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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

First results on the search for chameleons with the KWISP detector at CAST

We report on a first measurement with a sensitive opto-mechanical force sensor designed for the direct detection of coupling of real chameleons to matter. These dark energy candidates could be produced in the Sun and stream unimpeded to Earth. The KWISP detector installed on the CAST axion search experiment at CERN looks for tiny displacements of a thin membrane caused by the mechanical effect of solar chameleons. The displacements are detected by a Michelson interferometer with a homodyne readout scheme. The sensor benefits from the focusing action of the ABRIXAS X-ray telescope installed at CAST, which increases the chameleon flux on the membrane. A mechanical chopper placed between the telescope output and the detector modulates the incoming chameleon stream. We present the results of the solar chameleon measurements taken at CAST in July 2017, setting an upper bound on the force acting on the membrane of 80 pN at 95% confidence level. The detector is sensitive for direct coupling to matter 10 4 ≤ β m ≤ 10 8 , where the coupling to photons is locally bound to β γ ≤ 10 11 .

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Effects of Thermal Aging on the Fracture Toughness of Cast Stainless Steel CF8

Cast stainless steels are widely used in the primary coolant systems of nuclear power plants because of their high strength, toughness, and corrosion resistance. Mechanical property degradation in the steels, primarily due to a thermally-embrittled ferrite, is of major concern in an extended-term operation. To investigate the aging-induced loss of fracture resistance in cast stainless steels, static fracture resistance (J-R) testing was performed for three different CF8 cast stainless steels with significantly different d-ferrite contents. The materials were thermally-aged at 290-400°C for up to 10kh and fracture-tested at 25-400°C. It was found that the fracture toughness in high-ferrite materials generally decreased with thermal aging while the relationship between aging and fracture toughness in low-ferrite materials was rather complicated, showing non-monotonic variation with the degree of aging. While significant degradation was observed for the highly-aged high-ferrite materials, no material was observed having a K0.2mm less than 100 MPavm.

Collins, David A.↗
DOE OSTI2016

Structure and mechanical properties of improved cast stainless steels for nuclear applications

Casting of stainless steels is a promising and cost saving way of directly producing large and complex structures, such a shield modules or divertors for the ITER. Here, a series of modified high-nitrogen cast steels has been developed and characterized. The steels, based on the cast equivalent of 316 composition, have increased N (0.14-0.36%) and Mn (2-5.1%) content; copper was added to one of the heats. Mechanical tests were conducted with non-irradiated and neutron irradiated specimens at 0.7 dpa. It was established that alloying by nitrogen significantly improves the yield stress of non-irradiated steels and the deformation hardening rate. Manganese tended to decrease yield stress, but increased radiation hardening. Furthermore, the role of copper on mechanical properties was negligibly small. Analysis of structure was conducted using SEM-EDS and the nature and compositions of the second phases and inclusions were analyzed in detail. We show that the modified steels, compared to reference material, exhibit significantly reduced elemental inhomogeneity and second phase formation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Superior electrochemical performance and reduced heat generation in 3D printed vs. 2D tape-casted NMC622 electrodes

This study compares the charge storage mechanisms, thermodynamics behavior, ion transport, and heat generation in NMC622 electrodes fabricated using a novel 3D printing process and the conventional 2D tape casting process. First, potentiometric entropy measurements revealed that the charge storage mechanisms for both types of electrodes consisted of lithium deintercalation in a homogeneous solid solution of NMC622 followed by a transition from a hexagonal (H1) phase to another hexagonal (H2) phase through a monoclinic (M) phase. Both types of electrodes had similar thermodynamics behavior with overlapping entropic potential profiles. Furthermore, operando isothermal calorimetry at high C-rates indicated that the 3D printed electrodes featured larger specific capacity and better rate performance than the 2D tape-casted electrodes. The better performance of 3D printed electrodes was attributed to their larger electrode/electrolyte interfacial surface area and electrical conductivity as well as their faster lithium ion transport. As a result, the instantaneous heat generation rates were smaller in 3D printed electrodes than in 2D tape-casted electrodes, thus resulting in lower overall specific electrical energy and thermal energy dissipation per unit charge stored. Overall, additive manufacturing techniques offer great potential in producing electrodes with superior electrochemical performance and reduced heat generation for fast charging batteries.

