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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Ultrasonic imaging of textured alumina

Ultrasonic images representing the bulk attenuation and velocity of a set of alumina samples were obtained by a pulse-echo contact scanning technique. The samples were taken from larger bodies that were chemically similar but were processed by extrusion or isostatic processing. The crack growth resistance and fracture toughness of the larger bodies were found to vary with processing method and test orientation. The results presented here demonstrate that differences in texture that contribute to variations in structural performance can be revealed by analytic ultrasonic techniques.

Stang, David B.↗
NASA NTRS1990

Ultrasonic imaging of textured alumina

Ultrasonic images representing the bulk attenuation and velocity of a set of alumina samples were obtained by a pulse-echo contact scanning technique. The samples were taken from larger bodies that were chemically similar but were processed by extrusion or isostatic processing. The crack growth resistance and fracture toughness of the larger bodies were found to vary with processing method and test orientation. The results presented here demonstrate that differences in texture that contribute to variations in structural performance can be revealed by analytic ultrasonic techniques.

Stang, D. B.↗
DOE OSTI2020

Ultrafine-grained Al-Mg-Zr Alloy Processed by Shear-Assisted Extrusion with High Thermal Stability

Shear-assisted processing and extrusion (ShAPE) is used to consolidate Al-4.2Mg-1.6Zr-0.25Si-0.1Fe (wt.%) powders. The extruded alloy exhibits: (i) near-zero porosity; (ii) an attractive combination of tensile yield strength (~220 MPa), ultimate strength (330 MPa) and elongation (>20%); and (iii) excellent thermal stability at 400 ºC. The ultra-fine grain size in the gas-atomized powders – created and stabilized by primary L12-Al3Zr submicron precipitates - is maintained after consolidation and subsequent exposure at 400 ºC, contributing twice as much to strength as Mg in solid-solution. Electron microscopy reveals the microstructure of the L12-Al3Zr precipitates, and other precipitates (Mg2Si and Al3Fe) and dispersoids (oxides).

ShAPE, Friction Extrusion, aluminum powder, Shear ↗
NASA NTRS2006

Manufacture of Regularly Shaped Sol-Gel Pellets

An extrusion batch process for manufacturing regularly shaped sol-gel pellets has been devised as an improved alternative to a spray process that yields irregularly shaped pellets. The aspect ratio of regularly shaped pellets can be controlled more easily, while regularly shaped pellets pack more efficiently. In the extrusion process, a wet gel is pushed out of a mold and chopped repetitively into short, cylindrical pieces as it emerges from the mold. The pieces are collected and can be either (1) dried at ambient pressure to xerogel, (2) solvent exchanged and dried under ambient pressure to ambigels, or (3) supercritically dried to aerogel. Advantageously, the extruded pellets can be dropped directly in a cross-linking bath, where they develop a conformal polymer coating around the skeletal framework of the wet gel via reaction with the cross linker. These pellets can be dried to mechanically robust X-Aerogel.

Leventis, Nicholas↗
DOE OSTI2020

Process Intensification for Nanocomposite Aluminum Extrusions: CRADA 411 (Final Report)

The project evaluated the feasibility of using Shear Assisted Processing and Extrusion (ShAPE) for the fabrication of extrusions with a diameter of 0.5” and higher from an Al-alloy powder feedstock that contains nanoscale second phases for achieving enhanced elevated temperature strength. PNNL has previously extruded 0.2” diameter rods with high strength aluminum alloy powder Al-12.4TM. This project aimed to scale the process up to a diameter of 1.0” at a length of >24” while retaining the excellent mechanical properties achieved for the 0.2” diameter rods. As part of the project, extrusion dies were fabricated with various design features. As an example, scroll features on the tool die face was introduced to enhance powder mixing, and reduce extrusion load. Varying extrusion ratios were used to obtain better microstructural homogeneity. Use of tool design features together with the optimization of process parameters helped in the fabrication of extrusions that were up to 48” long with a diameter of 0.5” using Al-12.4 TM powder feedstock in a two-step process involving cold compaction followed by extrusion. Extrusions with a diameter of 1.0” could also be fabricated, but limitations on the extent of consolidation were experienced as a result of the torque and ram force capacity of the current ShAPE machine.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Selective Deposition and Fusion of AISI 316L: An Additive Manufacturing Process for Space Environments via Direct Ink Writing and Laser Processing

