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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

200 MeV proton irradiation of the oxide-dispersion-strengthened copper alloy (GlidCop-Al15)

In search to identify extremely stable materials to perform the collimation function of the 7-TeV proton beam halo at the Large Hadron Collider (LHC), oxide dispersion strengthened (DS) copper alloys were explored. These internally oxidized copper alloys known as GlidCop are also leading candidates for high heat flux applications in fusion reactors and as divertor and first wall structure in ITER. These considerations have led to an extensive body of research on neutron-induced changes in the microstructure and physio-mechanical properties. This study focused primarily on the damage induced by 200 MeV protons on as wrought and cold-worked GlidCop Al15 DS copper ally selected as a candidate material of the LHC beam collimation structure to damage levels up to ~10 displacements-per-atom (dpa) and irradiation temperatures up to ~600 °C. For reference, low dose spallation neutron damage at sub-zero irradiation temperature was included in the study. Proton irradiation effects on dimensional stability, mechanical behavior, electrical resistivity and X-ray diffraction-based microstructural changes are presented in the paper. GlidCop Al15 exhibited excellent thermal stability and superior to pure Cu resistance to conductivity loss. Proton irradiation-induced hardening and embrittlement at distinct irradiation temperature regimes were shown to follow similar trends to what was reported under neutron exposure to even higher dpa damage. At T irr ~600 ± 20 °C the cold-worked DS copper alloy exhibited softening accompanied by elongation reduction while at T irr ~200 ± 10 °C the as-wrought experienced hardening with elongation increase. Furthermore, high resolution X-ray diffraction revealed that even low-dose neutron irradiation has a strong influence on the size and distribution of dispersed Al 2 O 3 particles.

36 MATERIALS SCIENCE↗
DOE OSTI2020

The use of U3Si2/Al dispersion fuel for high power research reactors

In order to investigate the irradiation performance of U3Si2/Al dispersion fuel at relatively aggressive reactor conditions, compared to how this fuel is typically used in a research or test reactor, post irradiation examination was performed on two fuel plates that were irradiated at ~270 W/cm2 average surface heat flux and to a maximum local burnup greater than 8 × 1021 fissions/cm3 in the Advanced Test Reactor as part of the RERTR-8 experiment. As part of the non-destructive examinations that were performed on both fuel plates, detailed thickness measurements using a high-fidelity measurement bench were performed on one fuel plate and a segment of the second fuel plate. This paper provides the first reported results of such high-resolution thickness measurements for U3Si2/Al dispersion fuel plates, containing primarily the U3Si2 fuel phase, irradiated at such power levels to high burnup. For destructive examination using optical metallography, samples were generated from both irradiated plates. Localized regions of high swelling (characteristic of internal blistering) were observed on the surface of both fuel plates, suggesting that the performance limits had been reached for each plate. Destructive examinations showed that the fuel particles that are primarily U3Si2, which become amorphous during irradiation, in both plates contained relatively large fission gas bubbles with evidence of fission gas bubble interconnection.

Wachs, Daniel M.↗
DOE OSTI2022

Friction stir welding and self-ion irradiation effects on microstructure and mechanical properties changes within oxide dispersion strengthened steel $\mathrm{MA956}$

We report the joining process for oxide dispersion strengthened (ODS) alloys remains a key challenge facing the nuclear community. The microstructure and mechanical properties were characterized in the base material and friction stir welded ODS MA956 irradiated with 5 MeV Fe 2+ ions from 400 to 500°C up to 25 dpa. Nanoindentation was performed to assess changes in hardness and yield stress, and the dispersed barrier hardening (DBH) model was applied to described results. A combination of scanning transmission electron microscopy (STEM) and atom probe tomography (APT) were used to assess evolution of the microstructure including dispersoids, network dislocations and dislocation loops, nanoclusters, and solid solution concentrations. Overall, softening was observed as a result of increased dose, which was exacerbated at 500°C. The formation and coarsening of new dispersoids was noted while nanoclusters tended to dissolve in the base material, and were not observed in the stir zone. Solute nanocluster evolution was identified as a primary driver of the changes in mechanical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Contributions to the mechanistic understanding of the microstructural evolution in irradiated U-Mo dispersion fuel