25 ENERGY STORAGE↗
DOE OSTI2015

Grain refinement of cast zinc through magnesium inoculation: Characterisation and mechanism

It was previously found that peritectic-forming solutes are more favourable for the grain refinement of cast Al alloys than eutectic-forming solutes. In this work, we report that the eutectic-forming solute, Mg, can also significantly grain refine cast Zn. Differential thermal analysis (DTA) of a Zn–Mg alloy, in which efficient grain refinement occurred, evidenced an unexpected peak that appeared before the nucleation of η-Zn grains on the DTA spectrum. Based on extensive examination using X-ray diffraction, high resolution SEM and EDS, it was found that: (a) some faceted Zn–Mg intermetallic particles were reproducibly observed; (b) the particles were located at or near grain centres; (c) the atomic ratio of Mg to Zn in the intermetallic compound was determined to be around 1/2. Using tilting selected area diffraction (SAD) and convergent beam Kikuchi line diffraction pattern (CBKLDP) techniques, these faceted particles were identified as MgZn{sub 2} and an orientation relationship between such grain-centred MgZn{sub 2} particles and the η-Zn matrix was determined. Hence, the unexpected peak on the DTA spectrum is believed to correspond to the formation of MgZn{sub 2} particles, which act as effective heterogeneous nucleation sites in the alloy. Together with the effect of Mg solute on restricting grain growth, such heterogeneous nucleation is cooperatively responsible for the grain size reduction in Zn–Mg alloys. - Highlights: • A new eutectic-based grain refiner for the cast Zn was found. • The formation process of an intermetallic compound (MgZn{sub 2}) was characterised. • MgZn{sub 2} can act as potent heterogeneous nucleation sites above the liquidus. • A new OR between MgZn{sub 2} and η-Zn was determined using the CBKLDP technique.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Analyzing the microstructural evolution and hardening response of an Al-Si-Mg casting alloy with Cr addition

Highlights: • The formation of β-Al{sub 5}FeSi intermetallics was suppressed since impurity Fe has been consumed by Al{sub 13}Cr{sub 4}Si{sub 4} intermetallics; • A large number of Al{sub 13}Cr{sub 4}Si{sub 4} dispersoids were observed in Al dendrites in the as-quenched and aged alloy; • The precipitation of Cr-bearing dispersoids harden the as-quenched alloy by over 10HV; • The current thermodynamic database underestimate the solubility of Fe in Al{sub 13}Cr{sub 4}Si{sub 4} intermetallics during solidification simulation. - Abstract: Chromium is added to Al-Si based casting alloys for the mitigation of die soldering. In the present work, EBSD, EDS and TEM characterizations are combined with thermodynamic simulations to study the microstructural evolution and hardening response of an Al-Si-Mg-Cr casting alloy during heat treatments. It is shown that the Fe-containing intermetallic compounds formed in the inter-dendritic region were acicular π-Al{sub 8}(Fe, Cr)Mg{sub 3}Si{sub 6} phase and polyhedral Al-(Cr, Fe)-Si phase which is structurally similar to face-centered cubic Al{sub 13}Cr{sub 4}Si{sub 4}. The polyhedral Al-(Cr, Fe)-Si intermetallics that crystallized prior to β-Al{sub 5}FeSi consumed impurity Fe, suppressing the formation of β phase during gravity die casting process. Also, Cr-addition enables the precipitation of nano-scale Cr-bearing dispersoids in Al dendrite during solution treatment at 813 K. Hardness increment of over 10 HV can be induced by the Cr-bearing dispersoids for as-quenched alloy. Though the dispersoids have a moderate hardening effect on the as-quenched alloy, they may impair the ageing hardening response by acting as heterogeneous nucleation sites for coarse Mg-Si rods and Si particles when quenching into water at 338 K.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Search for Dark Matter Axions with CAST-CAPP

The CAST-CAPP axion haloscope, operating at CERN inside the CAST dipole magnet, has searched for axions in the 19.74 μeV to 22.47 μeV mass range. The detection concept follows the Sikivie haloscope principle, where Dark Matter axions convert into photons within a resonator immersed in a magnetic field. The CAST-CAPP resonator is an array of four individual rectangular cavities inserted in a strong dipole magnet, phase-matched to maximize the detection sensitivity. Here we report on the data acquired for 4124 h from 2019 to 2021. Each cavity is equipped with a fast frequency tuning mechanism of 10 MHz/ min between 4.774 GHz and 5.434 GHz. In the present work, we exclude axion-photon couplings for virialized galactic axions down to g aγγ = 8 × 10 –14 GeV –1 at the 90% confidence level. The here implemented phase-matching technique also allows for future large-scale upgrades.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Corrosion evaluation of Al-Cu-Mn-Zr cast alloys in 3.5% NaCl solution

