Search NASA⌕ Search

SEARCH · Search NASA

Results for “drying methods”

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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Growth of single crystals of organic salts with large second-order optical nonlinearities by solution processes for devices

Data obtained from the electric field induced second harmonic generation (EFISH) and Kurtz Powder Methods will be provided to MSFC for further refinement of their method. A theoretical model for predicting the second-order nonlinearities of organic salts is being worked on. Another task is the synthesis of a number of salts with various counterions. Several salts with promising SHG activities and new salts will be tested for the presence of two crystalline forms. The materials will be recrystallized from dry and wet solvents and compared for SHG efficiency. Salts that have a high SHG efficiency and no tendency to form hydrates will be documented. The synthesis of these materials are included in this report. A third task involves method to aid in the growth of large, high quality single crystals by solution processes. These crystals will be characterized for their applicability in the fabrication of devices that will be incorporated into optical computers in future programs. Single crystals of optimum quality may be obtained by crystal growth in low-gravity. The final task is the design of a temperature lowering single crystal growth apparatus for ground based work. At least one prototype will be built.

Leslie, Thomas M.↗
DOE OSTI2018

Water vapor exposure chamber for constant humidity and hydrogen and oxygen stable isotope composition

Rationale: Water vapor exposure experiments have applications for studying water physisorption and chemisorption hydration and hydroxylation reactions on a wide variety of material surfaces. The stable isotopes of hydrogen and oxygen in the water molecule are useful tracers of water exchange mechanisms and/or rates in such vapor exposure experiments. Methods: We designed and built a humidity chamber system that uses membrane-mediated liquid–vapor exchange of water followed by mixing with dry air to control the relative humidity of air and its δ 2 H and δ 18 O isotopic composition. We tested the stability and precision of the humidity and its isotopic composition on hourly to 90-day timescales. Results: The humidity chamber design reported here is capable of providing relative humidity control to within ±1%, and consistent δ 2 H and δ 18 O values of the water vapor that are similar to our cavity ringdown spectroscopy (CRDS) measurement precision (δ2H vap ± 0.7‰ and δ18O vap ± 0.24‰). We quantify the isotopic enrichment effects of Rayleigh distillation in the system and provide information on water reservoir sizes large enough to buffer isotopic enrichment effects to within measurement precision. Conclusions: The humidity chamber design reported here provides a means to create constant δ2H and δ18O values over the course of an exposure experiment. The design has applications to a wide range of studies of water sorption on material surfaces from foods and pharmaceuticals to geological materials.

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

Effect of surface hydroxyl groups on heat capacity of mesoporous silica

This paper quantifies the effect of surface hydroxyl groups on the effective specific and volumetric heat capacities of mesoporous silica. To achieve a wide range of structural diversity, mesoporous silica samples were synthesized by various methods, including (i) polymer-templated nanoparticle-based powders, (ii) polymer-templated sol-gel powders, and (iii) ambigel silica samples dried by solvent exchange at room temperature. Their effective specific heat capacity, specific surface area, and porosity were measured using differential scanning calorimetry and low-temperature nitrogen adsorption-desorption measurements. The experimentally measured specific heat capacity was larger than the conventional weight-fraction-weighted specific heat capacity of the air and silica constituents. The difference was attributed to the presence of OH groups in the large internal surface area. A thermodynamic model was developed based on surface energy considerations to account for the effect of surface OH groups on the specific and volumetric heat capacity. The model predictions fell within the experimental uncertainty.

