Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Particle characterization”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches

Sediment-associated natural organic matter (NOM) is a complex assemblage of organic molecules with a wide range of sizes, functional groups, and structures, which is intricately associated with mineral particles. Organic carbon (OC) concentrations in subsurface sediments are typically 10 to 200 times lower than in surface soils, posing a distinct challenge for characterization. A range of chemical extractions were evaluated for extraction of NOM, and a NOM extraction scheme was developed using a combination of sequential extraction with water (MQ) and sodium pyrophosphate at pH 10 (PP), and purification by dialysis and solid phase extraction in order to isolate different fractions of sediment-associated NOM. Analysis of these different NOM fractions was then carried out by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The OC extraction efficiency of the tested extractions followed the order PP>NaOH>HCl=hydroxylamine hydrochloride>dithionite. Greater concentrations of OC in PP vs NaOH extracts suggest that metal complexation and/or ligand exchange plays an important role in OC stabilization. Characterization of different pools of extraction NOM by FITR shows that the water soluble fraction has a higher fraction of aliphatic and carboxylic groups, while the PP fractions have higher C=C groups. This trend from aliphatic to more aromatic is also supported by the UV-Vis and ESI-FTICR-MS data.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2022

Investigation of Nano-Scale Segregation in Nanostructured Ferritic Alloy 14YWT after Heavy Ion Irradiation

Oxide-dispersion-strengthened (ODS) steels, which contain nano-scale Y-Ti-O particles, are being considered for high-temperature radiation environments of nuclear reactors. It is important to accurately characterize the structure of grain boundaries and understand the behavior of segregation at grain boundaries in ODS steels during irradiation. The effect of heavy ion irradiation at 700 °C on Nanostructured Ferritic Alloy 14YWT was investigated using Atom Probe Tomography. Enrichment of Cr occurs at the grain boundaries as well as at nano oxide particle surfaces in the unirradiated sample. The enrichment of Ti and Y at a grain boundary corresponds with Y-Ti-O nano oxide particles with larger size compared to those in the grain, and the Cr enrichment is particularly accentuated at these larger nano oxide particles. The segregation of W occurs at the grain boundaries that are without nano oxide particles. O is segregated at grain boundaries without oxide particles after irradiation. The segregation behavior of Cr, W, Ti, and Y at the grain boundary in the irradiated samples is similar to that in the unirradiated sample. The nano oxide particles embedded in the grain boundary are a primary reason for the increase in Cr segregation at the grain boundary.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Novel anaerobic selenium oxyanion reducers native to FGD wastewater for enhanced selenium removal

Biological treatment is a recognized approach for removing selenate and selenite oxyanions present in flue gas desulfurization (FGD) wastewater. However, the knowledge of the specific microbial species or communities responsible for reducing water-soluble selenium oxyanions to insoluble elemental selenium remains limited. In addition, the selenium oxyanion reduction genes and pathways have yet to be understood in these wastewaters. This study characterizes selenium oxyanion-reducing bacteria (SeRB) native to FGD wastewater, and the resulting elemental selenium particles formed. By selecting native SeRB microbes in a defined media, a novel resolution of these organisms has been achieved. This research identifies previously unrecognized selenium oxyanion-reducing capabilities in Anaerosolibacter, alongside predominant SeRB from Mesobacillus and Tepidibacillus genera. This work encompasses both 16S and metagenomic techniques to recover novel metagenome-assembled genomes, distinct to this environment. The biogenic selenium produced by these organisms was predominantly of elemental selenium, either amorphous or with a hexagonal structure. This study identifies the SeRB present in FGD wastewater and characterizes their selenium products, offering crucial insights to enhance the efficiency of biological treatment strategies and the potential of selenium recovery from this industrial waste.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Ex Situ Investigation of Anisotropic Interconnection in Silicon-Titanium-Nickel Alloy Anode Material

