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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Purification of Gas and Liquid Streams Using Composite Sorbents Embedded in a Polyacrylonitrile Matrix

As new sorbents are developed for purifying gases or liquids via physisorption and/or chemisorption processes, the objective is typically to increase the specific surface area (SSA) to maximize the available binding sites for capturing various species of interest. One downfall to making a sorbent more porous is that it often leads to a product that is fragile or friable and can be damaged (resulting in unwanted powders), thus imposing process limitations. Techniques can be used to enhance the mechanical integrity of a sorbent, including heat treatments or pelletization with extrusion or granulation processes, but these can result in collapsed, unavailable pore structures within the sorbent, which decreases the diffusivity and eventually reduces the capacities of target species. An alternative approach for improving the mechanical integrity of the sorbent is to bind it (or encapsulate it) within a porous matrix that passively holds the sorbent in place. Typically, this approach leads to a decrease in sorption efficiency on the basis of starting sorbent mass, because the active sorbent is diluted by the binding matrix material and the active surfaces of the sorbent are somewhat obscured by the binding matrix; however, it comes with the advantage that the active sorbent is held in place and better protected from disintegrating during operation. One approach to securing the active sorbent is to embed it in a macroporous, passive polyacrylonitrile (PAN) matrix to create a composite sorbent. When optimized, the PAN matrix is highly porous and allows for gaseous or aqueous media transport through the product, providing adequate binding site access between the active sorbent and the species of interest. Including a polymer in the composite sorbent limits the maximum operating temperature, above which the composite sorbent incurs loss of structural integrity (e.g., decomposes) and/or reduction in SSA. Composite sorbents have been demonstrated with sulfide aerogels (SnS-PAN) for capturing I2(g), hydrogen mordenite (HZ-PAN) and silver-exchanged mordenite (AgZ-PAN) for capturing Kr and Xe, nanoparticle metal oxides (Nano-Composite Arsenic Sorbent, or N-CAS) for removing arsenic from water, ammonium molybdophosphate (AMP-PAN) for removing cesium-137 (137Cs) from aqueous nuclear waste streams, and The Phosphate Sponge (TPS) composite, which is being used to remove inorganic/ortho-phosphates in water treatment processes to mitigate introduction to the environment, which impedes toxic algae bloom formations. This chapter provides details on production of these materials along with options to optimize the synthesis process. It also includes experimental techniques to characterize products and assess their performance.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Purification of Gas and Liquid Streams Using Composite Sorbents Embedded in a Polyacrylonitrile Matrix

As new sorbents are developed for purifying gases or fluids via physisorption and/or chemisorption processes, the push is typically to increase the available specific surface area (SSA) to maximize the available binding sites for capturing various species of interest. One downfall to making a sorbent more porous is that it often leads to a product that is fragile or friable and can be damaged (resulting in unwanted powders), thus imposing process limitations. Techniques can be used to enhance the mechanical integrity of a sorbent including heat treatments or pelletization with extrusion or granulation processes but these can result in collapsed, unavailable pore structures within the sorbent, which leads to decreased diffusivity and eventual reduction of desired capacities of target species. An alternative approach for improving the mechanical integrity of the sorbent is to bind it (or encapsulate it) within a porous matrix that passively holds the sorbent in place. Typically, this approach leads to a decrease in sorption efficiency on the basis of starting sorbent mass, because the active sorbent is diluted by the binding matrix material and the active surfaces of the sorbent are somewhat obscured by the binding matrix, but it comes with the advantage that the active sorbent is held in place and better protected from powderization during operation. One approach to accomplish this is to embed the active sorbent in a macroporous passive polyacrylonitrile (PAN) matrix to create a composite sorbent. When optimized, the PAN matrix is highly porous and allows for gaseous or aqueous media transport through the product providing adequate binding site access between the active sorbent and the species of interest. Including a polymer in the composite sorbent limits the maximum operating temperature above which the composite sorbent incurs loss of structural integrity (e.g., decomposes) and/or reduction in SSA. Composite sorbents have been demonstrated with sulfide aerogels (SnS-PAN) for capturing I2(g), hydrogen mordenite (HZ-PAN) and silver-exchanged mordenite (AgZ-PAN) for capturing Kr and Xe, nano-particle metal oxides (N-CAS) for removing arsenic from water, ammonium molybdophosphate (AMP-PAN) for removing 137Cs from aqueous nuclear waste streams, and the phosphate sponge (TPS) composite, which is being used to remove inorganic and orthophosphates from water treatment processes to mitigate introduction to the environment impeding toxic algae bloom formations. This chapter provides details on production of these materials along with options to optimize of the synthesis process. It also includes experimental techniques to characterize products and assess their performances.