Corrosion behavior of cast Al-Cu-Mn-Zr (ACMZ) and RR350 alloys was compared to a cast 319 alloy in 3.5 wt.% NaCl. After 168 h immersion, ACMZ and RR350 alloys suffered from preferential attack adjacent to intermetallic particles decorated at grain boundaries while the attack in 319 occurred in eutectic Al-Si dendritic boundaries. Electrochemical data allowed semiquantitative comparison of alloy resistance to corrosion initiation, and ACMZ type alloys, including RR350 and three alloys with higher Cu, were considered more resistant than 319 due to the absence of deleterious Si particles. In case of 319, such Si particles presumably drove higher micro-galvanic influence to initiate and sustain Al corrosion. With lower susceptibility to corrosion initiation, ACMZ alloys should exhibit higher or at minimum similar resistance compared to cast 319.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Importance of microstructural features in mechanical response of cast-cured HMX formulations

We report that cast-cure formulations of plastic-bonded explosives (PBX) present some advantages in manufacturing and application compared to traditional pressed slurry formulated materials. For example, these formulations can be cast to specific shapes and then cured in place, avoiding the need for machining precision parts. However, the microstructure of these materials can be greatly affected by the specific manufacturing process. Here, we evaluate the effect of minor changes to the formulation and manufacturing process on several cyclotetramethylene-tetranitramine (HMX) PBXs. The binders were based on hydroxyl-terminated polybutadiene (HTPB) and cast-cured using diphenylmethane diisocyanate (isonate) as a curing agent. We examined the materials using X-ray computed tomography (CT) imaging and uniaxial compression testing. The isonate content was found to significantly affect the modulus and strength of the binder. The presence of significant void content could be controlled by adding a centrifuging step during the curing process, but the resulting effect on mechanical properties was relatively minor. Finally, mesoscale simulations showed that differences in the mechanical strength of the binder were not sufficient to describe the differences observed in mechanical testing, indicating that the HMX-binder adhesion was also being changed by the manufacturing process.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Microstructural stability and mechanical properties of the as-cast and heat-treated newly developed TiNbCrTa refractory complex concentrated alloy

In this study, a TiNbCrTa refractory complex concentrated alloy (RCCA) was prepared using vacuum arc remelting. The microstructural evolution and mechanical properties of both as-cast and heat-treated RCCA samples were analyzed. Heat treatment (HT) was performed at 800–1200 °C for 1 h in a vacuum-sealed environment. These samples exhibited a formation of Cr 2 Nb and Cr 2 Ti Laves phases. A variation in elemental distribution was observed, with interdendritic (ID) regions showing higher fractions of Ti and Cr, while the dendritic regions had a greater concentration of Ta and Nb. Micro-segregation at the IDs was confirmed through energy dispersive x-ray spectroscopy mapping, which inferred the formation of Cr- and Ti-rich phases during HT at 800–1200 °C. High-temperature HT at 1200 °C for 1 h led to the evolution of the hcp omega phase. Prolonged HT at 1200 °C for 96 h resulted in the evolution of a Cr-rich Laves phase (Cr 2 Ta), which was homogeneously distributed within the microstructure, indicating an unstable microstructure. Furthermore, despite prolonged HT, a variation in the elemental distribution persisted due to the presence of dendritic and ID regions. Electron backscattered diffraction analysis revealed the presence of bcc and hcp phases in the dendritic and ID regions, respectively, of the as-cast and HTed samples. The as-cast samples demonstrated a high compressive strength of approximately 2 GPa. Micro-hardness values increased with the HT temperature up to 1000 °C. Further increases under HT conditions did not significantly reduce the microhardness value, whereas prolonged HT at 1200 °C led to an increase in the microhardness value. Overall, the newly developed TiNbCrTa RCCA exhibited high-strength behavior even after the phase transformation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

The pathfinder X-Ray axion telescope for the International Axion Observatory (IAXO) and axion searches at the CERN Axion Solar Telescope (CAST)

The axion, a hypothetical pseudo-scalar particle proposed by Peccei and Quinn to resolve the strong CP problem in quantum chromodynamics, remains one of the most compelling dark matter candidates. Axions and Axion-Like Particles (ALPs) are characterized by a broad and largely unconstrained parameter space in mass and coupling strength, motivating extensive experimental searches. The International Axion Observatory (IAXO) is a next-generation axion helioscope designed to achieve over an order of magnitude improvement in sensitivity to the axion-photon coupling constant gaγ relative to previous experiments such as the CERN Axion Solar Telescope (CAST). IAXO will employ large-scale superconducting magnets, precision x-ray optics, and ultra-low-background detectors to search for solar axions produced primarily via the Primakoff effect. This work presents the design and performance of the IAXO pathfinder x-ray optic, a technological demonstrator that validated the optical concepts for IAXO through axion searches at CAST. Comprehensive ray-tracing simulations and experimental measurements were conducted to assess the optic's effective area, detection efficiency, and background suppression capabilities. Deployed at CAST in conjunction with Micromegas and GridPix detectors, the Pathfinder demonstrated record-setting sensitivity to both gaγ and the axion-electron coupling gae, establishing the most stringent laboratory constraints on solar axions to date. These results confirm the viability of the IAXO optical design and detector concept, providing a critical technological benchmark that informs the ongoing development of the BabyIAXO and full-scale IAXO telescopes.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Comparison of dielectric properties of additively manufactured vs. solvent cast polyimide dielectrics