Herein we investigate the nanostructural evolution of Silicon-Titanium-Nickel (Si-Ti-Ni) ternary alloy material synthesized by melt spinning process for advanced lithium-ion battery anode. The synthesized material was found to have nano-Silicon particles dispersed in the Ti 4 Ni 4 Si 7 (STN) alloy buffering matrix and was characterized by X-ray diffraction (XRD), High resolution- transmission electron microscope (HR-TEM), Scanning transmission electron microscopes - energy dispersive X-ray spectrometer (STEM-EDS), and electrochemical performance test. The role of STN matrix is to accommodate the volume expansion stresses of the dispersed Si nanoparticles. However, an interesting behavior was observed during cycling. The Si nanoparticles were observed to form interconnection channels growing through the weak STN matrix cracks and evolving to a network isolating the STN matrix into small puddles. In conclusion, this unique nanostructural evolution of Si particles and isolation of the STN matrix failing to offer significant buffering effect to the grown Si network eventually accelerates more volume expansions during cycling due to less mechanical confinement and leads to performance degradation and poor cycle stability.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Characteristics of suprathermal H(+) and He(++) in plasmoids in the distant magnetotail

Rest frame distribution functions were obtained for suprathermal H(+) and He(2+) ions during 20 particle intensity increases that were observed in the distant magnetotail by ISEE-3. All of these increases were characterized by isotropic, approximately 100-keV electrons, preceded by beaming electrons and velocity-dispersed protons distributions whose signatures are typically associated with plasmoids. In each of the plasmoids, both H(+) and He(2+) are found to be convected tailward, with speeds that range from 200 to 1000 km/sec. The acceleration mechanism is found to depend on particle velocity, and it is established that the solar wind is a dominant plasma source. The plasmoids appear to be expanding at about 100 km/sec during their tailward propagation.

Gloeckler, G.↗
DOE OSTI2016

Prompt Gamma Neutron Activation Analysis of Niobium for Characterization of Light Interstitials

High purity niobium metal is used in the construction of superconducting radio frequency (SRF) cavities in superconducting particle accelerators. The Spallation Neutron Source at Oak Ridge National Laboratory is an example of an SRF linear accelerator (LINAC) that requires this high purity niobium material. For the SRF cavities to function well, it is necessary that the cavity wall have a high thermal conductivity so that the radio frequency (RF) power can be dissipated into the liquid helium coolant. For a high thermal conductivity of the niobium metal to be achieved, it is required to have extremely low levels of impurities. The current industry standard for determining the quality of the high purity niobium material is the residual resistivity ratio (RRR) technique. In this technique, the temperature dependency of a niobium metal sample is determined at temperatures near that of liquid helium in order to establish where the superconducting jump occurs. With this method, it is possible to find the general level of impurity of the metal sample, but not the specific elements that are contributing to the impurity. The impurities that are of particular interest to manufacturers of niobium for SRF use are tantalum and light interstitials, such as hydrogen, carbon, nitrogen, and oxygen. In this research, we focus on determining the analytical sensitivity of the detector system and characterizing the light interstitial content in high purity niobium metal through the use of Prompt Gamma Neutron Activation Analysis (PGNAA). PGNAA is an analytical technique that can be utilized to determine the concentration of elemental components in a wide variety of materials with high precision and reproducibility. In this process, neutrons bombard a sample material, causing the emission of gamma rays from the sample. Each element emits a unique spectrum of gamma radiation, which allows for identification of the elements present in the sample. (authors)

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Oxidation Behavior of Zirconium Diboride Nanoparticles