Marszewski, Michal↗
DOE OSTI2021

Submicron Thickness Characterization of Poly-Si Thin Films on Textured Surfaces by X-Ray Diffraction for Minimizing Parasitic Absorption in Poly-Si/SiO2 Passivating Contact Cells

Poly-Si/SiO2 passivating contacts have shown great potential for industry-relevant next-generation solar cells. Previous work has demonstrated an improved Jsc from dry reactive ion etching in an SF6 environment, using front metal grids as a self-aligned mask. Here, we show an effective method to measure the front poly-Si thickness on an alkaline textured surface using X-ray diffraction. The calculated thicknesses are compared with cross-section SEM analysis and Quokka simulation. We show that by thinning the front poly-Si from 200 nm to 60 nm, Jsc increases by 2.4 mA/cm2, leading to an absolute efficiency gain of 1.73%. Finally, we discuss possible reasons for the premature loss of passivation before the removal of all poly-Si.

41 EE - Solar Energy Technologies Office (EE-4S)↗
DOE OSTI2024

Optimization of a High Pressure Turbine Blade and Sector-Based Annular Rig Design for Supercritical CO2 Power Cycle Representative Testing

Abstract As part of the ongoing research into the design of hardware for zero emission cycles, a first-stage high-pressure turbine (HPT) blade is optimized for a 300 MWe supercritical CO2 (sCO2) power cycle using the surrogate-assisted genetic algorithm optimizer in Numeca FINE/Design three-dimensional with objectives of increasing efficiency and decreasing heat load to the blade. Supercritical CO2 property tables are constructed from NIST REFPROP data for the condensable gas simulation in FINE/Turbo. A detailed mesh sensitivity study is performed for a baseline design to identify the proper-grid refinement and efficiently allocate resources for the optimization. Seventy design variables are selected for the initial population generation. Self-organizing maps are then used to focus the design variables on the most important ones affecting the objective functions. The optimization results in approximately 3000 three-dimensional Reynolds Averaged Navier Stokes simulations of different blade shapes with increases in efficiency of up to 0.85% and decreases in heat load of 14%. Families of blade shapes are identified for experimental testing in an annular rig at the Purdue Experimental Turbine Aerothermal Laboratory. A design to adapt the annular cascade for testing optimized geometries is introduced, which features eccentric radius sectors allowing for scaled-up geometries of sCO2 optimized blade profiles to be tested at design cycle representative conditions at high Reynolds numbers in dry air. Analysis into the effects of Reynolds number, working fluid, and geometric relations are presented to prove the efficacy of the test method.

Engineering↗
DOE OSTI2018

Neutron Measurements from Boron Carbide Addition to a Plutonium Waste Form

The Department of Energy (DOE) has identified the Dilute and Dispose approach as the preferred method for the disposition of surplus plutonium materials. Dilute and Dispose requires surplus plutonium to be converted to an oxide product and then dry blended with a multi-component adulterant mixture to reduce the Safeguards and Security attractiveness level of the materials. The resulting product will be discarded in a geologic repository at the Waste Isolation Pilot Plant (WIPP).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Sol-Gel Based Nanoparticles for 3D Printing of Optical Glass

Additive manufacturing also known as 3D printing provides an innovative way to produce gradient index (GRIN) lens and other high-performance optics. Novel inks for direct ink write (DIW) 3D printed optical glass have been reported; however, the refractive index has never surpassed a value of 1.48. Here, we report a ternary formulation of core-shell SiO 2 nanoparticles coated with a TiO 2 shell and GeO 2 nanoparticles that can be used as a feedstock for DIW lenses. Printable titanium-germanium-silica inks were prepared from colloidal sol-gel feed stocks to produce shear-thinning inks for DIW. The inks were dried and sintered following an optimized heat treatment to remove organic material and produce a transparent and void-free monolith. Through this method, we found that these lenses are transparent at dopant concentrations of 7 mol% TiO 2 and 14 mol% GeO 2 . With higher dopant concentrations of germanium and titanium, these lenses subsequently have a refractive index of 1.52. Moreover, these inks share the same viscoelastic properties as previous shear thinning DIW inks, allowing these inks to be 3D printed.

