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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Effects of Al:Si and (Al + Na):Si ratios on the properties of the international simple glass, part I: Physical properties

Understanding composition-structure-property relationships of high-alumina nuclear waste glasses are important for vitrification of nuclear waste at the Hanford Site. Two series of glasses were designed, one with varying Al:Si ratios and the other with (Al+Na):Si ratios based on the International Simple Glass (ISG, a simplified nuclear waste model glass), with Al2O3 ranging from 0 to 23 mol % (0 to 32 wt. %). The glasses were synthesized and characterized using electron probe microanalysis, X-ray photoelectron spectroscopy, small angle X-ray scattering, high temperature oxide melt solution calorimetry, and infrared spectroscopy. Glasses were crystal free, and the lowest Na2O and Al2O3 glass formed an immiscible glass phase. Evolution of various properties - glass transition temperature, percentage of 4-coordinated B, enthalpy of glass formation - and infrared spectroscopy results indicate that structural effects differ based on the glass series.

Nuclear Waste Glass↗
DOE OSTI2020

Tank 50H Mixing Pump Run Time Reassessment

Tank 50H is required to operate a single rotating standard slurry pump for 4.5 hours prior to transfers to the Salt Solution Receipt Tanks (SSRTs) in the Saltstone Production Facility (SPF). This mixing time is required to adequately mix miscible and immiscible liquids within Tank 50H and meet the Saltstone Waste Acceptance Criteria (WAC). The miscible liquids are aqueous solutions of dissolved salts, while the immiscible liquids include organic droplets such as Isopar® L. To support the accelerated salt processing rates from the Salt Waste Processing Facility (SWPF), a desire to reduce the transfer time of Decontaminated Salt Solution (DSS) downstream of SWPF was identified. This document describes the analysis performed to reassess the technical basis for the 4.5 hour mixing requirement for Tank 50H.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Self-Assembly and Phase Separation for Transport: A brief argument for the continued exploration of liquid crystal flows and electrodeposition in micro-gravity

Phase separation, interfacial tension gradients, and molecular self-assembly are all phenomena frequently observed when manipulating soft condensed matter systems on Earth. Depending on the system these processes can also be quite predictable. For instance, on Earth water droplets placed on hydrophobic surfaces will have contact angles > 90° with limited spread, contrary to their wetting behavior on hydrophilic surfaces. However, in an environment that is in a constant state of free-fall, where the gravitational field is reduced by 10%, such as on the International Space Station (ISS), buoyancy and its effect on fluid convection also become negligible. Fluid flow and phase behavior become less predictable. Thus, continuing the prior example, even if water droplets still remain in contact with a surface in microgravity (µg), the interface between the air and droplets will still remain significantly curved, appearing almost as if they were placed over completely nonwetting surfaces (Fig. 1a). Moreover, the negligible opposing buoyant force would also mean that if immiscible liquid droplets of a less dense character, or air bubbles even (Fig. 1b), were to be suspended within a larger water drop, these immiscible droplets or air bubbles would not migrate toward any one direction unless either artificially propelled by an external force or internal reaction inducing flow.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Numerical Modeling of CO2 Sequestration within a Five-Spot Well Pattern in the Morrow B Sandstone of the Farnsworth Hydrocarbon Field: Comparison of the TOUGHREACT, STOMP-EOR, and GEM Simulators

The objectives of this study were (1) to assess the fate and impact of CO2 injected into the Morrow B Sandstone in the Farnsworth Unit (FWU) through numerical non-isothermal reactive transport modeling, and (2) to compare the performance of three major reactive solute transport simulators, TOUGHREACT, STOMP-EOR, and GEM, under the same input conditions. The models were based on a quarter of a five-spot well pattern where CO2 was injected on a water-alternating-gas schedule for the first 25 years of the 1000 year simulation. The reservoir pore fluid consisted of water with or without petroleum. The results of the models have numerous broad similarities, such as the pattern of reservoir cooling caused by the injected fluids, a large initial pH drop followed by gradual pH neutralization, the long-term persistence of an immiscible CO2 gas phase, the continuous dissolution of calcite, very small decreases in porosity, and the increasing importance over time of carbonate mineral CO2 sequestration. The models differed in their predicted fluid pressure evolutions; amounts of mineral precipitation and dissolution; and distribution of CO2 among immiscible gas, petroleum, formation water, and carbonate minerals. The results of the study show the usefulness of numerical simulations in identifying broad patterns of behavior associated with CO2 injection, but also point to significant uncertainties in the numerical values of many model output parameters.