Here, advanced microstructural characterization techniques, such as scanning electron microscopy (SEM) and scanning transmission electron microscopy - energy dispersive x-ray spectroscopy (STEM-EDS), were used to interpret the fuel microstructure evolution and fission products behavior in U-Mo dispersion fuel irradiated in the Advanced Test Reactor (ATR) as part of the European Mini-Plate Irradiation Experiment (EMPIrE) test. The larger as-fabricated fuel grain size achieved by heat-treating the U-Mo powder resulted in slower high burnup structure (HBS) development and reduced fission gas porosity. Slower HBS kinetics was observed at the fuel kernels’ periphery, which contained smaller and less fission gas bubbles at all fission densities (FDs) investigated and was attributed to a locally reduced damage density and fission products concentration, as corroborated with Monte Carlo simulations. The non-refined grains at the fuel kernel periphery hosted a perfectly ordered fission Gas Bubble Superlattice (GBS) up to 6.3 × 10 21 fissions/cm 3 . Nano-scale STEM-EDS analysis presented in this study provided useful information on the GBS characteristic morphology and evolution in U-Mo fuel. The concentration of fission gas in the GBS progressively increased with FD, pointing to an evolution of the nanobubble pressure status with irradiation. A possible connection between the GBS collapse and HBS onset is proposed for which there exists a threshold in the misorientation of the refined sub-grains above which the GBS stability during irradiation is no longer preserved, resulting in the GBS collapse.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Relationship between dislocations and residual stresses in cold-drawn pearlitic steel analyzed by energy-dispersive X-ray diffraction

We analyzed the dislocation distribution of cold-drawn pearlitic-steel wire by using the line-profile analysis based on the energy dispersive X-ray diffraction (EDXD). Although this line-profile analysis requires a high resolution in reciprocal space, the resolution for EDXD is generally poor due to the energy resolution of the detector. Our analysis demonstrated that the resolution in the reciprocal space can be maximized at small scattering angles. Using the line-profile analysis based on the EDXD, the microstructural parameters such as the crystallite size and the dislocation density of the ferrite phase in the pearlitic steel were successfully analyzed. In addition, the distribution of the residual stress of the ferrite phase of a pearlitic steel wire was also analyzed using the EDXD measurement. - Highlights: • Energy dispersive X-ray diffraction is applied to the line-profile analysis. • Distribution of dislocations in ferrite in the pearlitic steel wire is analyzed. • Relationship between dislocations and residual stress is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Controllable synthesis, shape evolution, and luminescence properties of uniform and well-dispersed NaEuF{sub 4} microcrystals through hydrothermal route

Graphical abstract: Sodium europium fluorides NaEuF{sub 4} microcrystals have been prepared via a facile hydrothermal route. The possible growth mechanism and the luminescent properties of the as-prepared microcrystals have been discussed. - Highlights: • Sodium europium fluorides NaEuF{sub 4} microspheres were prepared by a facile hydrothermal route. • The as-prepared samples NaEuF{sub 4} and EuF{sub 3} exhibit respective red or orange-red emissions. • These finding may find potential applications in the fields of color display, UV laser and biomedicine. - Abstract: Sodium europium fluorides NaEuF{sub 4} microcrystals with uniform and well-dispersed shapes and dimensions have been prepared via a facile hydrothermal route using Na{sub 3}Cit as the chelating ligand and shape modifier. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive X-ray (EDX) and photoluminescence spectra (PL) were taken to characterize the samples. A series of controlled experiments reveal that the trisodium citrate (Na{sub 3}Cit) content, pH value of the initial solution, and reaction time have an indispensable role on the phase, size, and morphology of the as-prepared microcrystals. Based on the experimental results, the possible growth mechanism of the microcrystals prepared under different conditions was proposed. Moreover, we systematically investigated the luminescent properties of the as-prepared microcrystals with different morphologies obtained under different amounts of Na{sub 3}Cit, which have potential application in the fields of color display, UV laser and biomedicine.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Characterization and dispersibility of improved thermally stable amide functionalized graphene oxide