polyacrylonitrile, aerogel, gaseous capture, aqueo↗
DOE OSTI2019

Processing and Characterization of Pilgered 14YWT Tubing

The Nuclear Technology Research & Development program of the Office of Nuclear Energy has implemented a program to develop an advanced reactor cladding fabrication capability by using the extrusion and pilgering processes. Oxide-dispersion strengthened (ODS) steels are a promising class of advanced materials, but processes need to be developed to produce tubing for these advanced alloys. The Pacific Northwest National Laboratory (PNNL) has converted its rolling mill into a lab-scale pilger mill, which required designing pilger tooling and rolls that contained multiple pilgering grooves and designing a servo-driven feed mechanism. Upon assembling and checking out the system, pilgering runs on stainless steel, MA956, and 14YWT iron (Fe)-based alloys were completed. Once the feed rates and rotation rates were established, the reduction schedules were determined. This report will focus on the processing and characterization of pilgered 14YWT thin-wall tubing that was processed from an extruded thick-wall tube using the PNNL laboratory pilger rolling mill. Characterization included optical metallography of the pilgered tube and microhardness of the processed material. The 14YWT characterization is being done in cooperation with researchers at Los Alamos National Laboratory (LANL), with LANL performing mechanical property testing of pilgered 14YWT and 14YWT tubes produced by hydrostatic extrusion at Case Western Reserve University (CWRU).

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

The plastic flow machining: A new SPD process for producing metal sheets with gradient structures

Highlights: • A new process named Plastic Flow Machining is presented to produce thin sheets by an extrusion operation from bulk material. • The produced sheets present ultra-fine grain structures, good mechanical properties and high formability. • A deformation gradient was found across the thickness of the sheet regarding plastic strain, microstructure and texture. - Abstract: A new severe plastic deformation process is presented – the plastic flow machining – an extrusion process during which a sheet is formed through a lateral opening of the die in a single operation. The sheet is heavily deformed presenting an ultra-fine grain structure. Experimental results are presented for commercially pure aluminum concerning microstructures, textures and mechanical properties. A gradient structure was found across the thickness of the sheet concerning plastic strain, grain size and texture. Only simple shear textures were seen. The material strength increased by a factor of three with significant ductility and with relatively high Lankford parameter.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The influence of dynamic rheological properties on carbon fiber-reinforced polyetherimide for large-scale extrusion-based additive manufacturing

Printing high-performance thermoplastics on large scale extrusion-based additive manufacturing platforms requires stability over a range of processing conditions. Yet, research on the melt dynamics and processing conditions of these thermoplastics in big area additive manufacturing (BAAM) are limited. This report characterizes the dynamic rheological behavior of polyetherimide (PEI), a high-performance thermoplastic, as well as carbon fiber (CF)-reinforced PEI composites as a BAAM feedstock material. The viscoelastic properties, such as the storage and loss moduli and complex viscosity, are investigated in relation to the BAAM extrusion process. The results show that CF-PEI composites behave like a viscous liquid during BAAM extrusion. The addition of CF to PEI enhances the shear thinning effect and significantly increases the complex viscosity (2.5× increase for 20% CF, and 3× for 30% CF). The increased viscosity increases the torque on the extruder, which may be alleviated by increasing the material processing temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Microstructure and mechanical properties of 7075 aluminum alloy nanostructured composites processed by mechanical milling and indirect hot extrusion

Nanostructured composites of 7075 aluminum alloy and carbon coated silver nanoparticles were produced by mechanical milling and indirect hot extrusion. The milling products were obtained in a high energy SPEX ball mill, and then were compacted by uniaxial load and pressure-less sintered under argon atmosphere. Finally, the sintered product was hot extruded. Carbon coated silver nanoparticles were well distributed in the matrix of the extruded material. Tensile tests were carried out to corroborate the hypothesis that second phase particles, well dispersed in the matrix, improve the strength of the material. High resolution transmission electron microscopy was employed to locate and make sure that the silver nanoparticles were homogeneously and finely dispersed. Highlights: Black-Right-Pointing-Pointer 7075 Al nanostructured composites can be produced by mechanical milling. Black-Right-Pointing-Pointer Carbon coated silver nanoparticles are well dispersed into aluminum matrix. Black-Right-Pointing-Pointer Ductile Ag-C NP's improve the mechanical properties of the 7075 Al-alloy. Black-Right-Pointing-Pointer Ag-C NP's content has an important effect in the particle and crystallite size. Black-Right-Pointing-Pointer Ag-C NP's keep their morphology after milling and conformation processes.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Copper carbon composite wire with a uniform carbon dispersion made by friction extrusion