The permittivity, dielectric loss, and DC dielectric breakdown strength of additively manufactured, solvent-cast, and commercial polyimide films are reported As expected, commercial films performed better than both AM and solvent-cast lab-made films. Solvent-cast films generally performed better than AM films, although performance depended on the optimization of the material for the specific deposition technique. The most significant degradation of performance in all the lab-made films was in the dispersion of both the x/Df measurements and the dielectric breakdown strength (Weibull β). Commercial films had a breakdown strength of 4891 kV/cm and β = 13.0 whereas the highest performing lab-made films had a breakdown strength of 4072 kV/cm and β = 3.8. Furthermore, this increase in dispersion in all the lab-made samples is attributed to higher variability in the preparation, a higher defect level related to fabrication in the lab environment and, for some AM samples, to morphology/topology features resulting from the deposition technique.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Engineering scale demonstration of a prospective Cast Stone process

This report documents an engineering-scale demonstration with non-radioactive simulants that was performed at SRNL using the Scaled Continuous Processing Facility (SCPF) to fill an 8.5 ft container with simulated Cast Stone grout. The Cast Stone formulation was chosen from the previous screening tests. Legacy salt solution from previous Hanford salt waste testing was adjusted to correspond to the average composition generated from the Hanford Tank Waste Operation Simulator (HTWOS). The dry blend materials, ordinary portland cement (OPC), Class F fly ash, and ground granulated blast furnace slag (GGBFS or BFS), were obtained from Lafarge North America in Pasco, WA. Over three days, the SCPF was used to fill a 1600 gallon container, staged outside the facility, with simulated Cast Stone grout. The container, staged outside the building approximately 60 ft from the SCPF, was instrumented with x-, y-, and z-axis thermocouples to monitor curing temperature. The container was also fitted with two formed core sampling vials. For the operation, the targeted grout production rate was 1.5 gpm. This required a salt solution flow rate of approximately 1 gpm and a premix feed rate of approximately 580 lb/h. During the final day of operation, the dry feed rate was increased to evaluate the ability of the system to handle increased throughput. Although non-steady state operational periods created free surface liquids, no bleed water was observed either before or after operations. The final surface slope at a fill height of 39.5 inches was 1-1.5 inches across the 8.5 foot diameter container, highest at the final fill point and lowest diametrically opposed to the fill point. During processing, grout was collected in cylindrical containers from both the mixer discharge and the discharge into the container. These samples were stored in a humid environment either in a closed box proximal to the container or inside the laboratory. Additional samples collected at these sampling points were analyzed for rheological properties and density. Both the rheological properties (plastic viscosity and yield strength) and density were consistent with previous and later SCPF runs.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Fan Fuel Casting Final Report

LANL was approached to provide material and design guidance for a fan-shaped fuel element. A total of at least three castings were planned. The first casting is a simple billet mold to be made from high carbon DU-10Mo charge material. The second and third castings are for optimization of the actual fuel plate mold. The experimental scope for optimization is only broad enough for a second iteration of the mold design. It is important to note that partway through FY17, this project was cancelled by the sponsor. This report is being written in order to capture the knowledge gained should this project resume at a later date.

42 ENGINEERING↗
DOE OSTI2018

Prototyping and Manufacturing of Magnetic Gearbox Components using Innovations in Castings

This project combines additive manufacturing with the broadly deployed practice of metal casting. Combining these methods will unlock new design possibilities while reducing the economic burden of early stage prototyping while leveraging well established high throughput sand casting. Two main approaches are evaluated: direct printing of single use sand molds and printing of reusable impression patterns used to create sand molds. Reusable impression molds typically can be used to produce hundreds to several thousands of casting thereby amplifying the function of the 3D printed replica mold. Emrgy’s newly developed and tested proprietary magnetic gearbox system for low head hydroelectricity generation was the subject part of this study. Leveraging ORNL’s additive manufacturing capability and expertise, a pattern impression was produced and used to create multiple sand molds of the gearbox during phase 1. Even before considering the cost savings possible once rigging and pattern mounting is optimized through repetition and improved design, final part costs using this combined method resulted in an 80% cost reduction over EMRGY’s previous method of subtractive manufacturing for gearbox production.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Off-Gas Condensate and Cast Stone Analysis Results