STOMP↗
DOE OSTI2024

Heterogeneous Morphologies and Hardness of Co-Sputtered Thin Films of Concentrated Cu-Mo-W Alloys

Heterogeneous microstructures in Cu-Mo-W alloy thin films formed by magnetron co-sputtering immiscible elements with concentrated compositions are characterized using scanning transmission electron microscopy (STEM) and nanoindentation. In this work, we modified the phase separated structure of a Cu-Mo immiscible system by adding W, which impedes surface diffusion during film growth. The heterogeneous microstructures in the Cu-Mo-W ternary system exhibited bicontinuous matrices and agglomerates composed of Mo(W)-rich phase. This is unique, as these are the slower-diffusing species, contrasting past reports of binary Cu-Mo thin films that exhibited Cu-rich agglomerates. The bicontinuous matrices comprised of Cu-rich and Mo(W)-rich phases exhibited bilayer thicknesses of less than 5 nm. The hardness of these thin films measured using nanoindentation is reported and compared to similar multilayers and nanocomposites in binary systems.

36 MATERIALS SCIENCE↗
NASA NTRS1971

Test and evaluation of Apollo 14 composite casting demonstration specimens 6, 9, and 12, phase 1

Flight and control specimens 6, 9, and 12 from the Apollo 14 composite casting demonstration were evaluated with respect to the degree of dispersion achieved for mixtures of immiscible materials under one-gravity and low gravity environments. The flight and control capsules 6, 9, and 12 contained paraffin and sodium acetate; paraffin, sodium acetate and argon; and paraffin, sodium acetate and 100 micrometer diameter tungsten microspheres, respectively. The evaluation and documentation utilized photographic and microstructure examinations, density measurements, and droplet size and distribution determinations. In addition, theoretical analyses were performed in order to aid in the understanding of the fluid behavior of the specimens during processing and subsequent solidification. A comparison of evaluated data with the theoretical analyses reveals that although the immiscible materials were uniquely dispersed in a low gravity environment, nonuniform dispersions were obtained primarily due to insufficient initial mixing and an essentially unidirectional thermal gradient during cooldown.

Reger, J. L.↗
NASA NTRS1974

The stability of liquid dispersions in low gravity

The stability of three different dispersions of oil and water prepared on Skylab 4 is compared with the same dispersions made on earth. The stability of the emulsions has been studied by two independent optical techniques. An analysis of the data indicates that all the investigated emulsions were stable over a period of 10 hr, whereas the fluids separated completely on earth in 10 sec. This experiment indicates that the rate of coalescence in low gravity is at least 3 millionths times that on earth. A knowledge of the coalescence rate in low gravity is important in the solidification of immiscible alloys in space. The parameters obtained for this experiment are compared with those of liquid metals to determine if the same stability could be achieved with immiscible alloys.

Lacy, L. L.↗
NASA NTRS1975

Morphology and composition of chalcopyrite, chromite, Cu, Ni-Fe, pentlandite, and troilite in vugs of 76015 and 76215

Vugs from 76015 and 76215 are lined with euhedral crystals of plagioclase, pyroxene, ilmenite, Ni-Fe, and troilite. Smaller crystals of chromite, pentlandite, and chalcopyrite occur on the surface of the troilite in 76015. Wire Cu and dendritic-metallic Cu occurs with metallic Ni-Fe and troilite in some vugs of 76215. Troilite in both samples may have crystallized from an immiscible sulfide liquid. With falling temperature, chalcopyrite, and pentlandite may have exsolved from the troilite in 76015. By contrast, metallic Cu may have formed in 76215 by thermal breakdown of a bornite, troilite, and Ni-Fe assemblage which originally crystallized from a low-Ni immiscible sulfide liquid.

