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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 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Non-flammable electrolyte enables Li-metal batteries with aggressive cathode chemistries

Rechargeable Li-metal batteries using high-voltage cathodes can deliver the highest possible energy densities among all electrochemistries. However, the notorious reactivity of metallic lithium as well as the catalytic nature of high-voltage cathode materials largely prevents their practical application. Here, we report a non-flammable fluorinated electrolyte that supports the most aggressive and high-voltage cathodes in a Li-metal battery. Our battery shows high cycling stability, as evidenced by the efficiencies for Li-metal plating/stripping (99.2%) for a 5 V cathode LiCoPO 4 (-99.81%) and a Ni-rich LiNi 0.8 Mn 0.1 ,Co 0.3 ,O 2 cathode (-99.93%). At a loading of 2.0 mAh cm -2 , our full cells retain -93% of their original capacities after 1,000 cycles. Surface analyses and quantum chemistry calculations show that stabilization of these aggressive chemistries at extreme potentials is due to the formation of a several-nanometre-thick fluorinated interphase.

Fan, Xiulin↗
DOE OSTI2018

RHEGAL: Resistive heating gas enclosure loadframe for in situ neutron scattering

In situ neutron scattering is a powerful tool to reveal materials atomic structural response such as phase transformation, lattice straining, and texture under external stimuli. The advent of a high flux neutron source such as the Spallation Neutron Source (SNS) allows fast measurement in even non-equilibrium conditions, i.e., phase transformation in steels. However, the commercial fast heating apparatus such as commercial physical simulation equipment is not designed for in situ neutron scattering, which limits its application to in situ materials research by using neutrons. Here we present a resistive heating gas enclosure loadframe (RHEGAL) for non-equilibrium phase transformation studies by using in situ neutron scattering, which takes the advantage of high flux neutron sources like SNS. RHEGAL enables fast resistive heating of metal samples to 1200 °C at a rate up to 60 °C/s in an inert atmosphere. It provides both horizontal and vertical positions for scattering optimization. The mechanical loading capability also allows in situ high temperature tension above the oxidation temperature limit. The optimized translucent neutron scattering window by silicon allows both reflection and transmission measurements, making this equipment applicable for neutron diffraction, small angle scattering, and imaging. Furthermore, to demonstrate the fast heating capability, the phase transformations of an example of advanced high strength steel heated at 3 °C/s and 30 °C/s were measured with the VULCAN engineering diffractometer, and the different phase transformation kinetics by neutron diffraction were presented.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Isotopic targets with graphene backing

Many of the isotopes cannot be made as free-standing targets and require thin film backing. Low-Z backing materials, such as amorphous carbon and thin polymer films are materials of choice for some experiments. However, the limitations of these backing materials are poor thermal and mechanical stability. All-carbon graphene films would be an excellent choice as a backing material due to their high thermal conductivity, high temperature tolerance (3550ºC melting point), low outgassing, mechanical integrity, and ease of handling. We fabricated a variety of targets using graphene material as a backing or a host matrix. Using PVD sputtering deposition of boron-11 carbide, we fabricated 11 B target with a 0.5 mg/cm 2 on graphene film. The 11 B isotope is of interest due to aneutronic proton–boron fusion reaction 1 p + 11 B → 3 4 He + 8.7 MeV suitable for clean energy production1. We also prepared a neutron rich natCr target on graphene backing by electroplating Cr in an aqueous chromium (III) oxide bath. The chromium target can be used for production of positron emitting Mn radioisotope2 in the reaction 52 Cr (p,n) 52 Mn. One of the unique advantages of the graphene film fabrication process is the capability to embed target materials, including refractory metals, in the nanoparticle form into a host graphene matrix during target preparation. Finally, we fabricated nat Ir, nat Re, nat WO3, and nat HfO 2 nanoparticle-loaded graphene targets that can be used in nuclear physics research.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Innovations in the vapor deposition of metal coatings for target payloads in laser-based physics experiments under extreme conditions

