and flexible processability compared to traditional aluminum alloys, accommodating the growing demand for high temperature aluminum alloys not requiring the use of high-cost elements like scandium. To date, reported Al–Ce alloy compositions contain large amounts of elemental cerium. Mischmetal (MM), a mixture of lanthanum, cerium, and other light rare earth elements (LREE) is less expensive and more available than pure cerium. The chemical similarity of the LREEs means there is possibility to use MM as the primary alloy addition, lowering alloy cost. This talk will report the effect of using MM instead of cerium in a 12 wt% binary alloy on mechanical properties, phase constituency, thermal stability, and load sharing. Results will show that MM can be substituted completely for cerium with a mostly positive impact on alloy performance.

Sims, Zachary↗
DOE OSTI2021

Anodization Compatibility of Eutectic Aluminum–Cerium Alloys

Anodizing is the most common method for producing corrosion resistant layer coatings for aluminum alloys. It is possible to use anodizing with most commercial aluminum alloys to increase material corrosion resistance, but often the brittle, passive oxide layer formed during anodization does not adhere well to the material, reducing effectiveness, and overall compatibility. Therefore, it is important for the compatibility and effect of anodization to be studied for any newly developed alloys. Recently developed eutectic Al–Ce alloys offer advantages like high castability, limited or no heat treatment requirements, and high-temperature strength retention. In this work, Al–Ce alloys are shown to have good compatibility with current processes and may exhibit improved adhesion of passivated layer because intermetallic phases anchor the anodized product to unconverted bulk. The source of these phenomena and their effect on material corrosion and layer adhesion properties of Al–Ce alloys will be discussed and compared with results from common commercial aluminum alloys.

Sims, Zachary↗
DOE OSTI2025

Simultaneously Improving Process Efficiency and Mechanical Properties in Aluminum Alloys with Applied Magnetic Fields

In the aluminum heat treatment sector, large resistive batch furnaces are used for many heat treatment processes and are generally always running, operating at approximately 20–30% efficiency. The primary avenue for energy savings lies in shortening heat treatment times, which can be 24+ hours for solutionizing (450–625 °C) and aging treatments (150–250 ℃), depending on the alloy and specification requirements. The application of high magnetic fields (<9 T) has shown to significantly reduce aluminum alloy heat treatment times, while achieving enhanced mechanical properties. Here, we explore the effects of thermomagnetic processing on the heat treatment response of a commercial aluminum alloy A390.1. Heat treatment times were reduced by >80%, while achieving ~10% improvement in microhardness, and these improvements persisted after longer thermal exposures simulating use. The microstructural evolution and resulting properties will be discussed.

Kesler, Michael [ORNL] (ORCID:0000000161423128)↗
DOE OSTI2022

Development of Aluminum Scandium Nitride Molecular Dynamics Force Fields with Scalable Multi-Objective Bayesian Optimization

Scandium (Sc)-doped aluminum nitride (AlN) exhibits improved piezoelectric properties, which is favorable for sensor applications. Although many experimental studies exist to fine tune the material properties for design purposes, an atomistic level understanding of the structure-property (S-P) relationships is needed, which is the aim of this work. Molecular dynamics can be used to understand the S-P relationships. However, the limited availability of suitable force fields has been a major challenge for accurate property predictions. In this article, a robust force field calibration method using a scalable multi-objective Bayesian optimization approach is presented. Optimizations with three, six, and eight objectives are applied to calibrate aluminum scandium nitride force fields based on the piezoelectric characteristics, modulus of elasticity, and lattice parameters at different Sc-doped levels. Furthermore, the performances of the different force fields are compared, and the performance of the higher dimensional objective problems is discussed. The highly scalable molecular dynamics force field development method is successfully implemented, resulting in the creation of several aluminum scandium nitride molecular dynamics force fields for piezoelectric applications at varying Sc dope levels.

36 MATERIALS SCIENCE↗