Carter, J. L.↗
NASA NTRS1979

Magnetite-sulfide-metal complexes in the Allende meteorite

A model of liquid immiscibility is presented that seemingly accounts for the sulfide-oxide-metal complexes that are present in olivine-rich chondrules in the Allende meteorite. The four major assemblages that are identified are: (1) magnetite + Ni-Fe metal; (2) magnetite + troilite + Ni-Fe metal; (3) magnetite + troilite + pentlandite + Ni-Fe metal; and (4) troilite + or - pentlandite. Specific attention is focused on oxide-metal associations and experimental data confirm earlier suggestions that magnetite results from the oxidation of an initially high-Fe-content metal alloy. Oxidation decreases the modal abundance of the Fe metal and this is accompanied by substantial increases in Ni contents which reach a maximum of approximately 70 wt % Ni. The proposed oxidation mechanism is entirely consistent with condensation of Fe-metal + olivine (Fa5) that subsequently reequilibrated at lower temperatures. Although the sulfide constituents could also have formed by the reaction of Fe-Ni metal + gaseous H2S, sulfide immiscibility under increased conditions of partial O2 pressure is the preferred process.

Haggerty, S. E.↗
NASA NTRS1980

The role of P2O5 in silicate melts

Phase equilibria data in the systems SiO2-P2O5, P2O5-M(x)O(y), and P2O5-M(x)O(y)-SiO2 are employed in conjunction with chromatographic and spectral data to investigate the role of P2O5 in silicate melts. P2O5 depolymerizes pure SiO2 melts by entering the network as a four-fold coordinated cation, but polymerizes melts in which an additional metal cation other than silicon is present. In this complex system P2O5 acts to increase phase separation by further enrichment of the high charge density cations Ti, Fe, Mg, Mn, Ca, in the ferrobasaltic liquid. The dual behavior of P2O5 is explained in a model which requires complexing of phosphate anions and metal cations in the melt. This interaction destroys Si-O-M-O-Si bonds polymerizing the melt. The higher concentration of Si-O-M-O-Si bond complexes in immiscible ferrobasaltic liquids relative to their conjugate immiscible granite liquids explains the partitioning of P2O5 into the ferrobasaltic liquid.

Ryerson, F. J.↗
NASA NTRS1982

Solidification phenomena of binary organic mixtures

The coalescence rates and motion of liquid bubbles in binary organic mixtures were studied. Several factors such as temperature gradient, composition gradient, interfacial tension, and densities of the two phases play important roles in separation of phases of immiscible liquids. An attempt was made to study the effect of initial compositions on separation rates of well-dispersed organic mixtures at different temperatures and, ultimately, on the homogeneity of solidification of the immiscible binary organic liquids. These organic mixtures serve as models for metallic pseudo binary systems under study. Two specific systems were investigated: ethyl salicylate - diethyl glycol and succinonitrile - water.

Chang, K.↗
NASA NTRS1982

Anomalous phase separation behavior of gel-derived soda-silica glasses

The effects of retained bound hydroxyl groups on amorphous immiscibility behavior and on the kinetics of phase separation were studied in glasses containing from 10 to 19 percent sodium oxide preparaed by the gel process. Differences in behavior as functions of preliminary thermal treatment of the gel precursor and of melting conditions were studied, employing IR spectroscopy, SAXS and WAXD to monitor the variation in glass microstructure. Both the initial gel treatment and the OH concentration in the prepared glasses were found to affect the immiscibility temperatures, and the magnitude of the maximum temperature increase was also a function of the sodium oxide concentration. It is suggested that the variation in thermodynamic behavior may be caused by the structural arrangement attained by the OH groups during the gel condensation process, which in turn affects the extent of hydrogen bonding to nonbridging oxygen ions.

