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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 1,279 records · Page 71
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Advanced Material Developments with Laser Engineered Net Shaping

The Laser Engineered Net Shaping (LENS(Trademark)) process is a new technology to fabricate three-dimensional metallic components directly from CAD solid models. It directly fabricates metal hardware by injecting the metal powder of choice into the focal point of a 700W Nd:Yag laser as it traces the perimeter and fills of a part. The Rapid Prototype Laboratory at Marshall Space Flight Center is currently operating a OPTOMEC 750 LENS machine in evaluation experiments involving integration of this technology into various manufacturing processes associated with aerospace applications. This paper will cover our research finding about properties of samples created from Inconel 718 & SS316 using this process versus the same materials in cast & wrought conditions.

Williams, Glenn A.↗
DOE OSTI2017

Modeling variability in porescale multiphase flow experiments

Microfluidic devices and porescale numerical models are commonly used to study multiphase flow in biological, geological, and engineered porous materials. In this work, we perform a set of drainage and imbibition experiments in six identical microfluidic cells to study the reproducibility of multiphase flow experiments. We observe significant variations in the experimental results, which are smaller during the drainage stage and larger during the imbibition stage. We demonstrate that these variations are due to sub-porescale geometry differences in microcells (because of manufacturing defects) and variations in the boundary condition (i.e.,fluctuations in the injection rate inherent to syringe pumps). Computational simulations are conducted using commercial software STAR-CCM+, both with constant and randomly varying injection rate. Stochastic simulations are able to capture variability in the experiments associated with the varying pump injection rate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Harnessing nanoscale densification for controlling gas selectivity in flexible zeolitic imidazolate frameworks

Flexible metal-organic frameworks (MOFs) are promising for gas separation due to their molecular recognition capabilities. However, gate-opening behavior in certain flexible MOFs can reduce gas selectivity, enabling simultaneous adsorption of multiple gases. We introduce a binder-free, pressure-free densification process to enhance gas selectivity in flexible zeolitic imidazolate frameworks (ZIF-7 and ZIF-9) by optimizing nanoparticle packing. Unlike powders, the densified ZIF-7 and ZIF-9 retain rhombohedral crystal structures after solvent removal, confirmed via synchrotron powder X-ray diffraction. This process modifies adsorption behavior by introducing a diffusion barrier, enabling diffusivity-driven kinetic separation and enhanced CO2/hydrocarbon selectivity. At 0.5 bar, ZIF-7 mono shows 2×, 4×, and 9.5× higher CO 2 selectivity over C 2 H 2 , C 2 H 4 , and C 2 H 6 , respectively, versus ZIF-7 pwd . ZIF-9 mono similarly shows 6.5×, 3×, and 39× improvements over ZIF-9 pwd . Both monoliths outperform powders in ternary gas mixtures. This study provides a novel strategy to control gate opening and enhance gas selectivity in flexible MOFs for practical separation applications.

CO2/hydrocarbon separation↗
DOE OSTI2020

Degradation of solid oxide electrolysis cells: Phenomena, mechanisms, and emerging mitigation strategies—A review

Solid oxide electrolysis cell (SOEC) is a promising electrochemical device with high efficiency for energy storage and conversion. However, the degradation of SOEC is a significant barrier to commercial viability. In this review article, the typical degradation phenomena of SOEC are summarized, with great attention into the anodes/oxygen electrodes, including the commonly used and newly developed anode materials. Meanwhile, mechanistic investigations on the electrode/electrolyte interfaces are provided to unveil how the intrinsic factor, oxygen partial pressure , and the electrochemical operation conditions, affect the interfacial stability of SOEC. At last, this paper also presents some emerging mitigation strategies to circumvent long-term degradation, which include novel infiltration method, development of new anode materials and engineering of the microstructure.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Study of the capacitance technique for measuring high-temperature blade tip clearance on ceramic rotors

Higher operating temperatures required for increased engine efficiency can be achieved by using ceramic materials for engine components. Ceramic turbine rotors are subject to the same limitations with regard to gas path efficiency as their superalloy predecessors. In this study, a modified frequency-modulation system is proposed for the measurement of blade tip clearance on ceramic rotors. It is expected to operate up to 1370 C (2500 F), the working temperature of present engines with ceramic turbine rotors. The design of the system addresses two special problems associated with nonmetallic blades: the capacitance is less than that of a metal blade and the effects of temperature may introduce uncertainty with regard to the blade tip material composition. To increase capacitance and stabilize the measurement, a small portion of the rotor is modified by the application of 5-micron-thick platinum films. The platinum surfaces on the probe electrodes and rotor that are exposed to the high-velocity gas stream are coated with an additional 10-micron-thick protective ceramic topcoat. A finite-element method is applied to calculate the capacitance as a function of clearance.

Barranger, John P.↗
DOE OSTI2018

Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies

Many forward-looking clean-energy technologies hinge on the development of scalable and efficient membrane-based separations. Ongoing investment in the basic research of microporous materials is beginning to pay dividends in membrane technology maturation. Specifically, improvements in membrane selectivity, permeability, and durability are being leveraged for more efficient carbon capture, desalination, and energy storage, and the market adoption of membranes in those areas appears to be on the horizon. Herein, an overview of the microporous materials chemistry driving advanced membrane development, the clean-energy separations employing them, and the theoretical underpinnings tying membrane performance to membrane structure across multiple length scales is provided. The interplay of pore architecture and chemistry for a given set of analytes emerges as a critical design consideration dictating mass transport outcomes. Also discussed are opportunities and outstanding challenges in the field, including high-flux 2D molecular-sieving membranes, phase-change adsorbents as performance-enhancing components in composite membranes, and the need for quantitative metrologies for understanding mass transport in heterophasic materials and in micropores with unusual chemical interactions with analytes of interest.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Applications of CALPHAD modeling and databases in advanced lightweight metallic materials