Unlocking the potential of additive manufacturing (AM) for space exploration hinges on overcoming key challenges, notably the ability to manufacture or repair parts on-site during exploration missions with consideration of quality, feedstock utilization, and challenges involved in microgravity environments. While there are multiple efforts to investigate the use of existing metal AM processes such as powder bed fusion (PBF), directed energy deposition (DED), and filament-based material extrusion, each process comes with a different set of challenges in space environments. Here, in this work, we introduce a new AM method that integrates the benefits of direct ink writing (DIW) to selectively deposit metallic pastes with laser-based processing to locally debind and subsequently melt and fuse metal powder, layer by layer, enabling the manufacturing of AISI 316L samples with densities exceeding 99.0%. The impact of process parameters on single-track dimensions, surface morphology, and porosity was characterized. The efficacy of laser debinding was assessed via secondary-ion mass spectrometry, permitting the carbon content to be estimated at 0.0152%, which is safely below the acceptable limit (0.03 wt%) for AISI 316L.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Rheological survey of carbon fiber-reinforced high-temperature thermoplastics for big area additive manufacturing tooling applications

Carbon fiber (CF)-reinforced thermoplastic composites have been widely used in different structural applications due to their superior thermal and mechanical properties. The big area additive manufacturing (BAAM) system, developed at Oak Ridge National Laboratory’s Manufacturing Demonstration Facility, has been used to manufacture several composite components, demonstration vehicles, molds, and dies. These components have been designed and fabricated using various CF-reinforced thermoplastics. In this study, the dynamic rheological and mechanical properties of a material commonly used in additive manufacturing, 20 wt% CF-acrylonitrile butadiene styrene (ABS), as well as three CF-reinforced high-temperature polymers, 25 wt% CF-polyphenylsulfone (PPSU), 35 wt% CF-polyethersulfone (PES), and 40 wt% CF-polyphenylene sulfide (PPS), used to print molds were investigated. The viscoelastic properties, namely storage modulus, loss modulus, tan delta, and complex viscosity, of these composites were studied, and the rheological behavior was related to the BAAM extrusion and bead formation process. The results showed 20 wt% CF-ABS and 40 wt% CF-PPS to display a more dominant elastic component at all frequencies tested while 25 wt% CF-PPSU and 35 wt% CF-PES have a more dominant viscous component. This viscoelastic behavior is then used to inform the deposition and bead formation process during extrusion on the BAAM system.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Microstructural and micro-mechanical analysis of 14YWT nanostructured Ferritic alloy after varying thermo-mechanical processing paths into tubing

Microstructural analyses and micro-pillar compression were conducted on 14YWT nanostructured ferritic alloy (NFA) to compare different processing pathways: hydrostatic extrusion and Pilger processing with varying annealing temperatures into thin walled tubing, and after hot extrusion and cross-rolling into a plate. Hydrostatic extrusion at 815 °C resulted in the smallest grain sizes and highest yield strength of 1.20 GPa. Pilger processing with annealing at 800 °C had fine grained regions and bands of coarse grains, leading to a large variation in yield strength of 0.9–1.40 GPa. Higher annealing temperatures of 1200 °C after pilger processing significantly increased the grain size and lowered the yield strength to 1.01 GPa. These tubes showed a stronger (111) crystallographic texture in the normal direction and elongated grains in the extrusion direction. Characterization of the nano-oxides using TEM reveals more numerous, smaller oxides present in tubing processed at lower temperatures. Overall, this work shows NFA tubing after hydrostatic extrusion and pilger processing can lead to fine grained microstructures and texturing leading to higher yield strengths at lower annealing temperatures (e.g. 800 °C).