36 MATERIALS SCIENCE↗
DOE OSTI2020

EBS Task Force: Task 9/FEBEX Modeling Final Report: Thermo-Hydrological Modeling with PFLOTRAN

This report outlines Sandia National Laboratories modeling studies applied to Stage 1 and Stage 2 of the Full-scale Engineered Barriers Experiment in Crystalline Host Rock (FEBEX) in situ test for the SKB EBS Task Force Task 9. The FEBEX test was a full-scale test conducted over ~18 years at the Grimsel, Switzerland Underground Research Laboratory (URL) managed by NAGRA. It involved emplacing simulated waste packages, in the form of welded cylindrical heaters, inside a tunnel in crystalline granitic rock and surrounded by a bentonite barrier and cement plug. Sensors emplaced within the bentonite monitored the wetting-up, heating, and drying out of the bentonite barrier, and the large resulting data set provides an excellent opportunity for validation of multiphysics Thermal-Hydrological (TH), Thermal-Hydrologic-Chemical (THC), and Thermal-Hydrological-Mechanical (THM) modeling approaches for underground nuclear waste storage and the performance of engineered bentonite barriers. The present status of the EBS Task Force is finalizing Task 9, which follows years of modeling studies of the FEBEX test, by many notable modeling teams (Gens et al., 2009; Sanchez et al. 2010; 2012; Samper et al., 2018). These modeling studies generally use two-dimensional axisymmetric meshes, ignoring threedimensional effects, gravity and asymmetric wetting and dry out of the bentonite engineered barrier. This study investigates these effects with use of the PFLOTRAN THC code with massively parallel computational methods in modeling FEBEX Stage 1 and Stage 2 results. The PFLOTRAN numerical code is an open source, state-of-the-art, massively parallel subsurface flow and reactive transport code operating in a high-performance computing environment (Hammond et al., 2014). Section 2 describes the applied partial differential equations describing mass, momentum and energy balance used in this study, considerations derived by assuming phase equilibrium between gas and liquid phases, constitutive equations for granite, cement plug, and bentonite domains, and specific approaches for use inthe PFLOTRAN code. Section 3 describes the geometry, meshing, and model set-up. Section 4 describes modeling results, Section 5 compares modeling results to field testing data, and Section 6 gives conclusions. The Appendix provides detailed information required by the EBSTask Force for final reporting.

42 ENGINEERING↗
NASA NTRS1984

Method for the preparation of thin-skinned asymmetric reverse osmosis membranes and products thereof

A method for preparing water insoluble asymmetric membranes from water soluble polymers is discussed. The process involves casting a film of the polymer, partially drying it, and then contacting it with a concentrated solution of a transition metal salt. The transition metal ions render the polymer insoluable and are believed to form a complex with it. Optionally, the polymer is crosslinked with heat or radiation. The most preferred polymer is poly(vinyl alcohol). The most preferred complexing salt is copper sulfate. The process and the metal ion linked membranes are discussed. The membranes are reverse osmosis membranes.

Wydeven, T. J.↗
NASA NTRS2017

Spacecraft Mission Design for the Mitigation of the 2017 PDC Hypothetical Asteroid Threat

This paper presents a detailed mission design analysis results for the 2017 Planetary Defense Conference (PDC) Hypothetical Asteroid Impact Scenario, documented at https:cneos.jpl.nasa.govpdcspdc17. The mission design includes campaigns for both reconnaissance (flyby or rendezvous) of the asteroid (to characterize it and the nature of the threat it poses to Earth) and mitigation of the asteroid, via kinetic impactor deflection, nuclear explosive device (NED) deflection, or NED disruption. Relevant scenario parameters are varied to assess the sensitivity of the design outcome, such as asteroid bulk density, asteroid diameter, momentum enhancement factor, spacecraft launch vehicle, and mitigation system type. Different trajectory types are evaluated in the mission design process from purely ballistic to those involving optimal midcourse maneuvers, planetary gravity assists, and/or low-thrust solar electric propulsion. The trajectory optimization is targeted around peak deflection points that were found through a novel linear numerical technique method. The optimization process includes constrain parameters, such as Earth departure date, launch declination, spacecraft, asteroid relative velocity and solar phase angle, spacecraft dry mass, minimum/maximum spacecraft distances from Sun and Earth, and Earth-spacecraft communications line of sight. Results show that one of the best options for the 2017 PDC deflection is solar electric propelled rendezvous mission with a single spacecraft using NED for the deflection.