The synthesis of metal foils with unique surface features such as waves and steps is of interest for use as payloads in targets for laser-driven physics experiments under dynamic loading conditions. Changes to the surface features are used to quantify the effects of the material strength during the deformation at high-strain rate high pressure. Additionally, a traditional path to produce these target features is by precision machining processes using diamond tools. Limitations are encountered since many of the materials of interest and the size of the surface features are not often compatible with conventional machining-process methods. An alternative method to produce targets with unique surface features is through vapor synthesis. Two general approaches are taken—one is by replicating the features from the surface of a substrate mandrel, whereas the second is by using hard masks with timed exposure to the deposition vapor. In these approaches, postdeposition removal of a release layer yields a free-standing target with the desired surface features. Here, specific cases are presented for the physical vapor deposition of copper, aluminum, iron, vanadium, and tantalum to form targets with multiple layers, steps, and sinusoidal surface waves.

36 MATERIALS SCIENCE↗
DOE OSTI2019

DE-SC0004913: The role of microstructural neighborhoods in forming and evolving slip localization in polycrystalline metals during cyclic plasticity (Final Report)

During this grant we processed and analyzed data from High Energy X-ray Diffraction (HEXD). We conducted a study of the evolution of an aggregate of commercially pure copper crystals subjected to cyclic loading conditions consistent with low cycle fatigue (LCF); each fatigue cycle contains macroscopically elastic-plastic deformation. The uniaxial test specimen initially loads elastically and yields in tension, then unloads elastically and re– yields in compression. The macroscopic cyclic stress-strain curve forms characteristic hysteresis loops that change in size (typically increase) with each cycle reflecting the plasticity-induced material evolution that is taking place within each crystal. It has been hypothesized that at some point, the to-and-fro plastic slip within one crystal or a group of crystals initiates a fatigue crack. Using HE x-ray diffraction we studied the cyclic plasticity within every deforming crystal by measuring how the lattice misorientation changes as the sample is loaded around the hysteresis loop.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Evaluation of boron-epoxy-reinforced titanium tubular truss for application to a space shuttle booster thrust structure

Results of a study to demonstrate the applicability of boron-epoxy-composite-reinforced titanium tubular members to a space shuttle booster thrust structure are presented and discussed. The experimental results include local buckling of all-composite and composite-reinforced-metal cylinders with low values of diameter-thickness ratio, static tests on composite-to-metal bonded step joints, and a test to failure of a boron-epoxy-reinforced titanium demonstration truss. The demonstration truss failed at 118 percent of design ultimate load. Test results and analysis for all specimens and the truss are compared. Comparing an all-titanium design and a boron-epoxy-reinforced-titanium (75 percent B-E and 25 percent Ti) design for application to the space shuttle booster thrust structure indicates that the latter would weigh approximately 24 percent less. Experimental data on the local buckling strength of cylinders with a diameter-thickness ratio of approximately 50 are needed to insure that undue conservatism is not used in future designs.

Corvelli, N.↗
NASA NTRS1979

Study of polyphenyl ether fluid /5P4E/ in operating elastohydrodynamic contacts by infrared emission spectroscopy

Infrared emission spectra of 5P4E polyphenyl ether were obtained from an operating elastohydrodynamic sliding contact at different speeds and loads by Fourier emission microspectrophotometry. The spectra were found to be polarized with respect to the direction of the conjunction line, especially at high shear rates. Film and metal surface temperatures were calculated from the spectra, and film thicknesses were determined under various operating conditions. Changes of polarized band structure above a critical shear rate, at which the slope of the film temperature versus shear curve changes abruptly and at which the film thickness assumes a minimum value, are consistent with a transition of the lubricant from a viscous liquid to a viscoelastic liquid or to an elastic solid.