14YWT↗
DOE OSTI2021

New Extrusion Method is Taking ShAPE

PNNL’s patented Shear Assisted Processing and Extrusion (ShAPE™) includes a novel extrusion machine, tooling, and associated processing techniques that delivers high-performance metal alloys for a wide range of market needs. ShAPE is a technique for manufacturing wire, bar, and tubular extrusions with unprecedented properties and manufacturing advantages compared to conventional extrusion. In a single step, ShAPE extrudes metal powder, flake, chip, and ingot directly into products with properties that cannot be achieved by conventional means. ShAPE delivers better products, because it uniquely mixes and deforms the metal feedstocks in their solid form without melting them, dramatically improving product properties and the energy efficiency of production.

Joshi, Vineet V.↗
DOE OSTI2019

Microstructure and Mechanical Properties of Copper Billets Fabricated by the Repetitive Extrusion and Free Forging Process

In the present study, with the aim of obtaining a weakened texture, grain refinement and improved mechanical properties, copper billets were successfully fabricated using the severe plastic deformation method of repetitive extrusion and free forging (REFF) without using any additional tools or devices. The evolution of the microstructure, texture and mechanical behavior of the ultrafine grain copper billets over an increasing number of REEF cycles was also systematically studied. Our results show that the effective strain per REFF process was ε = 2.35. After two cycles of REFF process, the sum effective strain became ε = 4.7, leading to high efficiency of grain refinement. The grain size was refined from 50 to 0.8 μm; the yield strength was increased to 462 MPa, and we obtained a weakened texture in the pure copper billets. By increasing the number of cycles, the grain refinement ability was decreased, and the texture was thus strengthened further. Therefore, two cycles of REFF were a reasonable process for producing ultrafine-grained copper billets.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Manufacture aluminum alloy tube from powder with a single-step extrusion via ShAPE

Mechanical performance of aluminum in terms of strength, wear and corrosion resistance, especially high-temperature strength has been shown to improve with the addition of transition metal (TM) elements of Fe, Cr, and Ti. However, these feedstock materials occur as powders. As such, the traditional fabrication process is complex and expensive because it requires multiple procedures and consumes considerable energy. This study developed Shear Assisted Processing and Extrusion (ShAPE) as a single-step process that manufactures tubes directly from Al-TM powders obtained via gas atomization. Meter-long Al-TM alloy tubes are extruded from powders with different processing conditions. The ShAPE tubes have very low porosity and the average density is 2.94 kg/cm 3 , which is equal to or higher than parts fabricated by hot extrusion and sintering. The powder-to-tube fabrication process was revealed and discussed by examining the microstructural evolution. The Vickers hardness of ShAPE tubes ranges from 110 to 140 HV through wall thickness and at different extrusion speeds. The variation in hardness was correlated with the extent of refinement of intermetallics and attributed to the shear deformation per unit extrusion length. Energy cost analysis shows that ShAPE save ~60% energy compared to the conventional sintering and extrusion processes. Results indicate ShAPE is a low-cost, high-efficiency manufacturing process for producing tubes from metallic powders.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Additive manufacturing and mechanical characterization of high density fully stabilized zirconia

Mechanical properties of additively manufactured 8 mol% yttria-stabilized zirconia (8YSZ) parts were extensively studied for the first time. A novel freeform extrusion fabrication process, called Ceramic On-Demand Extrusion (CODE), was employed to deposit an aqueous viscous suspension (~50 vol% solids loading) of fully stabilized zirconia powder in a layer-by-layer fashion. Each layer was exposed to infrared radiation after deposition to attain partial solidification due to drying. Before exposure, the layer was surrounded by oil to preclude non-uniform evaporation, which could cause warpage and crack formation. After the fabrication process was completed, the parts were humid-dried in an environmental chamber and densified by sintering under atmospheric pressure. Here standard test methods were employed to examine the properties of sintered parts including density, Vickers hardness, fracture toughness, Young's modulus, and flexural strength. Microstructural evaluation was also performed to observe the microstructural morphology and measure grain size. The results indicate that the properties of 8YSZ parts produced by the CODE process match those obtained by conventional fabrication techniques.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Differential Property Prediction: A Machine Learning Approach to Experimental Design in Advanced Manufacturing