Graphical abstract: Improved thermal stability and surface study of amide functionalized graphene oxide. - Highlights: • Amide functionalized graphene oxides (AGOs) were synthesized from aniline, 2-aminothiazole and 2-aminopyrimidine. • Achieved enhancement in thermal stability of AGOs as compare to GO. • AGOs are found to be highly dispersible in water, DMSO and DMF. • Dispersibility is stable for more than two and half months. - Abstract: Amidation of graphene oxide (GO) with aniline, 2-aminothiazole and 2-aminopyrimidine results in the synthesis of amide functionalized graphene oxides (AGOs). Scanning electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA), UV–vis and Raman spectroscopy were used to investigate the properties of AGOs. It was found that, contrary to GO, AGOs are soluble in water, dimethyl sulfoxide, dimethylformamide and can be stabilized for months. TGA of AGOs shows the major weight loss above 670 °C as compared to GO in which significant weight loss occurs near 200 °C. Thus AGOs show strong improvement in thermal properties.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Synthesis and magnetic properties of bundled and dispersed Co{sub 3}O{sub 4} nanowires

Highlights: • Co{sub 3}O{sub 4} nanowires possessed the same diameter and the different interwires distance. • All samples possessed antiferromagnetism and superparamagnetism at high temperature. • The exchange bias effect was observed at low temperature. • The surface spin coupling restrained the surface effect of magnetic nanostructures. - Abstract: The magnetic Co{sub 3}O{sub 4} nanowires were synthesized using the templates of SBA-15, and then the well-dispersed nanowires (D-wires) were separated from the bundled ordered nanowires (B-wires) with the centrifugal technique. TEM images indicated that D-wires were highly dispersed Co{sub 3}O{sub 4} nanowires and B-wires existed in bundles. All samples possessed the antiferromagnetism and superparamagnetism at high temperature. After revealing the intrinsic magnetic properties of Co{sub 3}O{sub 4} nanowires with D-wires, the magnetic behavior of B-wires was discussed in detail, and then the magnetic interaction between neighboring nanowires could be deduced. The exchange bias effect from the body Co{sub 3}O{sub 4} antiferromagnetism and surface ferromagnetism was observed at low temperature. The magnetization of B-wires was higher than that of D-wires, which was attributed to the constraint of the surface spin coupling between the neighboring nanowires to the surface affect of nanostructures.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Highly dispersive platinum nanoparticles supporting on polyaniline modified three dimensional graphene and catalyzing methanol oxidation

Highlights: • 3D corrugated graphene-based Pt/3D-GNs (PANI) was synthesized by hydrothermal process. • Polyaniline (PANI) was formed in-situ with the aid of catalysis from generated Pt. • Pt particles has better dispersion and stronger interaction with support due to PANI. • Pt/3D-GNs (PANI) exhibits larger active surface area and faster electron transfer. • Pt/3D-GNs (PANI) shows better electrocatalytic performances than Pt/3D-GNs and Pt/C. - Abstract: Direct methanol fuel cells have been attracting serious attention due to its high power density and low pollution, and huge effort has focused on its electrode catalysts. Here, a hydrothermal process was used to synthesize Pt/three dimensional graphene (polyaniline) catalyst (Pt/3D-GNs (PANI)), in which PtCl{sub 4}{sup 2−} and graphene oxide (GO) were reduced synchronously. Especially, aniline was polymerized to form polyaniline (PANI) in situ, catalyzed by pre-generated Pt. After cooling by liquid nitrogen, graphene sheets (GNs) were converted into three dimensional (3D) corrugated graphene. The introduction of PANI promotes formation of 3D graphene structure and favors optimal distribution of Pt particles. Synergistic effect of 3D corrugated graphene structure, highly dispersive Pt nanopartilces and fast electron transfer of support makes Pt/3D-GNs (PANI) have superior electrocatalysis for methanol oxidation. Electrochemical tests show that Pt/3D-GNs (PANI) exhibits much higher electrocatalytic activity (1172 mA mg{sup −1}), better stability and improved CO tolerance in comparison with commercial Pt/C.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2026

A synergistic approach to improve the cellulose nanofibril dispersion in poly(lactic acid) composites as feedstocks for extrusion-based additive manufacturing

Hybrid fiber-reinforced polymer composites (HFRPs) are multifunctional materials that bear more than one characteristic benefit. In this study, hybrid cellulose fibers, e.g., pulp fiber (PF) and cellulose nanofibril (CNF), were used for reinforcing poly(lactic acid) (PLA). A synergistic approach was applied to disperse CNF. The low-surface-tension solvent (ethanol), together with PF templating, assisted the dispersion of CNF in PLA. The HFRP achieved a higher tensile strength (∼70 MPa, 29% increase from PLA) and modulus (∼7 GPa, 46% increase from PLA), as well as a higher heat deflection temperature (∼60℃, 6℃ increase compared to neat PLA), compared to single-reinforcement FRPs. Additionally, the formulation was demonstrated to be potentially suitable for large-scale additive manufacturing.

