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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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Process for manufacturing SiC composite ceramics

A method is described for manufacturing a ceramic composite structure. The method includes wrapping ceramic fibers (22), such as SiC fibers, about the external surface of at least one form. The method further includes heating the wrapped fibers (22) to a temperature no greater than a first temperature, infiltrating voids (24) in the wrapped fibers (22) with the ceramic composite in a first vessel (12) at the first temperature, transferring the infiltrated wrapped fibers (22) from the first vessel (12) to a second vessel (14), distinct from the first vessel (12), and coating the infiltrated wrapped fibers (22) with the ceramic composite in the second vessel (14) at a second temperature, higher than the first temperature.

Lahoda, Edward J.↗
DOE OSTI2021

Optical sensor employing a refractive index engineered metal oxide material

An optical sensor device includes an optical waveguide portion having a core, the core having a first refractive index, and a functional material layer coupled to the optical fiber portion, the functional material layer being made of a metal oxide material, the functional material layer being structured to have a second refractive index, the second refractive index being less than the first refractive index. The functional material layer may be a nanostructure material comprising the metal oxide material with a plurality of holes or voids formed therein such that the functional material layer is caused to have the second refractive index.

Chen, Peng↗
DOE OSTI2021

Yolk-shell nanoparticle, method and applications

A nanoparticle and a method for fabricating the nanoparticle utilize a decomposable material yoke located within permeable organic polymer material shell and separated from the permeable organic polymer material shell by a void space. When the decomposable material yoke comprises a sulfur material and the permeable organic polymer material shell comprises a material permeable to both a sulfur material vapor and a lithium ion within a battery electrolyte the nanoparticle may be used within an electrode for a Li/S battery absent the negative effects of battery electrode materials expansion.

Yu, Yu↗
DOE OSTI2021

Resin transfer molding systems and control logic for manufacturing fiber-reinforced composite parts

Presented are manufacturing control systems for fabricating composite-material structures, methods for making/operating such systems, and resin transfer molding techniques for ameliorating race-tracking effects in fiber-reinforced polymer panels. A method for forming a composite-material construction includes confirming, via a system electronic control unit (ECU), that a fiber-based preform is placed in a mold cavity and that opposing mold segments of the molding apparatus are sealed together. A filler, such as a compressible bladder, a cluster of spring-biased pins, or a spray-chopped fiber bed, is introduced into a void between the fiber-based preform and a tool face of one mold segment to thereby eliminate an unwanted resin race track. The system ECU commands a resin pump to inject resin through a primary gate of the molding apparatus and into the mold cavity to thereby impregnate the fiber-based preform with the resin. One or more vents operate to evacuate air from the mold.

Rodgers, William R.↗
DOE OSTI2022

Scintillation Hydro-Gel for Isotopic Neutron (SHINE): Eco-Friendly Quantum Dot Neutron Detectors

The development of new neutron detectors to replace helium-3 (3He) detectors is imperative due to a worldwide shortage of 3He following the draw down in nuclear weapons production since the end of the Cold War. The United States Department of Homeland Security would like to deploy monitors for the detection of neutron emissions from shipping containers housing illicit nuclear material; however, this effort has been put on hold until new replacements for 3He detectors can be developed. Scintillation Hydro-Gel for isotopic Neutron Emitters (SHINE) is a unique, first of its kind, 6Li-loaded quantum dot gel scintillator developed at INL. By incorporating 6Li with quantum dots in a gel matrix, SHINE displays the best properties of liquid and solid scintillators without their disadvantages such as continuous filtering to keep liquids free of contaminates, slow throughput of containers, higher base component costs, ‘dead’ voids in solid scintillators, and a high loading of 6Li without compromising on light transparency. Additionally, SHINE is completely eco-friendly, a breakthrough in high-efficiency detection systems. SHINE is a unique combination of 6LiCl, a highly water-soluble compound, and InP/ZnS core/shell quantum dots, which are poured into a gel-form using cross-linking polymers. In this presentation, SHINE has been successfully tested for neutron detection and shows promise as both a replacement for current 3He neutron detectors as well as potential use in handheld, compact neutron detection units and antineutrino detection.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Dynamic properties of FeCrMnNi, a High Entropy Alloy