The products of oxidation of ZrB{sub 2} powders with average particle sizes of ~100 and ~30 nm by atmospheric oxygen under isothermal conditions and during heating have been characterized by thermal analysis, X-ray diffraction, scanning electron microscopy, IR frustrated total internal reflection spectroscopy, energy dispersive X-ray analysis, and elemental analysis. The oxidation onset has been observed at 594 and 396°C, respectively. Oxidation at temperatures of ≥800°C leads to the formation of boron oxide and monoclinic ZrO{sub 2}, independent of the particle size of ZrB{sub 2}. The reaction rate constants for the oxidation of ZrB{sub 2} nanoparticles ~100 and ~30 nm in size have been determined to be 0.03, 0.15, and 0.31 h{sup –1} at 600, 650, and 700°C and 0.11, 0.35, and 0.81 h{sup –1} at 500, 600, and 700°C, respectively. The apparent activation energies for the oxidation of the ZrB{sub 2} nanoparticles ~100 and ~30 nm in size are 161 ± 4 and 62 ± 3 kJ/mol, respectively, as evaluated from the temperature dependence of the rate constants at the above temperatures.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

A New Approach to Charged Particle Slowing Down and Dispersion

The process by which super-thermal ions slow down against background Coulomb potentials arises in many fields of study. In particular, this is one of the main mechanisms by which the mass and energy from the reaction products of fusion reactions is deposited back into the background. Many of these fields are characterized by length and time scales that are the same magnitude as the range and duration of the trajectory of these particles, before they thermalize into the background. This requires numerical simulation of this slowing down process through numerically integrating the velocities and energies of these particles. This paper first presents a simple introduction to the required plasma physics, followed by the description of the numerical integration used to integrate a beam of particles. This algorithm is unique in that it combines in an integrated manner both a second-order integration of the slowing down with the particle beam dispersion. These two processes are typically computed in isolation from each other. A simple test problem of a beam of alpha particles slowing down against an inert background of deuterium and tritium with varying properties of both the beam and the background illustrate the utility of the algorithm. This is followed by conclusions and appendices. The appendices define the notation, units, and several useful identities.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Combustion of Silane-Hydrogen-Nitrous oxide Mixtures: Analysis of Laminar Flame Propagation and Condensed Products

The laminar burning rate, the explosion pressure, and the pressure rise coefficient have been measured for silane-nitrous oxide-argon mixtures using the spherically expanding flame technique in a constant volume combustion chamber. For these three parameters, the values obtained were higher than for hydrogen-nitrous oxide-argon and typical hydrocarbon-based mixtures. As an example, a maximum burning rate of 1800 g/m 2 s was measured at 101 kPa, whereas under similar conditions, a maximum burning rate around 950 g/m 2 s has been reported for hydrogen-nitrous oxide-argon mixtures. Here, the condensed combustion products formed in the silane-nitrous oxide-argon flames were sampled and characterized using electron micrograph, electronic diffraction, energy-dispersive spectroscopy, and X-ray powder diffraction. For all equivalence ratios, silica spherical particles with a mean diameter in the range 200-300 nm were observed. In addition, for mixtures with Φ ≥2.2, silicon nanowires were formed. X-ray diffraction experiments showed that the silicon nanowires are composed of a material referred to as “metal silicon” characterized by a cubic structure (lattice parameter: a = 5.425 Å) with the Fm-3m space group.

42 ENGINEERING↗
NASA NTRS2009

The Orbiting Wide-Angle Light Collectors (OWL) Mission for Charged-Particle Astronomy

