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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
DOE OSTI2018

Microstructure Evolution and Microhardness Distribution of Copper Processed Using Multiple Passes of Elliptical Cross-Sectional Spiral Equal-Channel Extrusion

The aim of this work is to study the effect of six-pass elliptical cross-sectional spiral equal-channel extrusion (ECSEE) on the microstructure and performance of ultrafine-grained (UFG) copper. Equiaxed grains of average grain size of less than 1 μm are formed into shear bands in the low strain region of ECSEE deformed specimen. More homogeneous and equiaxed microstructure with high misorientation angles is obtained in the high strain. Moreover, the microstructure evolution of ECSEE-induced copper is a dynamic equilibrium process of shear deformation accompanying the interactions of high dislocation density, cellular structure and high-angle grain boundaries. The grain ECSEE refinement mechanism is described as the formation process of dislocations, cells, local grain sub-boundaries rotation and large angle grain restructure. The significantly non-uniform hardness distribution is consistent with the deformation behavior and microstructure refinement in the ECSEE-induced specimen. The homogeneity of microstructure and hardness improves as the ECSEE pass increases.

36 MATERIALS SCIENCE↗
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 OSTI2013

Changes in Moisture, Protein, and Fat Content of Fish and Rice Flour Coextrudates during Single-Screw Extrusion Cooking

Changes in proximate composition of fish and rice flour coextrudates like moisture, protein, and fat content were studied with respect to extrusion process v ariables like barrel temperature, x1 (100–200 degrees C); screw speed, x2 (70–110 rpm); fish content of the feed, x3 (5–45 percent); and feed moisture content, x4 (20–60 percent). Experiments were conducted at five levels of the process variables based on rotatable experimental design. Response surface models (RSM) were developed that adequately described the changes in moisture, protein, and fat content of the extrudates based on the coeff icient of determination (R2) values of 0.95, 0.99, and 0.94. ANOVA analysis indicated that extrudate moisture content was influenced by x4, protein content by x1 and x3, and fat content by x3 and x4 at P < 0.001. Trends based on response surf ace plots indicated that the x1 of about 200 degrees C, x2 of about 90 rpm, x3 of about 25%, and x4 of about 20% minimized the moisture in the extrudates. Protein content was maximized at x1 of 100 degrees C, x2 > 80 rpm, x3 of about 45 percent, and x4 > 50 percent, and fat content was minimized at x1 of about 200 degrees C, x2 of about 85–95 rpm, x3 < 15 percent, and x4 of about >50 percent. Optimized process variables based on a genetic algorithm (GA) for minimum moisture and fat content and maximum protein content were x1 = 199.86, x2 = 109.86, x3 = 32.45, x4 = 20.03; x1 = 199.71, x2 = 90.09, x3 = 15.27, x4 = 58.47; and x1 = 102.97, x2 = 107.67, x3 = 44.56, x4 = 59.54. The predicted values were 17.52 percent, 0.57 percent, and 46.65 percent. Based on the RSM and GA analy sis, extrudate moisture and protein content was influenced by x1, x3, and x4 and fat content by x2, x3, and x4.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2021

Large-scale additive manufacturing tooling for extrusion-compression molds

Carbon fiber reinforced polymer composites (CFPC) have been used in additive manufacturing (AM) due to both the high-strength-to-weight and superior-stiffness-to-weight ratios. CF AM is being considered for tooling applications. In AM, CFPCs are usually aligned along the deposition direction; however, it results in anisotropic thermal properties which affect the heat transfer and warpage of the final part. In this study, three male molds with different infill patterns were produced via the material extrusion additive manufacturing (EDF-AM) process. These include (a) 0°: infill pattern along the printing direction; (b) 90°: infill pattern perpendicular to the printing direction; and (c) 0°/90°: alternate layers along and perpendicular directions. The effect of the infill pattern on thermal conductivity was analyzed and observed that 0° infill (surface temperature: 79.2°C) had the highest conductivity; and 90° infill (surface temperature: 66.4°C) had the least.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The impact of infill percentage and layer height in small-scale material extrusion on porosity and tensile properties