Advanced manufacturing techniques have enabled the production of materials with state-of-the-art properties. In many cases however, the development of physics-based models of these techniques lags behind their development in the lab. This means that material and process development proceeds largely via trial and error. This is sub-optimal since experiments are cost-, time-, and labor-intensive. In this work we propose a machine learning framework, differential property classification (DPC), which enables an experimenter to leverage machine learning's unparalleled pattern matching capability to pursue data-driven experimental design. DPC takes two possible experiment parameter sets and outputs a prediction of which will produce a material with a more desirable property specified by the operator. We demonstrate the success of DPC on AA7075 tube manufacturing process and mechanical property data using shear assisted processing and extrusion (ShAPE), an emerging solid phase processing technology. We show that by focusing on the experimenter's need to choose between multiple candidate experimental parameters, we can reframe the challenging regression task of predicting material properties from processing parameters, into a classification task on which machine learning models can achieve good performance.

advanced manufacturing, machine learning, ShAPE↗
DOE OSTI2024

Aluminum Ultra-conductors for Energy-Efficient Aerospace Busbar Applications (Abstract)

In this project, we will develop aluminum ultra-conductors with graphene additives demonstrating enhanced electrical conductivity at 90 °C compared to electric grade aluminum alloy AA1100 (43% IACS at 90 °C). While ultra-conductivity has been developed in copper and copper alloys, it is yet to be reported extensively in aluminum-based materials. This project will scale initial work done at PNNL on aluminum ultra-conductors using shear-assisted processing and extrusion (ShAPETM), a novel solid phase processing technique. Ultra-conductors are an emerging class of composites, comprised of a metal substrate with small quantities of nanocrystalline additives such as graphene or carbon nanotubes that demonstrate enhanced conductivity at relevant operating temperatures. Aluminum ultra-conductors can improve efficiency and power density while reducing the demand for copper in a wide range of applications, such as power transmission cables and electric motors. Busbars are an important component in aerospace systems that require lightweight and high-current power distribution including both future electric vertical take-off and landing (eVTOL) aircrafts and current aircraft electrical systems. We will accelerate aluminum ultra-conductor composite formulation development using combinatorial synthesis and testing methods aided by process/microstructure modeling, developed previously at PNNL. Eaton will test the properties of the ShAPE aluminum ultra-conductor feedstock (used to make the busbars) in relevant operating conditions (20 – 90 °C), predict the improvement in busbar performance when manufactured with ultra-conductors over commercial conductors (such as AA1100), and perform technoeconomic analysis to evaluate the potential for commercialization of ShAPE aluminum ultra-conductors. The project is expected to have a budget of $\$375$K, with $\$300$K in federal funding and $\$75$K in-kind cost-share contribution from Eaton over a period of performance of 24 months. Of the $\$300$K of federal funds, $\$140$K is allocated for CRADA activities that generate intellectual property (IP), and the remaining $\$160$K is reserved for modeling, material testing, characterization, travel, and reporting-related activities.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Assessment of asymmetrical rheological behavior of cementitious material for 3D printing application

Among the multiplicity of construction methods based on digital concrete technologies, the most common one remains the extrusion-based process. Two opposed strategies have been developed in order to print a concrete structure using extrusion: the first one emphasizes the ease-of-pumping of material which is massively accelerated to ensure the stability of the structure, when leaving the extruder; the second one uses a firm mortar able to sustain the own weight of the structure during the printing, without requiring any accelerator. Both methods have their pros and cons and don't imply the same rheological requirements. Most of the recent literature assumes that both types of material (fluid and firm) follow the same trend of behavior and obey to the Von Mises plasticity criterion, while it has been demonstrated that firm cement-based materials can exhibit a pressure dependent behavior. Moreover, rheological study is mainly based on shear rheometry, while the extrusion-based printing process requires a description of the rheological behavior in compression to predict the global stability of the structure, and in tension to prevent cracks formation. This paper investigates the fresh behavior of cement paste and mortar under different solicitations (shear, compression, tension) for different water to cement ratios. The analysis of these results allows to describe the transition between a ductile fluid material (symmetrical in tension and compression) that obeys to a Von Mises plasticity criterion, and a brittle and firm material (asymmetrical in tension and compression) that requires a pressure dependent plasticity criterion in order to predict its strength under a given solicitation.