The space-based OWL mission is designed to perform high-statistics measurements of ultra-high-energy cosmic rays (UHECR) using the Earth's atmosphere as a vast particle calorimeter, furthering the field of charged-particle astronomy. OWL has been developed in formal NASA instrument and mission studies and is comprised of two large telescopes separated by approx.600 km in 1000 km, near-equatorial orbits to stereoscopically image the near-UV air fluorescence emitted by UHECR-induced particle cascades. The High Resolution Fly's Eye (HiRes) Collaboration, and subsequently the Pierre Auger Observatory, recently reported confirmation of the expected Greisen-Zatsepin-Kuzmin (GZK) suppression of the UHECR flux above a few times 10(exp 19) eV. This observation is consistent with the majority of UHECR originating in astrophysical objects and reduces the need to invoke exotic physical processes. Particles observed above the GZK threshold energy must have come from sources within about 100 Mpc from the Earth. The small particle deflection angles expected at UHECR energies, with standard assumptions of extragalactic magnetic fields, are on the order of 1 degree. Thus by observing particles above the GZK threshold with sufficient exposure, there is the potential of identifying and characterizing individual UHECR sources. Auger has reported significant anisotropy in the arrival directions of UHECR at energies above about 6 10(exp 19) eV observed in the South, and a correlation to AGN in the 12th VCV catalog, suggesting that the sources of UHECR are traced by the distribution of luminous matter in the Universe. However, with similar statistics and the same event selection criteria, HiRes observations in the North are consistent with isotropy. Extended observations by Auger-South, by Telescope Array in the North, and possibly by the proposed Auger-North, will further these investigations. However, much greater exposures will be required to fully identify individual sources and measure their cosmic ray spectra. A five-year OWL mission would deliver approximately 10(exp 6)sq km/sr/yr of exposure with full aperture reached at approx. 10(exp 19) eV. The baseline 3 m optical aperture OWL telescopes with 45 degree full field-of-view are easily accomodated on a single conventional launch vehicle. On orbit, the simultaneous viewing of the same volume of atmosphere allows for precise stereo event reconstruction, which is nearly independent of the inclination of the particle track and tolerant of atmospheric conditions. The availability of monocular operation provides increased reliability or can be employed to increase the instantaneous aperture. In stereo mode, OWL is also capable of fully reconstructing horizontal or upward-moving showers and so has unmatched sensitivity to neutrino-induced events. The details of the OWL mission will he presented and its science capabilities will be discussed.

Mitchell, John↗
NASA NTRS1978

Studies of acceleration processes in the corona using ion measurements on the solar probe mission

The energy spectra and composition of particles escaping from the Sun provide essential information on mechanisms responsible for their acceleration, and may also be used to characterize the regions where they are accelerated and confined and through which they propagate. The suprathermal energy range, which extends from solar wind energies (approximately 1 KeV) to about 1 MeV/nucleon, is of special interest to studies of nonthermal acceleration processes because a large fraction of particles is likely to be accelerated into this energy range. Data obtained from near earth observations of particles in the suprathermal energy range are reviewed. The necessary capabilities of an a ion composition experiment in the solar probe mission and the required ion measurements are discussed. A possible configuration of an instrument consisting of an electrostatic deflection system, modest post acceleration, and a time of flight versus energy system is described as well as its possible location on the spacecraft.

Gloeckler, G.↗
DOE OSTI2019

Synthesis and Properties of Porous Ti-20 wt.% HA Nanocomposites

In the present study, porous titanium-20 wt.% hydroxyapatite nanocomposites were produced by the combination of mechanical alloying and powder metallurgical process with the addition of titanium hydride particles as the blowing agent. The powder mixture of Ti, HA and spacer particles were milled, pressed and heat-treated to decompose the hydride particles and to sinter into highly porous Ti-HA materials. The resulting microstructures were characterized using x-ray diffraction and scanning electron microscope with energy-dispersive spectrometry. The porosity, compressive strength and corrosion resistance of the porous nanocomposites were investigated. The results show that the compressive strength of porous Ti-HA can be tailored between 210 and 497 MPa by changing the content of blowing agent between 25 and 75%. The increase in the weight ratio of titanium hydride (from 25 to 75%) causes almost a twofold increase in the porosity and decreases the corrosion resistance (by almost two orders of magnitude). The present study has demonstrated that the porous Ti-HA nanocomposites are promising scaffold biomaterials for bone tissue engineering by virtue of their appropriate mechanical and corrosion properties and highly porous structure.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Utilizing a Novel Acoustic Backscatter Array to Characterize Waste Consolidation and Settling in a Horizontal Flow Clarifier - 16051