Copper-carbon composites are a group of materials with excellent mechanical, electrical, thermal, and tribological properties. However, bulk size copper-carbon composites made by the traditional manufacturing processes, like rolling or extrusion, fall short of reaching some of these properties predicted by theory or demonstrated only by samples at centimeter scale or smaller. The two main challenges to the successful scaling-up are: 1) to uniformly disperse carbon in the metal matrix; 2) to avoid degradation due to oxidation or reaction from overheating. In this work, we first demonstrate friction extrusion as a new method to make bulk-size void-free copper-carbon composite wires with homogenized carbon dispersion. Three different carbon varieties, graphite powder, graphene nanopowder, and carbon nanotubes, were added to the copper matrix with the concentration ranging from 0.5 wt% to 15 wt%. Special tooling, processing parameters, and procedures were developed, especially for high carbon content samples. Ten-fold reductions of both copper grain size and carbon particle size were achieved and attributed to the high shear deformation. Energy dispersive X-ray spectrometry indicates the carbon powder was refined to a sub-micron level and uniformly dispersed in the copper matrix. Compared with that of pure copper, the thermal capacity of the composite wire increases by 30 % while density reduces by 29 %.

Friction extrusion, Metal matrix composite, Graphe↗
NASA NTRS2019

Optimization of Aluminum-Tin Ink Composition and Sintering in Atmospheric Conditions

This study will focus on the basics of generating an aluminum-tin ink that can sinter in air and exhibits properties near that of a solid aluminum-tin alloy. Sintering temperatures will also be assessed in this study. Once the optimal aluminum ink composition is determined, the optimal ink thickness for homogeneous sintering must be determined by additional experimentation. Additive manufacturing is a rapidly developing and growing manufacturing process and has proven successful in many different ways. Processes, such as extrusion three-dimensional (3D) printing and selective laser melting (SLM), have proven to work but have limitations, such as material capabilities or density issues. SLM is a revolutionary process for additive manufacturing of metals but cannot be used in outer space due to the need for metallic powder which would diffuse into the atmosphere in a zero-gravity environment. For this reason, metallic ink additive manufacturing is a potential solution. Work is being done on metallic ink additive manufacturing in a vacuum for electrical applications. This project has focused on developing an aluminum-tin metallic ink that can sinter without the need of a vacuum or inert gas-purged atmosphere in order to prevent oxidation of the aluminum by adding flux. Once a potential ink composition has been determined through sintering of small disks and thin layers of ink, the ink may be studied with a multimaterial 3D printer at NASA Marshall Space Flight Center (MSFC) in future experiments. If successful, this aluminum-tin ink will be capable for use on the International Space Station to make replacement parts quickly. Along with its zero-gravity advantages, this ink may also have applications on Earth because it may be extruded on a substrate with precise ceramic tips in a 3D printing process. This would allow the fabrication of precise, complex shapes and may generate a much faster and more efficient printing process as compared with traditional powder bed additive manufacturing processes. The process would not be limited by a small building volume because the system would not require an enclosed chamber.

Courtright, Z. S.↗
DOE OSTI2022

Anisotropic thermal behavior of extrusion-based large scale additively manufactured carbon-fiber reinforced thermoplastic structures

Large format additive manufacturing (AM) enables rapid manufacturing of large parts and structures with minimum waste in material and energy. Extrusion-based AM deposition processes provide parts with highly anisotropic thermal properties, which are not typically reflected in textbook values for these materials. In order to develop accurate models that describe the directionally dependent thermal behavior of these materials in processing and service, accurate measurements of specific heat capacity and thermal conductivity are required. Here, this work characterizes, documents, and analyzes the effect of the anisotropic nature of the extrusion-based deposition process on the specific heat capacity and thermal conductivity of the resulting AM products. All measurements were made over a temperature range of 20–180°C using the transient plane source technique, also referred to as the hot disk technique. Three of the most commonly used large format AM feedstock materials that utilize carbon fiber reinforcement were examined in this work: acrylonitrile butadiene styrene, polyphenylene sulfide and polyphenylsulfone. Finally, these findings can serve as a thermal design/process guideline for future large format AM applications.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Imulation of polymer forming processes - addressing industrial needs