Lauer, J. L.↗
NASA NTRS1988

Thermoviscoplastic nonlinear constitutive relationships for structural analysis of high-temperature metal matrix composites

A set of thermoviscoplastic nonlinear constitutive relationships (TVP-NCR) developed for application to high-temperature metal matrix composites (HT-MMC) is described. The structural response of a turbine blade, made from fiber-reinforced superalloy HT-MMC and subject to representative loading conditions, is evaluated. Results indicate that this set of TVP-NCR is computationally effective.

Chamis, Christos C.↗
NASA NTRS1990

Thermoviscoplastic behavior of SCS6/Ti metal matrix composites

Experimental measurements are described which can be applied to the development and evaluation of four thermoviscoplastic models of multiangle metal matrix composites. The measurements are employed to develop a data base of stress-strain-time response of SCS6/Ti-15-3 specimens that involves three high temperatures and three loading scenarios. Results of the testing and general data are given for the titanium specimens and are of interest to the development of a method for the measurement and prediction of thermoviscoplastic behavior.

Rogacki, J.↗
NASA NTRS1993

Energy dissipator

An all metal energy dissipator construction is disclosed for dissipating kinetic energy force (F) by rolling balls which are forced by a tapered surface on an expandable sleeve to frictionally load a force rod. The balls are maintained in an initial position by a plate member which is biased by a spring member. A spring member returns the force rod to its initial position after a loading force is removed.

Delafuente, Horacio M.↗
NASA NTRS1998

Method for Surface Texturing Titanium Products

The present invention teaches a method of producing a textured surface upon an arbitrarily configured titanium or titanium alloy object for the purpose of improving bonding between the object and other materials such as polymer matrix composites and/or human bone for the direct in-growth of orthopaedic implants. The titanium or titanium alloy object is placed in an electrolytic cell having an ultrasonically agitated solution of sodium chloride therein whereby a pattern of uniform "pock mark" like pores or cavities are produced upon the object's surface. The process is very cost effective compared to other methods of producing rough surfaces on titanium and titanium alloy components. The surface textures produced by the present invention are etched directly into the parent metal at discrete sites separated by areas unaffected by the etching process. Bonding materials to such surface textures on titanium or titanium alloy can thus support a shear load even if adhesion of the bonding material is poor.

Banks, Bruce A.↗
NASA NTRS2000

Advances in Fatigue and Fracture Mechanics Analyses for Metallic Aircraft Structures

This paper reviews some of the advances that have been made in stress analyses of cracked aircraft components, in the understanding of the fatigue and fatigue-crack growth process, and in the prediction of residual strength of complex aircraft structures with widespread fatigue damage. Finite-element analyses of cracked metallic structures are now used to determine accurate stress-intensity factors for cracks at structural details. Observations of small-crack behavior at open and rivet-loaded holes and the development of small-crack theory has lead to the prediction of stress-life behavior for components with stress concentrations under aircraft spectrum loading. Fatigue-crack growth under simulated aircraft spectra can now be predicted with the crack-closure concept. Residual strength of cracked panels with severe out-of-plane deformations (buckling) in the presence of stiffeners and multiple-site damage can be predicted with advanced elastic-plastic finite-element analyses and the critical crack-tip-opening angle (CTOA) fracture criterion. These advances are helping to assure continued safety of aircraft structures.

Newman, J. C., Jr.↗
NASA NTRS2002

Characterization of Ceramic Matrix Composite Fasteners Exposed in a Combustion Liner Rig Test

Combustion tests on SiC/SiC CMC (Ceramic Matrix Composite) components were performed in an aircraft combustion environment using the Rich-burn, Quick-quench, Lean-burn (RQL) sector rig. SiC/SiC fasteners were used to attach several of these components to the metallic rig structure. The effect of combustion exposure on the fastener material was characterized via microstructural examination. Fasteners were also destructively tested, after combustion exposure, and the failure loads of fasteners exposed in the sector rig were compared to those of as-manufactured fasteners. Combustion exposure reduced the fastener failure load by 50% relative to the as-manufactured fasteners for exposure times ranging from 50 to 260 hours. The fasteners exposed in the combustion environment demonstrated failure loads that varied with failure mode. Fasteners that had the highest average failure load, failed in the same manner as the unexposed fasteners.