Here this paper presents an overview on the application of CALPHAD (CALculation of Phase Diagrams) methodology in the design and development of advanced lightweight metallic materials including magnesium, aluminum, titanium, aluminum-based metal matrix composites, and high entropy alloys. In this work, CALPHAD methodology has been established and summarized from the construction of databases describing thermodynamics, atomic mobility, kinetics, thermo-physical properties (such as viscosity) to the application of computational design of lightweight materials. The examples in this paper have demonstrated the effectiveness and capability of CALPHAD methodology in accelerating the design of advanced lightweight materials by optimizing the compositions and various heat-treatment conditions, modifying the evolution of microstructures during processing, and finally predicting the mechanical properties (e.g., yield strength and hardness) of the lightweight components. Although the examples are given in lightweight alloys for structural applications, the fundamental methodology and modeling principles are applicable to all materials and engineering applications. Thus, the future of the advanced material design will be strongly based on development of CALPHAD methodology such as the construction of reliable databases coupled with CALPHAD-based models for various applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Conductive overbraid of continuous fiber thermoplastic composite tows

Here, to meet the increasing demand for lightweight materials with multifunctional capabilities, a new high-rate manufacturing method and material system, referred to as M-TOW ® (multifunctional-tow) is introduced. Overbraiding is used to incorporate highly conductive wire onto the continuous fiber reinforced tow (M-TOW ® ), offering a solution for integrating thermal and electrical conductivity into hybrid-molded composite structures. The conductivity performance of different wire configurations are compared before and after forming the M TOW ® , measuring electrical conductivities up to 5.5 x 10 5 S / cm and thermal conductivities up to 21 W / mK. Results conclude that the integration of conductive wires into thermoplastic preforms is a viable means of expanding the functionality of lightweight, high strength composite structures.

3-dimensional reinforcement↗
DOE OSTI2018

Deformation Mechanisms of Vertically Stacked WS 2 /MoS 2 Heterostructures: The Role of Interfaces

Here, the mechanical and optical properties generated due to the stacking of different atomically thin materials have made it possible to tune and engineer these materials for next-generation electronics. The understanding of the interlayer interactions in such stacked structures is of fundamental interest for structure and property correlation. Here, a combined approach of in situ Raman spectroscopy and mechanical straining along with molecular dynamics (MD) simulations has been used to probe one such interface, namely, the WS 2 /MoS 2 heterostructure. Vertical heterostructures on poly(methyl methacrylate), when flexed, showed signs of decoupling at 1.2% strain. Theoretical calculations showed strain-induced stacking changes at 1.75% strain. The sliding characteristics of layers were also investigated using scanning probe microscopy based nanoscratch testing, and the results are further supported by MD simulations. The present study could be used to design future optoelectronic devices based on WS 2 /MoS 2 heterostructures.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Phase engineering of layered anode materials during ion-intercalation in Van der Waal heterostructures

Transition metal dichalcogenides (TMDs) are a class of 2D materials demonstrating promising properties, such as high capacities and cycling stabilities, making them strong candidates to replace graphitic anodes in lithium-ion batteries. However, certain TMDs, for instance, MoS 2 , undergo a phase transformation from 2H to 1T during intercalation that can affect the mobility of the intercalating ions, the anode voltage, and the reversible capacity. In contrast, select TMDs, for instance, NbS 2 and VS 2 , resist this type of phase transformation during Li-ion intercalation. This manuscript uses density functional theory simulations to investigate the phase transformation of TMD heterostructures during Li-, Na-, and K-ion intercalation. The simulations suggest that while stacking MoS 2 layers with NbS 2 layers is unable to limit this 2H → 1T transformation in MoS 2 during Li-ion intercalation, the interfaces effectively stabilize the 2H phase of MoS 2 during Na- and K-ion intercalation. However, stacking MoS 2 layers with VS 2 is able to suppress the 2H → 1T transformation of MoS 2 during the intercalation of Li, Na, and K-ions. The creation of TMD heterostructures by stacking MoS 2 with layers of non-transforming TMDs also renders theoretical capacities and electrical conductivities that are higher than that of bulk MoS 2 .

25 ENERGY STORAGE↗
DOE OSTI2018

Floquet Engineering of Gapped 2D Materials

It is demonstrated theoretically that the interaction of gapped 2D materials (gapped graphene and transition metal dichalchogenide monolayers) with a strong high-frequency electromagnetic field (dressing field) crucially changes the band structure of the materials. As a consequence, the renormalized band structure of the materials drastically depends on the field polarization. Particularly, a linearly polarized dressing field always decreases band gaps, whereas a circularly polarized field breaks the equivalence of band valleys in different points of the Brillouin zone and can both increase and decrease corresponding band gaps. It is shown also that a dressing field can turn both the band gaps and the spin splitting of the bands into zero. As a result, the dressing field can serve as an effective tool to control spin and valley properties of the materials in various optoelectronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Campaign 76 - Production of 252 CF and the Recovery of Curium Feed Material at the Radiochemical Engineering Development Center

Californium-252 is a strong neutron emitter with several specialized uses. It is produced in the High Flux Isotope Reactor (HFIR) by irradiating curium targets followed by several steps, collectively called a processing campaign. These steps involve chemical processing at the Radiochemical Engineering Development Center (REDC) to recover and purify Cf and Cm, and to fabricate new targets using recovered Cm. The ultimate goal of a campaign is to replenish the Cf stock for the Californium Production Program. This report describes the processing and results of Campaign 76.

07 ISOTOPE AND RADIATION SOURCES↗