The goal of this paper was to assess the dynamic properties of a new class of materials, High entropy alloys (HEAs). Specifically, gas gun experiments coupled with recovery were performed on a specific HEA, FeCrMnNi, to measure its equation of state (EOS) and its spall strength, which is a measure of the stress required to nucleate voids under shock loading conditions. While there has been a plethora of work performed to assess the mechanical properties of these HEAs under uniaxial stress conditions as a function of strain rate, investigation of its properties in dynamic extremes remains rare. The current work fills this gap in knowledge for this novel class of materials. Our results show that the measured EOS for this material at one velocity was in reasonable agreement with an estimated Hugoniot. Furthermore, while the spall strength for this material was found to be ~1.9 GPa, with some variation based on sample location, the main failure mode wasbrittle. This brittle failure leading to formation of cracks in the material is different than the ductile failure observed in pure iron and its alloys. DOE/NV/03624--1298

36 MATERIALS SCIENCE↗
DOE OSTI2021

High Entropy Alloys: Irradiation

High entropy alloys (HEAs) have been considered as structural materials for nuclear applications due to their promising mechanical properties and radiation resistance. For this purpose, irradiation-induced defect evolution and microstructure change have been characterized to evaluate the irradiation performance of different HEAs. This article reviews recent advances in understanding the irradiation response of HEAs, including the effect of disordered states on the defect energy landscape and defect evolution, irradiation-induced microstructure changes, void swelling, phase stability, mechanical properties under irradiation, as well as the He irradiation effects.

Zhao, Shijun↗
DOE OSTI2021

Carbon dioxide capture system and method with mass transfer contactor

A carbon dioxide capture system, fluid contactor and method are disclosed. In embodiments, a gas-liquid contactor unit is disposed along a process fluid flow axis and includes a contactor network of flow diversion barriers with flow voids for movement of process fluids therebetween. A plurality of heat exchange channels are provided in the flow diversion barriers to transport a heat exchange fluid through the contactor network. A heat exchange feed channel is provided to deliver feed of the heat exchange fluid to the heat exchange channels at multiple feed locations spaced along the flow axis. At least one heat exchange bypass channel may extend beyond the multiple feed locations to deliver a portion of the feed of the heat exchange fluid to additional heat exchange channels located downstream from the multiple feed locations for the heat exchange channels.

Panaccione, Charles↗
DOE OSTI2021

Methods of forming fuel rods comprising porous fuel materials

A method of forming a fuel rod for a nuclear reactor comprises disposing a powder comprising particles of a fuel material on a substrate, exposing the powder to energy from an energy source to form a first layer of a nuclear fuel, the first layer comprising inter-granular bonds between the particles of the fuel material, disposing additional powder comprising particles of the fuel material over the first layer of the nuclear fuel, and exposing the additional powder to energy from the energy source to form a second layer of the nuclear fuel and to form the nuclear fuel to have a void fraction greater than about 0.20, the second layer comprising inter-granular bonds between the additional powder and the first layer of the nuclear fuel. Related nuclear fuels comprising a porous structure, fuel rods, nuclear reactors, and methods are disclosed.

O'Brien, Robert C.↗
DOE OSTI2021

Encapsulated sulfur cathodes for rechargeable lithium batteries

A method of forming a sulfur-based cathode material includes: 1) providing a sulfur-based nanostructure; 2) coating the nanostructure with an encapsulating material to form a shell surrounding the nanostructure; and 3) removing a portion of the nanostructure through the shell to form a void within the shell, with a remaining portion of the nanostructure disposed within the shell.