Bista, Bivek [University of Maine]↗
DOE OSTI2023

Nonlinear optics from hybrid dispersive orbits

Here in this paper we expand the technique of characterizing nonlinear optics from off-energy closed orbits (NOECO) to cover harmonic sextupoles in storage rings. The existing NOECO technique has been successfully used to correct the chromatic sextupole errors on the MAX-IV machine (Olsson et al., 2020), however, it does not account for harmonic sextupoles, which are still widely used on many other machines. By generating vertical dispersion with chromatic skew quadrupoles, a measurable chromatic function dependence on harmonic sextupoles can be observed on hybrid dispersive orbits. Proof of concept of this technique was accomplished by simulations and beam measurements on the National Synchrotron Light Source II (NSLS-II) storage ring.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Automated reactor physics analysis framework of High Flux Isotope Reactor low-enriched uranium silicide dispersion fuel designs

The High Flux Isotope Reactor (HFIR) is a versatile research reactor that provides one of the highest steady-state neutron fluxes of any reactor in the world. The HFIR reactor physics team investigated the conversion of the current 93 wt% highly enriched uranium U 3 O 8 -Al dispersion fuel to a 19.75% low-enriched uranium (LEU) U 3 Si 2 -Al dispersion fuel. The team continuously develops a Python module to streamline the analysis steps required for an LEU core design to ensure reproducible and agile design iteration. The Python module automates the data processing between analysis steps and automates the input perturbation for branch calculations and design changes. The automated framework has proven to significantly increase the efficiency and reproducibility of the reactor physics team to design High Flux Isotope Reactor (HFIR) LEU cores and thoroughly analyze performance metrics, safety metrics, and thermal safety margins. Consequently, the team can now respond rapidly to fuel fabrication engineer and thermal-hydraulic-structural analyst requests. Numerous combinations of LEU fuel designs are explored, of which two LEU fuel designs are presented here in this paper: a low density silicide design, and a high-density silicide design. Results show that both designs meet or exceed safety and performance metrics with exception for minor differences caused by the hardened spectrum from LEU.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Dispersion of modified fumed silica in elastomeric nanocomposites

In polymer nanocomposites, surface modification of silica aggregates can shield Coulombic interactions that inhibit agglomeration and formation of a network of agglomerates. Surface modification is usually achieved with silane coupling agents although carbon-coating during pyrolytic silica production is also possible. Pyrogenic silica with varying surface carbon contents were dispersed in styrene-butadiene (SBR) rubber to explore the impact on hierarchical dispersion, the emergence of meso-scale structures, and the rheological response. Pristine pyrogenic silica aggregates at concentrations above a critical value (related to the Debye screening length) display correlated meso-scale structures and poor filler network formation in rubber nanocomposites due to the presence of silanol groups on the surface. Here, in the present study, flame synthesized silica with sufficient surface carbon monolayers can mitigate the charge repulsion thereby impacting network structural emergence. The impact of the surface carbon on the van der Waals enthalpic attraction, a * , is determined. The van der Waals model for polymer nanocomposites is drawn through an analogy between thermal energy, k B T, and the accumulated strain, γ. The rheological response of the emergent meso-scale structures depends on the surface density of both carbon and silanol groups.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Integrated modeling methodology for ash agglomeration in poly-disperse fluidized beds using particle population framework

This article discusses a unique agglomeration modeling methodology developed based on binary collisions to combine the effects of heterogeneity in ash chemistry and granular physics. A simple population balance is defined to find changes in the particle size distribution (PSD) of a fluidized bed. Thermodynamic equilibrium calculations and a computational fluid dynamics (CFD) code, are used to obtain hydrodynamic parameters. A method to calculate and use a distribution of collision frequencies in fluidized beds, corresponding to a poly-disperse particle size distribution, was developed in order to incorporate the particle level heterogeneities. A distribution of collision frequencies obtained for poly-dispersed particles showed a three orders of magnitude higher collision frequency amongst the smaller particles than the coarser ones, at the initiation of agglomeration. Ash agglomeration occurred when the slag amount (binder) was less than 10 wt% at temperatures <850 °C for Pittsburgh No. 8 coal.

