Search NASA⌕ Search

SEARCH · Search NASA

Results for “solid−liquid interfaces”

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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Determination of the dispersion constant in a constrained vapor bubble thermosyphon

The isothermal profiles of the extended meniscus in a quartz cuvette were measured in a gravitational field using an image analyzing interferometer which is based on computer enhanced video microscopy of the naturally occurring interference fringes. The experimental results for heptane and pentane menisci were analyzed using the extended Young Laplace Equation. These isothermal results characterized the interfacial force field in-siru at the start of the heat transfer experiments by quantifying the dispersion constant, which is a function of the liquid-solid system and cleaning procedures. The experimentally obtained values of the disjoining pressure and the dispersion constants were compared to that predicted from the DLP theory and good agreements were obtained. The measurements are critical to the subsequent non-isothermal experiments because one of the major variables in the heat sink capability of the Constrained Vapor Bubble Thermosyphon, CVBT, is the dispersion constant. In all previous studies of micro heat pipes the value of the dispersion constant has been 'estimated'. One of the major advantages of the current glass cell is the ability to view the extended meniscus at all times. Experimentally, we find that the extended Young-Laplace Equation is an excellent model for the force field at the solid-liquid-vapor interfaces.

Dasgupta, Sunando↗
NASA NTRS1995

Interfacial Force Field Characterization in a Constrained Vapor Bubble Thermosyphon

Isothermal profiles of the extended meniscus in a quartz cuvette were measured in the earth's gravitational field using an image-analyzing interferometer that is based on computer-enhanced video microscopy of the naturally occurring interference fringes. These profiles are a function of the stress field. Experimentally, the augmented Young-Laplace equation is an excellent model for the force field at the solid-liquid-vapor interfaces for heptane and pentane menisci on quartz and tetradecane on SFL6. The effects of refractive indices of the solid and liquid on the measurement techniques were demonstrated. Experimentally obtained values of the disjoining pressure and dispersion constants were compared to those predicted from the Dzyaloshinskii - Lifshitz - Pilaevskii theory for an ideal surface and reasonable agreements were obtained. A parameter introduced gives a quantitative measurement of the closeness of the system to equilibrium. The nonequilibrium behavior of this parameter is also presented

DasGupta, Sunando↗
NASA NTRS1998

Growth of Bulk Single Crystals of Dicyanovinyl-Ansiole and its Derivatives for Nonlinear Optical Applications

Bulk single crystals of a series of thermally stable nonlinear optical organic materials, Dicyanovinyl-anisole (DIVA) and their methoxy derivatives, have been successfully grown using the Bridgman-Stockbarger technique. The growth conditions are chosen to be temperature gradient of 5 to 10 C/cm and lowering rate of 0.1 to 0.3 mm/h. Single crystals of DIVA and its derivatives, of 8 x 8 x 50 cu mm in size, have been grown while maintaining a flat solid-liquid growth interface.

Gebre, T.↗
NASA NTRS2016

Parallel Grand Canonical Monte Carlo (ParaGrandMC) Simulation Code

This report provides an overview of the Parallel Grand Canonical Monte Carlo (ParaGrandMC) simulation code. This is a highly scalable parallel FORTRAN code for simulating the thermodynamic evolution of metal alloy systems at the atomic level, and predicting the thermodynamic state, phase diagram, chemical composition and mechanical properties. The code is designed to simulate multi-component alloy systems, predict solid-state phase transformations such as austenite-martensite transformations, precipitate formation, recrystallization, capillary effects at interfaces, surface absorption, etc., which can aid the design of novel metallic alloys. While the software is mainly tailored for modeling metal alloys, it can also be used for other types of solid-state systems, and to some degree for liquid or gaseous systems, including multiphase systems forming solid-liquid-gas interfaces.

Vesselin I Yamakov↗
NASA NTRSDate not supplied

Crystal Growth in the SUBSA furnace in MSG: 2002 to 2022

In 2002, the investigation “Solidification Using a Baffle In Sealed Ampoules (SUBSA)” was the first investigation to utilize the Microgravity Science Glovebox (MSG) Facility on the International Space Station (ISS). The SUBSA furnace was designed for growth of indium antimonide. It features a transparent section, which allows a side view of the melt, the solid-liquid (SL) interface and the growing crystal. In 2002, four Te-doped and three Zn-doped InSb crystals were grown in microgravity. Subsequently, the SUBSA furnace was used in several materials science investigations, including growing the radiation detector materials, InI and Cs2LiYCl6:Ce from the melt and vapor phase (2017 to 2019) and “Brazing of Aluminum alloys in Space (BRAINS)”. A review of the SUBSA furnace features and parameters will be presented, including the design of the growth ampoules, charge preparation, and the procedures used to grow InSb (in 2002) and InI (in 2019).