Verrilli, Michael J.↗
NASA NTRS2010

Design of Refractory Metal Life Test Heat Pipe and Calorimeter

Heat pipe life tests have seldom been conducted on a systematic basis. Typically, one or more heat pipes are built and tested for an extended period at a single temperature with simple condenser loading. Results are often reported describing the wall material, working fluid, test temperature, test duration, and occasionally the nature of any failure. Important information such as design details, processing procedures, material assay, power throughput, and radial power density are usually not mentioned. We propose to develop methods to generate carefully controlled data that conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. The test approach detailed in this Technical Publication will use 16 Mo-44.5%Re alloy/sodium heat pipe units that have an approximate12-in length and 5/8-in diameter. Two specific test series have been identified: (1) Long-term corrosion rates based on ASTM-G-68-80 (G-series) and (2) corrosion trends in a cross-correlation sequence at various temperatures and mass fluences based on a Fisher multifactor design (F-series). Evaluation of the heat pipe hardware will be performed in test chambers purged with an inert purified gas (helium or helium/argon mixture) at low pressure (10-100 torr) to provide thermal coupling between the heat pipe condenser and calorimeter. The final pressure will be selected to minimize the potential for voltage breakdown between the heat pipe and radio frequency (RF) induction coil (RF heating is currently the planned method of powering the heat pipes). The proposed calorimeter is constructed from a copper alloy and relies on a laminar flow water-coolant channel design to absorb and transport energy

Martin, J. J.↗
DOE OSTI2022

A Machine Learning-Assisted Framework to Control Thermally Anisotropic Building Envelopes in Residential Buildings

To curb the energy consumption of buildings and their related CO2 emissions, Oak Ridge National Laboratory (ORNL) has developed the thermally anisotropic building envelope (TABE) —a multi-layer design comprising insulation materials and metal foils connected to thermal loops. In this study, a machine learning-assisted framework was developed to control the TABE in residential buildings to reduce the computation load for future optimal rule-based control and application. First, a 2D finite element model was established in COMSOL to calculate the hourly heat flux through exterior walls installed with the TABE. Then, TABE wall heat fluxes were simulated for various given indoor and outdoor boundary conditions, as well as thermal loops fluid temperatures and flow rates. Since the finite element simulations are computationally expensive, an artificial neural network (ANN) was then trained to use as a proxy of the finite element (COMSOL) modeling. Finally, the trained ANN model was coupled with the EnergyPlus model to predict the energy consumption of a US Department of Energy prototype single-family house installed with the TABE. An optimal simple rule-based control was determined from predefined rules for a case study. The results demonstrate that the developed machine learning–assisted framework can reduce 99.9% of the computation time while efficiently managing residential building energy for installed TABE walls.

Shen, Zhenglai↗
DOE OSTI2017

Sliding of coherent twin boundaries

Coherent twin boundaries (CTBs) are internal interfaces that can play a key role in markedly enhancing the strength of metallic materials while preserving their ductility. They are known to accommodate plastic deformation primarily through their migration, while experimental evidence documenting large-scale sliding of CTBs to facilitate deformation has thus far not been reported. We show here that CTB sliding is possible whenever the loading orientation enables the Schmid factors of leading and trailing partial dislocations to be comparable to each other. This theoretical prediction is confirmed by real-time transmission electron microscope experimental observations during uniaxial deformation of copper pillars with different orientations and is further validated at the atomic scale by recourse to molecular dynamics simulations. Our findings provide mechanistic insights into the evolution of plasticity in heavily twinned face-centered cubic metals, with the potential for optimizing mechanical properties with nanoscale CTBs in material design.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Loading Capabilities of Irradiated 3-D Printed Polymers