A sample of off-gas condensate produced during a demonstration test of the direct-feed low-activity waste (DFLAW) Radioactive Waste Test Platform using waste retrieved from Hanford storage tank AP-105 waste was analyzed for major cations, anions, total cyanide, Resource Conservation and Recovery Act (RCRA) metals, selected radionuclides, and selected organic compounds. The remaining off-gas condensate was concentrated through evaporation and then used to produce Cast Stone waste forms. After the solid waste forms cured for 28 days, U.S. Environmental Protection Agency (EPA) Method 1311 (EPA 1992) Toxicity Characteristic Leach Procedure (TCLP) tests were conducted on two samples. The TCLP leachates were analyzed for RCRA metals, fluoride, and total cyanide. These chemical analyses were conducted to collect data on the waste form performance and to determine if the waste form will meet the disposal requirements of the Waste Control Specialists LLC (WCS) Federal Waste Disposal Facility (FWF) in Texas (WCS 2015) and the Integrated Disposal Facility at Hanford. The radionuclide results in the off-gas condensate were used to estimate concentrations in the Cast Stone waste forms; these estimates were then compared to Class C limits (30 TAC 336.362 Appendix E). With the possible exception of U-232, all measured radionuclides were determined to be below their respective Class C limits. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to measure most of the radionuclides. It is not possible to differentiate the isotope measured at mass 232 between U 232 and Th-232 by mass spectroscopy. Class C limit comparisons were made by assuming two maximum possible scenarios; one in which all the isotope at mass 232 occurred as Th-232, and another assigning the entire mass contribution to U-232. If the isotope at mass 232 is all Th-232 then the waste form is well below its Class C limit; however, if the isotope at mass 232 is all U-232, then the Class C limit would be exceeded by more than a factor of 8. A chemical procedure to separate uranium from thorium followed by reanalysis by ICP-MS would be required to resolve this issue. A similar issue occurs at mass 238, which could be U-238 or Pu-238; however, in this case Pu-238 can be ruled out as a contributor to the isotope measured at mass 238 for the following reasons. Pu-238 has a half-life of 87.7 years and its daughter product (U-234) has a half-life of 2.5 × 105 years and a measured concentration of < 0.002 µg/L. If significant concentrations of Pu-238 were present in this waste, then the amount of measurable U 234 would have increased over the decades of storage in the Hanford tanks. Because this was not observed, it is concluded that the isotope measured at mass 238 is all U-238. A total of 68 organic compounds were targeted for analysis in the off-gas condensate. Of these compounds, only nine were measured above their respective minimum reportable concentration. These compounds were acenaphthene, acetone, n-butyl alcohol, p,p’-DDT, methyl ethyl ketone, nitrobenzene, o nitrophenol, pyridine, and toluene. Of the detectable compounds, only acenaphthene, acetone, o nitrophenol, and pyridine were above wastewater standards (40 CFR 268.48 - Universal Treatment Standards). None of the organic compounds exceeded the non-wastewater standards (40 CFR 268.48 - Universal Treatment Standards). Analysis of the TCLP leachates from the Cast Stone waste forms indicated that none of the analytes exceeded the Universal Treatment Standard and, in general, all were well below the standards.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Secondary Phase Objects in As-cast U-10 wt% Zr

U-10Zr castings have shown secondary phase objects when the as-cast material was examined using optical metallography and/or scanning electron microscopy. Attempts to identify these objects indicated they were rich in zirconium, but not in uranium. Exams of other U-10Zr castings in the past had indicated that these were likely Zr-carbides. Because of potential interferences in EDS spectra for carbon and uranium,a more detailed examination is necessary.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Castings and Processing of Uranium and Uranium Alloys

Presentation Outline: Production of DU Derby; DU Casting and Processing; Vacuum Induction Melting (VIM); Cast DU Microstructure / U-C(-N) Phase Diagram; Wrought DU; DU Hydro Plate and DU Specifications; Enriched Uranium; Wrought U-6Nb; Vacuum Arc-Remelting (VAR); U-6Nb Ingot Production (and Variations); Wrought Processing; U-Nb Macrostructure; Direct Cast U-6Nb; Plasma Arc Melting (PAM)

36 MATERIALS SCIENCE↗