Aleksandar Ostrogorsky↗
NASA NTRS2022

Parallel Grand-Canonical Monte Carlo (ParaGrandMC) User’s Manual Version 2.0

This manual describes the commands and command line options for the Parallel Grand Canonical Monte Carlo version 2.0 (ParaGrandMC.2.0) simulation code. This is a highly scalable parallel FORTRAN 2003 code for simulating the thermodynamic evolution of materials at the atomic level, and predicting their thermodynamic state, phase diagram, chemical composition and mechanical properties. The code is specifically designed to simulate multi-component alloy systems, predict solid-state phase transformations such as austenite-martensite transformations, precipitate formation, recrystallization, capillary effects at interfaces, surface absorption, etc., which can aid the design of novel metallic alloys. While the software is mainly tailored for modeling metal alloys, it can also be used for other types of solid-state systems, and to some degree for liquid or gaseous systems, including multiphase systems forming solid-liquid-gas interfaces. In addition to performing Monte Carlo (MC) simulations, the code can also perform Molecular Dynamics (MD) and Langevin Dynamics (LD) simulations, which can be combined and interchanged with MC for faster and more efficient system evolution. A detailed description of the MC part of the code is provided in the NASA ParaGrandMC report: NASA/CR–2016-219202; http://www.sti.nasa.gov.

High performance computing↗
NASA NTRS1987

Noncontact temperature pattern measuring device

This invention relates to a noncontact imagine pyrometer system for obtaining the true temperature image of a given substance in a contactless fashion without making assumptions about localized emissivity of the substance or the uniformity of the temperature distribution. Such a contactless temperature imaging system has particular application in the study and production of many materials where the physical contact required to make a conventional temperature measurement drastically effects or contaminates the physical process being observed. Two examples where accurate temperature profiles are of critical interest are: (1) the solid-liquid phase change interface in the production of electronic materials and (2) metastable materials in the undercooling region. The apparent novelty resides in the recognition that an active pyrometer system may be advantageously adapted to perform contactless temperature imaging so that an accurate temperature profile can be obtained.

Elleman, D. D.↗
NASA NTRS1999

Project Description and Publications List for UAH CMMR

This research combines a state of the art X-ray Transmission Microscope, XTM, with a specially designed x-ray transparent horizontal Bridgman furnace to image (with resolutions up to 3 micrometers) the solidification of metal alloys in real-time. The objective is to obtain real-time dynamic data to provide direct measure of the solute profile in the liquid, phase coalescence and growth in the liquid, and the detailed interface morphology (e,g., dendrites and cells) during solidification. We are also enhancing the XTM data with precise solid-liquid interfacial temperature and the thermal gradient measurement techniques, and working on the application of this technology to the study of the fundamentals of solidification in microgravity. Over the last several years we have successfully imaged in real-time: interfacial-morphologies, phase growth, coalescence, incorporation of phases into the growing interface, and the solute boundary layer in the liquid at the solid-liquid interface. We have also measured true local growth rates and can evaluate segregation structures in the solid. Interfacial undercoolings are being measured either with a special Seebeck furnace or with micro-thermocouple arrays we are developing. These later techniques are presently being incorporated with the XTM furnace. This last year emphasized the investigation of the solute layer in the melt during solidification. Methods were developed to quantify the solute concentrations using x-ray absorption and to compare to predictions from simulations. In addition, work is being completed on a brass-board portable XTM that incorporates a vertical Bridgman furnace.

Kaukler, William F.↗
NASA NTRS1998

Real-Time X-Ray Microscopy of Al-Cu Eutectic Solidification

Recent improvements in the resolution of the X-ray Transmission Microscope (XTM) for Solidification Studies provide microstructure feature detectability down to 5 micrometers during solidification. This presentation will show the recent results from observations made in real-time of the solid-liquid interfacial morphologies of the Al-CuAI2 eutectic alloy. Lamellar dimensions and spacings, transitions of morphology caused by growth rate changes, and eutectic grain structures are open to measurements. A unique vantage point viewing the face of the interface isotherm is possible for the first time with the XTM due to its infinite depth of field. A video of the solid-liquid interfaces seen in-situ and in real-time will be shown.