Li, Weiyang↗
DOE OSTI2022

Sealability Qualification of Material Extruded Zytel Gaskets at Extreme Temperatures

In this work, an in-depth qualification of additively manufactured Zytel for gasketing proton exchange membrane fuel cells (PEMFC’s) subject to extreme temperature conditions. The temperature cycling of the PEMFC from 55°C to 100°C accelerates the deterioration of these gaskets compared to that of conventional operation. The additive manufacturing process employed to print these gaskets is material extrusion using Zytel filament. In order to see the effects of the temperature of interest on the printed specimen, each specimen was thermally soaked and then charactered and tested according to ASTM standard F37B. ASTM F37B tests a materials ability to seal and maintain it while bearing both a compressive load and internal pressure load to simulate being in static operation. This process of thermally soaking and sealability testing is shown to show the validity of both this material and additive manufactured components for other applications as well. It is observed that soaking the gaskets at 100°C corrects some of the defects that are present after printing such as missing layers and small voids on the surface of the samples. This allowed for the hot soaked materials to perform better than the samples at room temperature and cold soaked.

Sealability↗
DOE OSTI2022

Characterization of anisotropic mechanical properties of polymer composites from a hybrid additive manufacturing-compression molding process using x-ray computer tomography

In this study, anisotropic stiffness tensors were reconstructed based on fiber orientation distributions obtained from X-ray computer tomography (xCT). A preform was manufactured via a big area additive manufacturing (BAAM) system with carbon fiber (CF) filled acrylonitrile butadiene styrene (ABS). The tailored preform from additive manufacturing (AM) was used in the compression molding (CM) process to produce a low-void high-performance thermoplastic composite panel. An xCT technique was employed to detect the fiber orientations in CF/ABS composites manufactured via three different methods: AM from BAAM, extrusion compression molding (ECM), and AM-CM. The anisotropic stiffness tensor was obtained from the composite panel manufactured via the three manufacturing methods (AM, ECM, and AMCM). A micromechanics theory was used to obtain the orthotropic stiffness tensors of the composite panels and compared with the experimental values. The predicted stiffness tensors of AM and AM-CM composite panels were used to study the deformation characteristics of a steering wheel during airbag deployment by performing finite element analysis (FEA). The approach developed in this study can be utilized for evaluating high-performance composites.

Pokkalla, Deepak↗
DOE OSTI2022

MODELLING FIBER ORIENTATION DURING ADDITIVE MANUFACTURING COMPRESSION MOLDING PROCESSES

The production of high-performance thermoplastic composites reinforced with short carbon fibers can be achieved by a novel “additive manufacturing-compression molding” technique. An advantage of such combination is two-fold: controlled fiber orientation in additive manufacturing and less void content by compression molding. In this study, a computational fluid dynamics model has been developed to predict the behavior of printed layers during fiber-reinforced thermoplastic extrusion and subsequent compression molding. The fiber orientation was modelled with a simple quadratic closure model. The interaction between the fibers is included using a rotary diffusion coefficient which becomes significant in concentrated regimes. Finally, the second order orientation tensor is coupled with the momentum equation as an anisotropic part of the stress term. The effect of processing parameters on the behavior of printed layers was investigated to determine the favorable printing scenarios. The developed numerical model enables design of high-performance composites with tunable mechanical properties.

Seta, Berin↗
DOE OSTI2022

MODELLING OF ADDITIVE MANUFACTURING – COMPRESSION MOLDING PROCESS USING COMPUTATIONAL FLUID DYNAMICS

A computational fluid dynamics model has been developed to predict the behavior of a printed strands during a novel material extrusion additive manufacturing and compression molding process. While the traditional additive manufacturing process enables control over the fiber orientation within the part, it would also result in high void content. On the other hand, compression molding produces parts with low porosity levels at rapid processing cycle time but lacks control over the microstructure. The novel additive manufacturing – compression molding (AM-CM) integrating both these processes offers control over both the microstructure and porosity to manufacturing high performance composite parts. The numerical model developed here enables to analyze the effect of processing parameters on the behaviour of printed layer that is subsequently compressed and to determine the optimal printing parameters for high-performance composite part design.