The objective of this paper is to present the development of simulation and design optimization capabilities, for polymer forming processes, in the context of addressing industrial needs. Accomplishments generated from close to twenty years of research in this field, at the National Research Council (NRC), are presented. Polymer forming processes such as extrusion blow moulding, stretch blow moulding and thermoforming have been the focus of the work, yet the research is extendable to similar polymer forming operations such as micro-blow moulding, sheet blow moulding and composites stamping. The research considers material models, process sequence integration and design optimization, derivative processes and 3D finite elements with multi-body contact.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Building a Simplistic Automatic Extruder: Instrument Development Opportunities for the Laboratory

This work presents an automatic extruder as a research experience for undergraduate students. The system offers a user-friendly approach to preparing vesicles, such as liposomes or polymersomes, with a defined size and polydispersity properties crucial for research in biology and macromolecules. It comprises two syringe pumps connected by a membrane filter. The setup is controlled by software. Compared to manual extrusion, this automated system provides advantages, such as precisely controlled variables. The project describes a tool to enhance undergraduate learning in science and engineering laboratories. Building an automatic extruder serves as a simplified model of a complex industrial process. It offers a clear advantage: automating a well-understood manual extrusion process. To make this project accessible, it is broken down into three manageable tasks: software development, hardware assembly, and testing procedures. This breakdown describes the software created, the hardware components used, and the testing procedures conducted for this project. All project data, including software code, testing data, and procedures, are freely available online. This allows undergraduate students to not only begin their own projects but also contribute to this educational instrument’s ongoing development.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Development and Advanced Process Simulation for Additive Manufacturing with Fiber-Reinforced Thermoplastics (Final Technical Report)

DuPont, Local Motors, and the Composites Manufacturing and Simulation Center (CMSC) at Purdue worked together to advance process simulation capabilities for Additive Manufacturing (AM) and develop printable short fiber reinforced semi-crystalline engineering thermoplastics suitable for vehicle components. DuPont provided one candidate thermoplastic material, which was evaluated against the following three criteria: 1) Printability using extrusion additive manufacturing processes. 2) Suitability for vehicle applications based on mechanical coupon screening tests. 3) Predictive capability of process simulations. Indiana Manufacturing Institute provided modeling and simulation technology and access to Purdue’s lab scale AM printer. Local Motors provided mechanical property requirements and printed demonstration prototype components using their Thermwood Large Scale Additive Manufacturing (LSAM) printer. To meet the performance and cost requirements of the automotive industry, high fiber content semi-crystalline engineering materials are required. Printing experience and property data for a 50% by weight short glass fiber reinforced material were gathered. Further, material properties required for simulating the printing process with the glass-fiber reinforced material were characterized. Knowledge was acquired with regards to the processability and performance of this thermoplastic material. Predictions of part deformation and crystallinity level were verified against experimental observations. Any significant results other than verification of simulation, e.g., novel material identified here would be impactful.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Processing, physical metallurgy and creep of NiAl + Ta and NiAl + Nb alloys

Powder processed NiAl + Ta alloys containing 1, 2, and 4.5 at percent tantalum and NiAl + Nb alloys containing 1 and 2 at percent niobium were developed for improved creep properties. In addition, a cast alloy with 5 at percent tantalum was also studied. Hot extrusion parameters for processing alloys with 1 and 2 at percent of tantalum or niobium were designed. The NiAl + 4.5 at percent Ta alloy could be vacuum hot pressed successfully, even though it could not be extruded. All the phases in the multiphase alloys were identified and the phase transformations studied. The Ni2AlTa in NiAl + 4.5 at percent Ta alloy transforms into a liquid phase above 1700 K. Solutionizing and annealing below this temperature gives rise to a uniform distribution of fine second phase precipitates. Compressive creep properties were evaluated at 1300 K using constant load and constant velocity tests. In the higher strain rate region single phase NiAl + 1 at percent Ta and NiAl + 1 at percent Nb alloys exhibit a stress exponent of 5 characteristic of climb controlled dislocation creep. In slower strain rate regime diffusional creep becomes important. The two phase alloys containing 2 to 5 at percent Ta and 2 at percent Nb show considerable improvement over binary NiAl and single phase alloys. Loose dislocation networks and tangles stabilized by the precipitates were found in the as crept microstructure. The cast alloy which has larger grains and a distribution of fine precipitates shows the maximum improvement over binary NiAl.