As part of a collaboration between the University of Leeds, Sellafield Ltd and MMI Engineering Ltd, bespoke acoustic instrumentation and numerical simulation methods have been established to optimize nuclear legacy waste transfers. Specifically, a new ultrasonic measurement system has been developed, allowing suspended particle concentration and consolidation to be measured remotely. This technology has been combined with computational fluid dynamics (CFD) modelling of settling particulate systems, permitting full characterization, simulation and prediction of sludge separation processes. Presented here are experimental and numerical results on the transport and settling behavior of non-active nuclear-analogue suspensions in two flow geometries: gravitational settling of glass dispersions in a 250-liter column; and transport and sedimentation of flocculated calcite in a close-to-full-scale clarifier (9 m{sup 3} total volume and 4.8 m{sup 2} length). In addition, details of the design, construction and calibration of a custom-built Ultrasonic Array Research Platform (UARP) are described. Settling column results suggested that particle concentration changes could be simulated with good accuracy by a CFD model (developed using the open source OpenFOAM framework) when compared to measured samples. Large-scale clarifier trials were used to assess the effectiveness of the UARP controller with an attached in situ acoustic backscatter array (ABA). The ABA consisted of 8 transducers angled down at 20 deg. to the vertical, pulsing at 2-2.5 MHz in cycles (covering 1.8 m total depth). In comparison to a range of sampled concentrations across the length of the clarifier, results confirmed that the UARP-ABA system was highly successful at characterizing these complex flows over several hours of operation, allowing visualization of depth-wise bulk density changes and bed build-up over time. Collectively, this work highlights the capability of these tools to monitor and optimize a number of current waste transfer operations at Sellafield, with further potential applications for solid-liquid separations across waste, water treatment and minerals engineering industries. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1994

Climatology of large-scale isentropic mixing in the Arctic winter stratosphere from analyzed winds

Dynamic isolation of the winter Arctic circumpolar vortex is studied using analyzed winds derived from geopotential height fields. Isentropic trajectories are calculated for assemblages of particles initialized on uniform latitude-longitude grids. Transport across isolines of Ertel potential vorticity (PV) is used to characterize the mixing processes of ejection of vortex air and entrainment of midlatitude air into the vortex. During January and February a barrier to mixing, where exchange of air is inhibited, typically forms near the vortex boundary. At 450 K, transport across the barrier is predominantly in the form of thin filaments of particles ejected from the vortex. These filaments tend to wrap around the vortex, creating a layered structure of vortex and midlatitude air at the vortex edge. Near or total splits of the vortex into two or more distinct vortex fragments are quite common based on these trajectory calculations. Significant entrainment deep into the vortex is rare and results from only a limited number of the splitting events. During December and March the mixing barrier is less evident due to nonconservative factors during the spin-up and breakdown of the vortex, respectively. In December both ejection and entrainment are only weakly inhibited by the mixing barrier. Exchange in March is dominated by ejection of air from the vortex.

Dahlberg, Steven P.↗
DOE OSTI2018

Electrosynthesis of Ti{sub 5}Si{sub 3}, Ti{sub 5}Si{sub 3}/TiC, and Ti{sub 5}Si{sub 3}/Ti{sub 3}SiC{sub 2} from Ti-Bearing Blast Furnace Slag in Molten CaCl{sub 2}

Ti{sub 5}Si{sub 3}, Ti{sub 5}Si{sub 3}/TiC, and Ti{sub 5}Si{sub 3}/Ti{sub 3}SiC{sub 2} have been electrochemically synthesized from the Ti-bearing blast furnace slag/TiO{sub 2} and/or C mixture precursors at a cell voltage of 3.8 V and 1223 K to 1273 K (950 °C to 1000 °C) in molten CaCl{sub 2}. The pressed porous mixture pellets were used as the cathode, and a solid oxide oxygen-ion-conducting membrane (SOM)-based anode was used as the anode. The phase composition and morphologies of the cathodic products were systematically characterized. The final products possess a porous nodular microstructure due to the interconnection of particles. The variations of impurity elements, i.e., Ca, Mg, and Al, have been analyzed, and the result shows that Ca and Mg can be almost completely removed; however, Al cannot be easily removed from the pellet due to the formation of Ti-Al alloys during the electroreduction process. The electroreduction process has also been investigated by the layer-depended phase composition analysis of the dipped/partially reduced pellets to understand the detailed reaction process. The results indicate that the electroreduction process of the Ti-bearing blast furnace slag/TiO{sub 2} and/or C mixture precursors can be typically divided into four periods, i.e., (i) the decomposition of initial Ca(Mg,Al)(Si,Al){sub 2}O{sub 6}, (ii) the reduction of Ti/Si-containing intermediate phases, (iii) the removal of impurity elements, and (iv) the formation of Ti{sub 5}Si{sub 3}, TiC, and Ti{sub 3}SiC{sub 2}. It is suggested that the SOM-based anode process has great potential to be used for the direct and facile preparation of Ti alloys and composites from cheap Ti-containing ores.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Investigation of Mechanical Properties of Parts Fabricated with Gas- and Water-Atomized 304L Stainless Steel Powder in the Laser Powder Bed Fusion Process