Gamma radiation is the emission of a high-energy photon from a radioactive source. The photon then interacts with an atom potentially damaging it. While time has shown that gamma radiation has a little effect on metals, the same cannot be said about plastic. The use of these types of materials in radioactive areas has increased for many reasons ranging from the weight difference between plastics and metals to the costs associated with doing so. For example, a potential use for radiation resistant plastics could be longer lasting, cost effective, and light weight radiation detection devices sent to probe an area that may present unsafe conditions for humans to survey. For these reasons and more, finding a plastic polymer that can withstand radiation for an extended period of time would make a great impact on the nuclear industry. In this experiment, two different polymers will undergo a series of strength tests before and after being exposed to radiation after different amounts of time up to two weeks. There are two sets of plastic polymers that will be used. Each set will consist of an nonirradiated, control subset, and subsets subject to radiation for one day, one week, and two weeks. The radiation source is 1100 Ci cobalt- 60. The specimens are placed on a foam platform such that they will be exposed as evenly as possible. They are then lowered into the radiation chamber where they are surround by cobalt-60 sources and irradiated for the given amount of time. The specimens will be tested for tensile strength and flexural strength according to ASTM standards. For tensile testing, the specimen has a 'dog bone' shape. The specimen is gripped at the wide ends, and pulled away from the center at a constant rate until failure. To test flexural strength, the specimens will be subject to a 3-point bend test. The specimen is held in place by three points, center top side and both ends bottom side. Load is applied at a constant rate on the center of the specimen until failure. The calculations to be considered for comparison after performing these tests include the tensile strength and stress, elongation, flexural stress and strain, and elasticity. Once these tests are completed, testing specimens that have been 3D printed with different print orientations will be considered and tested. The results from both experiments will help create strong, radiation resistant products in a expeditious manner that could really push the current limitations and expand the use of radiation resistant material.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Management of Alkali and Alkaline Earth Fission Products in Used Pyroprocessing Salt

Pyroprocessing of spent nuclear fuel (SNF) involves dissolving metallic fuel into a molten salt electrolyte (typically eutectic LiCl-KCl) and then preferentially depositing actinides onto inert cathodes. Subsequent operations include drawdown of residual actinides and lanthanides from the electrolyte prior to re-using the salt. The recovered actinides are recycled and the recovered lanthanides are disposed as waste. Alkali and alkaline earth metal fission products in the fuel, such as Cs, Sr and Ba, dissolve into the salt during electrorefining. The concentrations of these elements buildup over time in the molten salt electrolyte, which may change the freezing point. The radioactive decay of 137 Cs and 90 Sr (half life 30 and 29 years) generates significant heat and produces strong ionizing radiation fields (β and γ). The increasing heat load and radioactivity as these elements build up in the molten salt requires frequent replacement and disposal of the electrolyte salt. Alternatively, the salt can be treated to remove these and other elements and then recycled to the electrorefiner. An effective strategy to manage these alkali and alkaline earth metal fission products in the molten salt electrolyte would increase the efficiency of pyroprocessing and decrease the volume of salt waste requiring disposal. Alkali and alkaline earth metal fission products are extremely stable in molten salt as chlorides--even more stable than the LiCl-KCl eutectic base salt--making them challenging to remove. They are not removed during drawdown operations to recover residual actinides and lanthanides and a separate operation is required to sufficiently purify the salt for reuse. This work is focused on selecting a method for separating Cs, Sr and Ba from the salt recovered from the lanthanide drawdown operation prior to recycling the cleaned salt back to the electrorefiner. Not addressed in this work is the management of the waste stream produced by the separation. This report summarizes the issues to be addressed when developing removal strategies for cesium, strontium, and barium and reviews existing methods to identify suitable methods and any technological gaps in their application.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