Neilson, G. F.↗
NASA NTRS1984

Critical point wetting drop tower experiment

Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

Kaukler, W. F.↗
NASA NTRS1985

Effect of Undercooling and Modified Microstructure on the Physical Properties of Material Synthesized in the Drop Tube and Drop Tower

The effects of undercooling and modified microstructure on the physical properties of synthesized materials were investigated. The objectives of this program are: (1) to determine the possible existence of metastable phases and novel physical processes on material prepared in a microgravity environment; and (2) to investigate the feasibility of fabricating advanced electronic devices using material with microstructures obtainable in a microgravity environment. The specific alloys and compounds under study are Au-Ge and immiscible alloys Nb-Ge compounds, and Ga-Bi immiscible alloys, and Ba-Pb-Bi-O. The superconducting and normal state transport properties of the materials under different pressures and in different magnetic fields were determined. The simultaneous study on the physical properties and the microstructure of material will provide information about the potential applications of materials processed in a microgravity environment.

Chu, C. W.↗
NASA NTRS1985

Advanced Optical Measurement Techniques

This research analyzes four areas: (1) Improved Techniques for Optical Measurement; (2) KC-135 Low Gravity Simulation Flight Preparation; (3) In-Line Holographic Microscopy; and (4) Holographic Optical Schlieren System (HOSS). The first task provides for laboratory breadboarding of advanced optical measurement techniques which appear promising for use in Material Processing System (MPS) flight experiments. A laboratory schlieren system has been constructed which simulates a similar optical system on the Fluids Experiment System (FES) which is to be flown on Spacelab 3. The second task allows improved optical systems and breadboards to be built for experiments and hardware tests on the KC-135 aircraft. A new, more stable Mach-Zehnder interferometer has been developed and components have been ordered. The third task is concerned with improvements on the optical system being used to study immiscible fluids. Experiments studying the dynamics of nucleation and the separation of immiscible fluids have been conducted. The four task involves building breadboard reconstruction systems for holograms taken in the HOSS. The HOSS is an early prototype of the Fluids Experiments System (FES) which is scheduled to fly on Spacelab 3.

Owen, R. B.↗
NASA NTRS1988

Influence of gravity level and interfacial energies on dispersion-forming tendencies in hypermonotectic Cu-Pb-Al alloys

Results on the nondirectional solidification of several hypermonotectic Cu-Pb-Al alloys were obtained aboard NASA's KC-135 zero-gravity aircraft in order to determine the influence of interfacial energies and gravity levels on dispersion-forming tendencies. The Al content was systematially varied in the alloys. The dispersion-forming ability is correlated with gravity level during solidification, the interfacial energy between the immiscible phases, and the tendency for the minority immiscible phase to wet the walls of the crucible.

Andrews, J. B.↗
NASA NTRS1988

Equilibrium shapes of rotating spheroids and drop shape oscillations

Recent work on the equilibrium shapes of a rotating spheroid and drop shape oscillations is reviewed. The related theoretical aspects of the equilibrium shapes of a rotating drop, the stability, shape oscillations, gravitational forces, and drop fission are examined. Experimental findings on figures of a rotating drop in an immiscible system, drop oscillations in an immiscible system, oscillations of a rotating drop, compound drop oscillations, and drop dynamics in space are addressed.

Wang, Taylor G.↗
NASA NTRS1990

Thermal buoyancy and Marangoni convection in a two fluid layered system - A numerical study

Thermal buoyancy and surface tension driven convection is numerically investigated in a system with two, immiscible fluids. The geometry investigated, has an open cavity configuration with the lighter fluid situated on top of the heavier fluid, forming a stable layered system. The upper fluid meniscus and the interface are assumed to be flat and undeformable in the calculations. The governing equations and boundary/interface conditions are solved by a control volume based finite difference scheme for two pairs of immiscible fluids; the water-hexadecane system and a so called generic system. The steady state calculations show, that dramatically different flows are predicted when the interfacial tension effects are included or excluded from the system model. These differences are particularly appreciable in surface tension dominated flows, that are typical of microgravity situations. Complex flow patterns, with induced secondary flows are noticed in both the fluids. In general, the overall system heat transfer is found to increase with increases in the thermal buoyancy and surface tension effects, but the behavior of the system flow and thermal fields is not easy to characterize, when different combinations of these forces are considered.

Ramachandran, N.↗