36 MATERIALS SCIENCE↗
NASA NTRS1981

Applications of polymer extrusion technology to coal processing

Upon heating, many of the middle-aged bituminous coals exhibit a plasticity very similar to polyethylene for a few minutes. Plastic coal can be extruded, pelletized or molded using common plastics technology and equipment. Investigations concerning the plastic state of coals are conducted with the objective to develop techniques which will make useful commercial applications of this property possible. Experiments which show the characteristics of plastic-state coal are discussed, and problems related to a continuous extrusion of coal are considered. Probably the most significant difference between the continuous extrusion of coal and the extrusion of a thermoplastic polymer is that volatiles are continuously being released from the coal. Attention is given to aspects of dragflow, solids feeding, and melt pumping. Application potentials for plastic coal extrusion might be related to coal gasification, direct liquefaction, and coal combustion.

Lewis, D. W.↗
DOE OSTI2024

Non-Rare Earth Magnesium Bumper Beams

Magna will team with the Pacific Northwest National Laboratory (PNNL) to develop Shear Assisted Processing and Extrusion (ShAPE™) of rectangular and multi-zoned extrusion profiles using non-RE Mg. It is envisioned that the ShAPE™ process, developed during this project for non-circular profiles, will serve as the foundation for fabrication of full-scale bumper beams of the future where near net-shapes are extruded directly from castings in a single step, without the need for costly rare earth additives. In this project, the ShAPE™ process will be developed for a rectangular profile measuring 1” x 2” with a 0.06” wall thickness. Successful extrusion of rectangular cross sections is a critical step along the path toward profiles with multiple zones. With the process established for a rectangular profile, the project will then make advancements toward multi-zoned cross sections. A magnesium alloy bumper beam offers a 35% weight savings compared to aluminum alloys and 60% compared to high strength steels. The bumper beam was chosen as the first component to target because the geometry can have a fairly simple 0.6-0.12 inch wall/web thickness, generally compatible with PNNL’s knowledge base and equipment capability surrounding ShAPE™. The bumper component offers commercial value by providing mass reduction in the front of the vehicle along with ride and handling benefit. PNNL has demonstrated the ability to ShAPE™ process non-RE Mg tubing with high strength, ductility and energy absorption. It has been shown that ShAPE™ extruded ZK60 and Mg2Si tubing with 0.30 inch diameter and 0.03 inch wall thickness have similar energy absorption to AA6061-T6. This is due to significant grain refinement, breakdown and dispersion of second phases, and the ability to eliminate anisotropy in compressive/tensile strength by aligning texture 45 degrees to the extrusion axis. Scalability of the ShAPE™ process has been demonstrated in ZK60 by fabricating 2.0 inch diameter tubing with 0.06 and 0.12 inch wall thicknesses having concentricity as tight as 1.3%. These tubes exhibit an ultimate tensile strength of 260-300 MPa and room temperature ductility of >20% parallel, perpendicular and 45 degrees to the extrusion axis. Aluminum bumpers represent approximately 54% of the NA light vehicle market. If the research effort is successful, providing a 30% mass reduction at equal cost relative to aluminum bumpers, it is anticipated that 25% market penetration would be realized over the next 5 year and 50% market share by 2030. 100% of the aluminum automotive bumpers are sourced from the tier network, providing resourcing opportunity based on equal performance, reduced mass and cost equivalent lower than aluminum bumpers. Due to the relatively low vehicle content, magnesium components are currently shredded and 100% recycled with aluminum content in the US, presenting a positive life cycle impact.

42 ENGINEERING↗