Seta, Berin↗
DOE OSTI2022

Tunnel drift step recovery diode

Devices, methods and techniques are disclosed for providing a multi-layer diode without voids between layers. In one example aspect, a multi-stack diode includes at least two Drift Step Recovery Diodes (DSRDs). Each DSRD comprises a first layer having a first type of dopant, a second layer forming a region with at least ten times lower concentration of dopants compared to the adjacent layers, and a third layer having a second type of dopant that is opposite to the first type of dopant. The first layer of a second DSRD is positioned on top of the third layer of first DSRD. The first layer of the second DSRD and the third layer of the first DSRD are degenerate to form a tunneling diode at an interface of the first DSRD and second DSRD, the tunneling diode demonstrating a linear current-voltage characteristic.

Voss, Lars F.↗
DOE OSTI2022

High-voltage push to mate electrical interconnect

A high-voltage self-aligning push to mate electrical interconnect device is provided. The electrical interconnect device includes a housing with a mating end and a receiving end. The interconnect also includes an insulator bushing configured to be affixed to the receiving end of the housing. The interconnect also includes a center pin disposed within the housing. The center pin extends from the mating end of the housing to the receiving end of the housing. The interconnect also includes a connector socket disposed within the insulator bushing and which is in electrical communication with the center pin. The interconnect also includes an alignment sleeve including a chamfered mating funnel defining a void configured to accept and surround the housing and at least a portion of insulator bushing.

Martinez, David K.↗
DOE OSTI2022

High-Fidelity Measurements for Flattop-HEU Benchmark Reevaluation

Flattop was first built in the 1950’s at Los Alamos National Laboratory. Flattop-HEU is composed of a sphere of highly enriched uranium (HEU) surrounded by a thick spherical natural uranium (NU) reflector. The reflector is composed of three parts: a stationary hemisphere and two movable quarter spheres. For fine control of the reactivity of the system, there are three control rods of natural uranium located in voids in the stationary hemisphere. The final components that make Flattop a useful critical assembly are the glory hole and mass adjustment pieces. These pieces can be loaded in various configurations into the glory hole and the core pedestal to control the known worth of the system. The glory hole and mass adjustment pieces are mostly small pieces of HEU with some mass adjustment pieces fabricated from NU. This allows for the irradiation of samples to a specified level. To better document the system, Flattop was evaluated and included in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) handbook. The original benchmark evaluation of Flattop-HEU was written in 1999 based on an experiment completed in the 1960’s. This original evaluation was written to provide a single diameter that defined critical mass; however, as computational capabilities have increased, the focus for benchmark evaluations has shifted to include detailed modelswith all physical dimensions. Thus, as Flattop is a lynchpin in critical experiment work, the benchmark is being reevaluated at current standards. This summary discusses some of the largest known uncertainties from the evaluation and the high-fidelity measurements taken to reduce these uncertainties.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Ultrasonic Testing (UT) and Computed Tomography (CT) Comparative Scanning of Proposed Additive Manufacturing Reference Standard

This report presents qualitative results of ultrasonic full matrix capture/total focusing method (FMC/TFM) scanning of two series of blocks, additively manufactured by powder bed fusion, containing a variety of internal features and structures that would not be achievable by conventional manufacturing techniques. The purpose of the first series of additively manufactured (AM) blocks was to explore the possibility of building calibration blocks for FMC/TFM ultrasonic testing (UT). It was confirmed that AM is a suitable candidate for generation of unusual and novel reflector forms, such as rotating slots, purposely embedded voids, and tapering holes, and that FMC/TFM was very capable of characterizing them. The intended use of the second series of AM blocks was as UT reference blocks to characterize the AM process quality or the interrogating UT technique. The larger block in this series was scanned from multiple faces, using multiple UT methods (conventional UT and FMC/TFM) and X-ray computed tomography for comparative purposes. The performance of each method was quantified by a metric corresponding to the detection limit of each feature, and the quantitative results are discussed.

36 MATERIALS SCIENCE↗