Barbee, Brent W.↗
DOE OSTI2021

Methods and systems for 3D printing with powders

A method of printing a three dimensional article (201) can include forming a bottom layer of the three dimensional article (201) by spraying a dry build material powder (210) onto a build platform (230) while heating the dry build material powder (210). The dry build material powder (210) can include metal or ceramic particles mixed with a polymeric binder having a softening point temperature. The dry build material powder (210) can be heated to a temperature above the softening point temperature such that the dry build material powder (210) adheres to the build platform (230). Subsequent layers can be formed by spraying dry build material powder (210) onto a lower layer while heating the dry build material powder (210) such that the dry build material powder (210) adheres to the lower layer.

Fang, Zhigang Zak↗
DOE OSTI2022

Superomniphobic coatings and methods of preparation

A composition useful for producing a superomniphobic coating on a substrate, the composition comprising a colloidal suspension of a fluorinated siloxane in a non-silicon-containing fluorinated solvent. In some embodiments, the composition further comprises particles of a hydrophobized metal oxide, e.g., silicon oxide, wherein the hydrophobized metal oxide may be fluorinated. In some embodiments, the composition further comprises a non-silicon-containing fluorinated polymer. The invention is also directed to methods for making the above composition. The invention is also directed to methods for using the above-described composition for rendering a substrate superomniphobic. The aforesaid method comprises depositing a liquid coating solution onto a substrate to form a coated substrate, followed by subjecting the coated substrate to a drying step to remove a liquid phase of the liquid coating solution, wherein the liquid coating solution comprises a colloidal suspension of a fluorinated siloxane in a non-silicon-containing fluorinated solvent.

Lewis, Linda P.↗
DOE OSTI2015

Creating periodic local strain in monolayer graphene with nanopillars patterned by self-assembled block copolymer

A simple and viable method was developed to produce biaxial strain in monolayer graphene on an array of SiO{sub 2} nanopillars. The array of SiO{sub 2} nanopillars (1 cm{sup 2} in area, 80 nm in height, and 40 nm in pitch) was fabricated by employing self-assembled block copolymer through simple dry etching and deposition processes. According to high resolution micro-Raman spectroscopy and atomic force microscopy analyses, 0.9% of maximum biaxial tensile strain and 0.17% of averaged biaxial tensile strain in graphene were created. This technique provides a simple and viable method to form biaxial tensile strain in graphene and offers a practical platform for future studies in graphene strain engineering.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Facile fabrication of graphene composite microwires via drying-induced size reduction of hydrogel filaments

Graphene based electrical conductors are under consideration for numerous applications in energy storage, energy conversion devices, electronics and sensors. Here, we report a facile and versatile method for fabrication of graphene based composite microwires ranging from ~20 to 250 μm in diameter via size reduction during dehydration of extruded larger diameter graphene oxide-loaded agarose hydrogel fibers. The graphene oxide is effectively reduced to graphene by chemical and thermal treatment. Here, after dehydration and reduction, the resulting graphene composite microwires exhibit high electrical conductivities of up to 1.8 S m –1 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

An alternative solid-state method to prepare pyrochlore-free KTaO{sub 3} at low temperature