Kaukler, William F.↗
NASA NTRS1999

Thermophysical Property Measurements of Molten Semiconductors in 1-g and Reduced-g Condition

Understanding and controlling the formation kinetics of varieties of crystal imperfections such as point defects, non uniform distribution of doping atoms, and impurity atoms in growing crystals are very important. Theoretical (numerical) modeling of the crystal growth process is an essential step to achieving these objectives. In order to obtain reliable modeling results, input parameters, i.e. various thermophysical parameters, must be accurate. The importance of accurate thermophysical properties of semiconductors in crystal growth cannot be overly emphasized. The total hemispherical emissivity, for instance, has a dramatic impact on the thermal environment. It determines the radiative emission from the surface of the melt which determines to a large extent the profile of the solidified crystal. In order to understand the convection and the turbulence in a melt, viscosity becomes an important parameter. The liquid surface tension determines the shape of the liquid-atmosphere interface near the solid-liquid-atmosphere triple point. Currently used values for these parameters are rather inaccurate, and this program intends to provide more reliable measurements of these thermophysical properties. Thus, the objective of this program is in the accurate measurements of various thermophysical properties which can be reliably used in the modeling of various crystal growth processes. In this program, thermophysical properties of molten semiconductors, such as Si, Ge, Si-Ge, and InSb will be measured as a function of temperature using the High Temperature Electrostatic Levitator at JPL. Each material will be doped by different kinds of impurities at various doping levels. Thermophysical properties which will be measured include: density, thermal expansion coefficient, surface tension, viscosity, specific heat, hemispherical total emissivity, and perhaps electrical and thermal conductivities. Many molten semiconductors are chemically reactive with crucibles. As a result, these dispersed impurities in the melts tend to substantially modify the properties of pure semiconductors. Sample levitation done in a vacuum clearly helps maintain the sample purity. However, in the 1-g environment, all gravity caused effects such as convection, sedimentation and buoyancy are still present in the sample. In addition, large forces needed to levitate a sample in the presence of the gravity can cause additional flows in the melt. The use of the High Temperature Electrostatic Levitator (HTESL) for the present research is a recent development and little is known about the flows induced by the electrostatic forces. In this ground base program, we will define the limits of HTESL technology as various thermophysical properties of molten semiconductors are measured.

Rhim, Won-Kyu↗
NASA NTRS1992

Tribology of magnetic storage systems

The construction and the materials used in different magnetic storage devices are defined. The theories of friction and adhesion, interface temperatures, wear, and solid-liquid lubrication relevant to magnetic storage systems are presented. Experimental data are presented wherever possible to support the relevant theories advanced.

Bhushan, Bharat↗
NASA NTRS1972

Critical levitation loci for spheres on cryogenic fluids.

The conditions which allow a fluid to support a sphere having a higher specific gravity than its own are investigated. Three basic parameters which together define the maximum floating conditions are considered, including the Bond number, the wetting angle of the interface, and the ratio of solid-liquid specific gravities. The Bond number represents the ratio of buoyancy to surface tension forces. An analysis of the forces at the sphere-liquid interface is conducted to determine the optimum levitation loci, that is, the conditions permitting flotation of a maximum density sphere. Data for glycerine, carbon tetrachloride, and water spheres floating on a liquid nitrogen surface appear to be in good agreement with the analysis. Data for Teflon spheres on water also appear to be in agreement with the analytical results.

Hendricks, R. C.↗
NASA NTRS1999

The Micromechanics of the Moving Contact Line

A transient moving contact line is investigated experimentally. The dynamic interface shape between 20 and 800 microns from the contact line is compared with theory. A novel experiment is devised, in which the contact line is set into motion by electrically altering the solid-liquid surface tension gamma(sub SL). The contact line motion simulates that of spontaneous wetting along a vertical plate with a maximum capillary number Ca approx. = 4 x 10(exp -2). The images of the dynamic meniscus are analyzed as a funtion of Ca. For comparison, the steady-state hydrodynamic equation based on the creeping flow model in a wedge geometry and the three-region uniform perturbation expansion of Cox (1986) is adopted. The interface shape is well depicted by the uniform solutions for Ca <= 10(exp -3). However, for Ca > 10(exp -3), the uniform solution over-predicts the viscous bending. This over-prediction can be accounted for by modifying the slip coefficient within the intermediate solution. With this correction, the measured interface shape is seen to match the theoretical prediction for all capillary numbers. The amount of slip needed to fit the measurements does not scale with the capillary number.