We report material extrusion additive manufacturing is prone to introducing porosity within the structure due to the layer-by-layer construction using elliptical beads of material. This open porosity ultimately plays a role in determining the mechanical properties of printed parts. The shape, size, and amount of porosity within a printed part is influenced by a variety of factors, including nozzle diameter, infill percentage, layer height, raster orientation, and print speed. While several studies have investigated these and other parameters’ effects on mechanical performance and porosity, better understanding the interconnected relationships is crucial in balancing the various input parameters to achieve maximum strength. This work initially examined the influence of key print parameters (infill percentage and layer height) on the internal porosity of a printed Acrylonitrile Butadiene Styrene (ABS) part. Then, the print parameters and internal porosity were statistically correlated to final mechanical properties. Porosity was further classified as either open or closed to differentiate between connected voids in the mesostructure from isolated voids within the material itself. Mechanical performance increased with an increasing density and infill percentage, displaying a 224 % increase in elastic modulus and a 150 % increase in ultimate tensile strength. The contribution of layer height was found to be conditional upon the infill percentage.

3D Printing↗
DOE OSTI2022

Additive manufacturing of continuous carbon fiber-reinforced SiC ceramic composite with multiple fiber bundles by an extrusion-based technique

Due to the high cost, complex preparation process and difficulty in structural design, the traditional methods for carbon fiber-reinforced SiC ceramic composite preparation have great limitations. This paper presents a technique for the additive manufacturing multiple continuous carbon fiber bundle-reinforced SiC ceramic composite with core-shell structure using an extrusion-based technique. A conventional nozzle system was modified to print simultaneously a water-based SiC paste with continuous carbon fibers. Different levels of binder contents were investigated to optimize the stickiness, viscosity, thixotropy and viscoelasticity of the paste. After sintering, SiC whiskers were generated on the surface of fiber, which is conjectured to be due to the reaction between SiO and carbon fiber at high temperature. The continuous carbon fiber-reinforced SiC ceramic composite exhibited non-brittle fracture. In conclusion, the flexural strength of the additively manufactured Cf/SiC composites improved from 162 MPa with no fiber bundles to a maximum of 219 MPa with three fiber bundles.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Processing and mechanical characterization of short carbon fiber-reinforced epoxy composites for material extrusion additive manufacturing

Fiber-reinforced polymer composites have been extensively utilized in recent years as feedstock materials for material extrusion additive manufacturing (AM) processes to improve strength, stiffness, and functionality of printed parts over unfilled printed polymers. However, the widespread adoption of AM of fiber-reinforced polymer composites requires a deeper understanding of the process-structure-property relationships in printed components, and such relationships are not well understood yet. Fiber length is critically important to the mechanical performance of short fiber composites, but very few studies to-date have focused on how the fiber length distribution (FLD) evolves during processing of composite feedstocks and how this evolution affects printing behavior and mechanical properties in 3D-printed composites. Here, FLD is measured for carbon fiber reinforced epoxy composites over a wide range of ink compositions and shear mixing times, and the distributions are fit with a Weibull-type distribution function. The effects of FLD on the tradeoff between ink processability, ink rheology, printing behavior and mechanical properties are investigated. Furthermore, the effects of printing parameters (nozzle size and print speed) on mechanical anisotropy and fiber orientation distribution (FOD) in printed composites are explored. Mechanical properties of printed composites are characterized via 3 pt-flexural testing, and microstructure is investigated using optical and scanning electron microscopy (SEM), and x-ray computed tomography. Finally, the fitted Weibull parameters are fed into a composite model that incorporates FLD and FOD, and model predictions are found to be in excellent agreement with experimental observations.