Perovskite-type KTaO{sub 3} powder was synthesized by an alternative solid-state method at low temperature. Stoichiometric ammonium tantalum hydroxide, K{sub 2}C{sub 2}O{sub 4} and KF were mixed in water and then dried at room temperature. The crude product was formed by calcining the dried mixture at different temperatures. Pyrochlore-free KTaO{sub 3} powder was successfully synthesized after treating the crude product with water. KF plays an important role to inhibit the formation of pyrochlore K{sub 2}Ta{sub 2}O{sub 6} during the calcination process of ammonium tantalum hydroxide/K{sub 2}C{sub 2}O{sub 4}/KF mixture. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, UV-vis diffuse reflectance (UV-vis) spectroscopy and thermogravimetric (TG) analysis were used to characterize the precursor compound and as-prepared samples. XRD results show that pyrochlore-free KTaO{sub 3} powder can be obtained at 600 deg. C. SEM results reveal that the as-prepared products are agglomerated and each of the agglomerations consists of many small grains with 10-30 nm in diameter. - Graphical abstract: Pyrochlore-free KTaO{sub 3} powder was prepared at 600 deg. C using tantalum hydroxide/K{sub 2}C{sub 2}O{sub 4}/KF raw materials. Pyrochlore K{sub 2}Ta{sub 2}O{sub 6} and perovskite KTaO{sub 3} coexist at 600 deg. C using tantalum hydroxide/K{sub 2}C{sub 2}O{sub 4} raw materials. Highlights: > In-situ degradation of TaO{sub x}(OH){sub 5-x}(NH{sub 4}){sub x}, K{sub 2}C{sub 2}O{sub 4} and KF promotes the reaction. > Synthesis of KTaO{sub 3} displayed a two-step reaction path with the intermediate formation of K{sub 2}TaO{sub 3}F. > Formation of intermediate K{sub 2}TaO{sub 3}F benefits to prepare pyrochlore-free KTaO{sub 3} at low temperature. > Pyrochlore-free KTaO{sub 3} is prepared at 600 deg. C, which is the lowest temperature reported so far by hard chemistry method. > Synthetic method is a facile, rapid, low price and environment friendly route.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2014

On Characterizing Particle Shape

It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.

Ennis, Bryan J.↗
NASA NTRS1976

Abiotic origin of biopolymers

A variety of methods have been investigated in different laboratories for the polymerization of amino acids and nucleotides under abiotic conditions. They include (1) thermal polymerization; (2) direct polymerization of certain amino acid nitriles, amides, or esters; (3) polymerization using polyphosphate esters; (4) polymerization under aqueous or drying conditions at moderate temperatures using a variety of simple catalysts or condensing agents like cyanamide, dicyandiamide, or imidazole; and (5) polymerization under similar mild conditions but employing activated monomers or abiotically synthesized high-energy compounds such as adenosine 5'-triphosphate (ATP). The role and significance of these methods for the synthesis of oligopeptides and oligonucleotides under possible primitive-earth conditions is evaluated. It is concluded that the more recent approach involving chemical processes similar to those used by contemporary living organisms appears to offer a reasonable solution to the prebiotic synthesis of these biopolymers.

Oro, J.↗
DOE OSTI2022

Describing the Influence of Ball-milling on the Amorphization of Flubendazole Using the PDF and RMC Methods with X-ray Powder Diffraction Data

Flubendazole (FBZ) is a poorly water-soluble drug, and different methodologies have been proposed to improve its oral bioavailability. Obtaining the amorphous drug phase is an alternative to improve its water solubility. Several techniques for drug amorphization, such as spray drying, lyophilization, melt quenching, solvent-evaporation, and ball milling, can yield various types of structural disorder and possibly render variations in physicochemical properties. Herein, we focus on evaluating the influence of the ball-milling process on the amorphization of FBZ. The characterization of the average global and local structures before, during, and after the milling process is described by sequential Rietveld refinements, pair distribution function analysis, and the Reverse Monte Carlo method. In conclusion, we show that preserving the local structure (nearest molecules) can be responsible for avoiding the fast structure recrystallization commonly observed when using the solvent-evaporation process for the studied drug.

60 APPLIED LIFE SCIENCES↗