42 ENGINEERING↗
DOE OSTI2023

Stationary and drone-assisted methane plume localization with dispersion spectroscopy

This work presents stationary and mobile retroreflector-based remote sensing techniques for methane leak localization and quantification using chirped laser dispersion spectroscopy equipped with a custom laser transceiver capable of continuous tracking of a flying drone and coupled with inverse atmospheric gas dispersion modeling. The techniques demonstrate the ability to localize leaks as low as 0.13 g CH 4 ·s -1 , which are up to 25 times smaller than those typically observed at natural gas facilities, as well as actively track a moving retroreflector mounted on a lightweight (~250 g) drone to enable spatial plume reconstruction. This system exhibited a 2.3 ppm-m sensitivity over pathlengths of 40–150 m. Source localization to within ±7 m is demonstrated using a modified horizontal radial plume mapping technique with a stationary retroreflector grid. Meanwhile, the mobile system utilizing a drone-mounted retroreflector is able to localize a controlled release within ±1 m of its source location and estimate leak rates using inversion techniques assuming type B Gaussian plume stability class within ±30% error with respect to the actual low flow rate releases.

47 OTHER INSTRUMENTATION↗
DOE OSTI2014

Effect of Mo Dispersion Size and Water Vapor on Oxidation of Two-Phase Directionally Solidified NiAl-9Mo In-Situ Composites

Oxidation of two-phase NiAl-9Mo eutectics with 3 different growth rates/2nd phase Mo dispersion sizes were investigated at 900 C in air and air with 10% water vapor. Good oxidation resistance via alumina formation was observed in dry air, with Mo volatilization loss minimized by fine submicron Mo dispersions. However, extensive Mo volatilization and in-place internal oxidation of prior Mo phase regions was observed in wet air oxidation. Ramifications of this phenomenon for the development of multi-phase high-temperature alloys are discussed

Brady, Michael P↗
DOE OSTI2020

The 1 H T 1 dispersion curve of fentanyl citrate to identify NQR parameters

We report the 1 H T 1 dispersion curve between 0 and 5 MHz for the synthetic opioid fentanyl citrate (C 28 H 36 N 2 O 8 ). The structures in the curve can be used to estimate the 14 N nuclear quadrupole resonance (NQR) frequencies of the material. Density functional theory predictions of the NQR parameters of several fentanyl citrate compounds are also reported. The predictions for the aniline nitrogen are consistent with structures in the observed T 1 data. To help interpret the fentanyl citrate results the T 1 dispersion curve for the explosive ammonium nitrate is also presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Improved scaling laws for the shock-induced dispersal of a dense particle curtain

Here, experiments were performed within Sandia National Labs’ Multiphase Shock Tube to measure and quantify the shock-induced dispersal of a shock/dense particle curtain interaction. Following interaction with a planar travelling shock wave, schlieren imaging at 75 kHz was used to track the upstream and downstream edges of the curtain. Data were obtained for two particle diameter ranges ( $d_{p}=106{-}125$ , $300{-}355~\unicode[STIX]{x03BC}\text{m}$ ) across Mach numbers ranging from 1.24 to 2.02. Using these data, along with data compiled from the literature, the dispersion of a dense curtain was studied for multiple Mach numbers (1.2–2.6), particle sizes ( $100{-}1000~\unicode[STIX]{x03BC}\text{m}$ ) and volume fractions (9–32 %). Data were non-dimensionalized according to two different scaling methods found within the literature, with time scales defined based on either particle propagation time or pressure ratio across a reflected shock. The data refelct that spreading of the particle curtain is a function of the volume fraction, with the effectiveness of each time scale based on the proximity of a given curtain’s volume fraction to the dilute mixture regime. It is observed that volume fraction corrections applied to a traditional particle propagation time scale result in the best collapse of the data between the two time scales tested here. In addition, a constant-thickness regime has been identified, which has not been noted within previous literature.

42 ENGINEERING↗