Lichter, Seth↗
NASA NTRS2010

U.S. Materials Science on the International Space Station: Status and Plans

This viewgraph presentation reviews the current status and NASA plans for materials science on the International Space Station. The contents include: 1) Investigations Launched in 2009; 2) DECLIC in an EXPRESS rack; 3) Dynamical Selection of Three-Dimensional Interface Patterns in Directional Solidification (DSIP); 4) Materials Science Research Rack (MSRR); 5) Materials Science Laboratory; 6) Comparison of Structure and Segregation in Alloys Directionally Solidified in Terrestrial and Microgravity Environments (MICAST/CETSOL); 7) Coarsening in Solid Liquid Mixtures 2 Reflight (CSLM 2R); 8) Crystal Growth Investigations; 9) Levitator Investigations; 10) Quasi Crystalline Undercooled Alloys for Space Investigation (QUASI); 11) The Role of Convection and Growth Competition in Phase Selection in Microgravity (LODESTARS); 12) Planned Additional Investigations; 13) SETA; 14) METCOMP; and 15) Materials Science NRA.

Chiaramonte, Francis P.↗
NASA NTRS2004

Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment

Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of 7 km on 1) an ocean and 2) a layer of bedrock. Knowledge of the ionospheric contributions to the time delay of the low-frequency subsurface radar is shown to be important in obtaining accurate depth information.

Green, James L.↗
NASA NTRS1985

Modeling of convection phenomena in Bridgman-Stockbarger crystal growth

Thermal convection phenomena in a vertically oriented Bridgman-Stockbarger apparatus were modeled by computer simulations for different gravity conditions, ranging from earth conditions to extremely low gravity, approximate space conditions. The modeling results were obtained by the application of a state-of-the art, transient, multi-dimensional, completely densimetrically coupled, discrete-element computational model which was specifically developed for the simulation of flow, temperature, and species concentration conditions in two-phase (solid-liquid) systems. The computational model was applied to the simulation of the flow and the thermal conditions associated with the convection phenomena in a modified Germanium-Silicon charge enclosed in a stationary fused-silica ampoule. The results clearly indicated that the gravitational field strength influences the characteristics of the coherent vortical flow patterns, interface shape and position, maximum melt velocity, and interfacial normal temperature gradient.

Carlson, F. M.↗
NASA NTRS2005

Influence of Planetary Protection Guidelines on Waste Management Operations

Newly outlined missions in the Space Exploration Initiative include extended human habitation on Mars. During these missions, large amounts of waste materials will be generated in solid, liquid and gaseous form. Returning these wastes to Earth will be extremely costly, and will therefore likely remain on Mars. Untreated, these wastes are a reservoir of live/dead organisms and molecules considered to be "biomarkers" i.e., indicators of life). If released to the planetary surface, these materials can potentially confound exobiology experiments and disrupt Martian ecology indefinitely (if existent). Waste management systems must therefore be specifically designed to control release of problematic materials both during the active phase of the mission, and for any specified post-mission duration. To effectively develop waste management requirements for Mars missions, planetary protection guidelines must first be established. While previous policies for Apollo lunar missions exist, it is anticipated that the increased probability of finding evidence of life on Mars, as well as the lengthy mission durations will initially lead to more conservative planetary protection measures. To facilitate the development of overall requirements for both waste management and planetary protection for future missions, a workshop was conducted to identify how these two areas interface, and to establish a preliminary set of planetary protection guidelines that address waste management operations. This paper provides background regarding past and current planetary protection and waste management issues, and their interactions. A summary of the recommended planetary protection guidelines, anticipated ramifications and research needs for waste management system design for both forward (Mars) and backward (Earth) contamination is also provided.

Hogan, John A.↗
NASA NTRS1986

Shuttle waste management system design improvements and flight evaluation

The Space Shuttle waste management system has undergone a variety of design changes to improve performance and man-machine interface. These design improvements have resulted in more reliable operation and hygienic usage. Design enhancements include individual urinals, increased urine collection airflows, increased solids storage capacity, easier access to personal hygiene items, and additional wet trash stowage. The development and flight evaluation of these improvements are described herein. The Space Shuttle Orbiter has proved to be an invaluable test bed for development and in-flight evaluation of life support and habitability concepts which involve transport or separation of solids, liquids, and gases in a zero-g environment.

Winkler, H. Eugene↗