Pathare, Viren M.↗
DOE OSTI2010

Modelling the Thermo-Mechanical Behavior of Magnesium Alloys during Indirect Extrusion

One of the basic metal forming process for semi-finished products is extrusion. Since extrusion involves complex thermo-mechanical and multiaxial loading conditions resulting in large strains, high strain rates and an increase in temperature due to deformation, a proper yield criterion and hardening law should be used in the numerical modelling of the process. A phenomenological model based on a plastic potential has been proposed that takes strain, strain rate and temperature dependency on flow behaviour into consideration. A hybrid methodology of experiment and finite element simulation has been adopted in order to obtain necessary model parameters. The anisotropy/asymmetry in yielding was quantified by tensile and compression tests of specimens prepared from different directions. The identification of the corresponding model parameters was performed by a genetic algorithm. A fully coupled thermo-mechanical analysis has been used in extrusion simulations for calculation of the temperature field by considering heat fluxes and heat generated due to plastic deformation. The results of the approach adopted in this study appeared to be successful showing promising predictions of the experiments and thus may be extended to be applicable to other magnesium alloys or even other hcp metals.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Direct Solid-State Conversion of Recyclable Metals and Alloys

This project is to develop and demonstrate the concept feasibility of a highly energy-efficient solid-state material synthesis process, friction stir extrusion (FSE) technology. Specifically, the project seeks to explore and demonstrate the feasibility to recycle metals, produce nano-particle dispersion strengthened bulk materials and/or nano-composite materials from powders, chips or other recyclable feedstock metals or scraps through mechanical alloying and thermo-mechanical processing in a single-step. In this study, we focused on metal recycling, producing nano-engineered wires and evaluating their potential use in future generation long-distance electric power delivery infrastructure. More comprehensive R&D on the technology fundamentals and system scale-up toward early-stage applications in two targeted “showcase” fields of use: nano engineered bulk materials and Al recycling will be considered and planned as part of Project Continuation Plan.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Evaluation of mixed #3–7 plastic waste from material recovery facilities (MRFs) in the United States

Plastic recycling rates are still low in the United States (U.S.), with less than 10% of municipal solid waste (MSW) plastic being recycled. Most unrecycled plastics are identified by Resin Identification Codes (RIC) from #3–7, which are commonly destined for landfill or waste-to-energy facilities (WTE). Therefore, the composition and quality of outbound bales containing #3–7 plastics were assessed to understand the potential to increase recycling rates. Three bales were sourced from three different Material Recovery Facilities (MRFs) located in the United States. Each bale was manually sorted and characterized for quality and performance via multiple plastic characterization techniques. Considerable differences in bale composition were observed between MRFs, which correlated with the technology used by each MRF in the sorting process. The differences were substantial in the residual levels of poly(ethylene terephthalate) (PET) and high-density polyethylene (HDPE), which are highly desired for mechanical recycling processes and not expected in #3–7 plastics bales. Traditional recycling processes including washing, extrusion, and injection molding of the sorted material were employed prior to the physical, thermal, and molecular characterization. Despite differences in bale composition by plastic type, some polymer properties were similar across MRFs. Here, this research suggests that landfill-diverted mixed plastic waste can be utilized in the mechanical recycling of currently unrecycled materials, as processes can be designed to work with consistent polymer properties. It also highlights the need to upgrade the sorting systems to prevent waste feedstocks, which can be recycled with current technologies, from contaminating other plastic streams or reach landfills.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Multi-material direct ink writing and co-sintering of gadolinium oxide – zirconium oxide components

Methods for fabrication of multi-material or functionally graded ceramic composite architectures are of interest for numerous applications. However, conventional co-sintering of multi-material ceramic parts is a challenge because differences in the sintering behavior of the two materials leads to interfacial strain and, ultimately, component failure. Direct ink writing (DIW) is an extrusion-based additive manufacturing process that excels at multi-material printing because multiple extrusion nozzles can be installed on the same gantry system. Furthermore, the use of DIW as a method to fabricate multi-material ceramic green bodies offers an additional variable for controlling and potentially matching sintering kinetics in the slurry formulation used for two dissimilar feedstocks. In the work documented in this manuscript, we explored two strategies to successfully co-sinter multi-material ceramic oxides: slurry optimization to match sintering kinetics and material gradients to step from one material to another. This manuscript also quantifies the allowable mismatch that avoids part cracking in solid solution forming multi-material systems and discusses best strategies to reduce mismatch during co-sintering. Inks composed of gadolinium oxide (Gd 2 O 3 ) and zirconium oxide (ZrO 2 ), a surrogate for uranium oxide (UO 2 ), were thermally matched, which resulted in a sintering mismatch reduction of over 10%. It was found that ~1% mismatch is tolerable during debind cycles and that ~5% mismatch is manageable during sintering cycles after slurry formulations are optimized to match the sintering behavior. Use of continuous gradients is shown to reduce sintering mismatch, although geometric resolution may be lost due to solid solution formation.

Snarr, Patrick L. [Oak Ridge National Laboratory (↗