In this report the use of gas-atomized powder as the feedstock material for the Laser Powder Bed Fusion (L-PBF) process is common in the Additive Manufacturing (AM) community. Although gas-atomization produces powder with high sphericity, its relatively expensive production cost is a downside for application in AM processes. Water atomization of powder may overcome this limitation due to its low cost relative to the gas-atomization process. In this work, gas- and water-atomized 304L stainless steel powders were morphologically characterized through Scanning Electron Microscopy (SEM). The water-atomized powder had a wider particle size distribution and exhibited less sphericity. Measuring powder flowability using the Revolution Powder Analyzer (RPA) indicated that the water-atomized powder had less flowablility than the gas-atomized powder. Through examining the mechanical properties of L-PBF fabricated parts using tensile tests, the gas-atomized powder had significantly higher yield tensile strength and elongation than the water-atomized powder, however, their ultimate tensile strengths were not significantly different.

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

Design of PGM-free cathodic catalyst layers for advanced PEM fuel cells

Here, the design of cathodic catalysts layer (CCL) consisted of Platinum Group Metal-free (PGM-free) electrocatalysts was done by catalyst coated membrane approach. Three different Fe-Mn-N-C compounds were synthesized with Fe:Mn ratio of 1:1, 2:1 and 2:1 with modified heat treatment profile. The catalysts were characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, pore and particle size distribution, zeta potential and transmission electron microscopy. Electrocatalysts were integrated into membrane electrode assembly and evaluated by electrochemical methods. Electrochemical impedance spectroscopy in combination with modeling were used for estimation of proton conductivity of CCL and its oxygen diffusivity. It was found that all CCLs possess extremely high proton conductivity, which was demonstrated for the first time for these types of PGM-free catalysts. The observed ORR mechanism was predominantly 4e- due to peroxide/radicals scavenging effect of Mn.

impedance↗
DOE OSTI2025

Development of direct ink write radially graded alumina/zirconia

Functionally graded materials (FGMs) are of interest in multiple fields, yet many materials combinations are limited by coefficient of thermal expansion (CTE) mismatch. Here, a radially graded alumina/yttria-doped zirconia (Al 2 O 3 /8YZ) FGM is used to demonstrate processing strategies to mitigate CTE and sintering behavior differences between these oxides. FGM materials are especially sensitive to ink stability during printing, as all components (in this case, Al 2 O 3 and 8YZ) must be stabilized in the same dispersant or additive solution. Thus, this system is also ideal to demonstrate ink optimization best practices. Materials were characterized throughout processing to correlate the effects of common additives on both the ceramic particle suspensions and final sintered components. Aggregation observed in the initial additive-containing suspensions were present in the sintered component. The differences in sintering onset temperature and shrinkage rate resulted in internal stresses within the sintered component, which ultimately caused mechanical failure of the component under low stress. In conclusion, a processing strategy was recommended to mitigate the sintering behavior mismatch of alumina and 8 wt% yttria-stabilized zirconia.

Lamm, Benjamin W. [Oak Ridge National Laboratory (↗