3D printing↗
DOE OSTI2022

Interlayer fusion bonding of semi-crystalline polymer composites in extrusion deposition additive manufacturing

This work focuses on the evolution of interlayer fracture toughness properties of fiber-reinforced, semi-crystalline polymers in the extrusion deposition additive manufacturing (EDAM) process. Further, this work bridges the gap between the additive process conditions (time-temperature history) and the effective layer-to-layer fracture properties developed within a printed component. This is the first step to predict delamination that can occur during printing, during cooling to room temperature after printing, and during service performance of an additively manufactured geometry. A phenomenological model is developed for fusion bonding of semi-crystalline polymer matrix composites by coupling the interdiffusion of polymer chains with the evolution of polymer crystallinity. While the interdiffusion is captured by reptation theory of polymer dynamics, the evolution of crystallinity is modeled by phenomenological crystallization kinetics and crystal melting dynamics. Further, a methodology is developed to determine the critical strain energy release rate, G IC of the interlayer interface and experiments are conducted utilizing the double cantilever beam fracture test geometry. In conclusion, predictions of GIC as a function of thermal history are compared with experiments.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Friction extrusion of ODS copper rod made from powder

Meters-long oxide dispersion strengthened copper rods were manufactured directly from powder by a single-step process, called friction extrusion. The average grain size was 880 nm, which was refined 40 times from powder precursor due to extensive shear deformation. Meanwhile, the average size of alumina particles was 60 nm which retains a decent oxide dispersion strengthening. Here, mechanical properties, including hardness, tensile strength, and ductility, were tested and found to have better or similar values than conventional sintered-then-extruded oxide dispersion strengthened copper materials. The presented technique promises a convenient avenue for the fabrication of oxide dispersion strengthened copper from powder.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Fabrication of thin-walled tubes from alloy 602 CA using shear assisted processing and extrusion

Thin-walled tube is usually produced seamlessly via an expensive multi-step process or via welding of thin sheets but at reduced performance. To overcome the current process and performance inefficiencies, advanced manufacturing methods need to be investigated. In this investigation, shear assisted processing and extrusion (ShAPE) was used to fabricate thin-walled Inconel 602 tube in a single-step. Tubes measuring 0.83 m length with a 12 mm outer diameter and 1 mm wall thickness were fabricated with an average surface roughness, Ra of 1.6 µm and Rz of 15 µm. Tensile testing of tubes in the as-fabricated condition showed strength increases of 4-35% over current offerings while maintaining or improving elongation. Electron microscopy analysis revealed the recrystallized microstructure with refined inter- and intra-granular carbides. Preliminary results obtained in this investigation shows the feasibility of producing thin-wall high temperature tube in single-step via ShAPE. This achievement marks a significant step towards manufacturing larger diameter nickel alloy tubes for the U.S. Department of Energy’s Waste Treatment and Immobilization Plant.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP)

Thermal stability of the ultra-fine grained (UFG) microstructure of magnesium AZ31 alloy was investigated. UFG microstructure was achieved by a combined two-step severe plastic deformation process: the extrusion (EX) and subsequent equal-channel angular pressing (ECAP). This combined process leads to refined microstructure and enhanced microhardness. Specimens with UFG microstructure were annealed isochronally at temperatures 150–500 °C for 1 h. The evolution of microstructure, mechanical properties and dislocation density was studied by electron backscatter diffraction (EBSD), microhardness measurements and positron annihilation spectroscopy (PAS). The coarsening of the fine-grained structure at higher temperatures was accompanied by a gradual decrease of the microhardness and decrease of dislocation density. Mechanism of grain growth was studied by general equation for grain growth and Arrhenius equation. Activation energies for grain growth were calculated to be 115, 33 and 164 kJ/mol in temperature ranges of 170–210 °C, 210–400 °C and 400–500 °C (443–483 K, 483–673 K and 673–773 K), respectively. - Highlights: • Microhardness of UFG AZ31 alloy decreases with increasing annealing temperature. • This fact has two reasons: dislocation annihilations and/or grain growth. • The activation energies for grain growth were calculated for all temperature ranges.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructure and mechanical properties development of micro channel tubes in extrusion, rolling and brazing

Highlights: • Rolling and brazing greatly affect the properties of micro-channel tubes (MCTs). • The properties of MCTs are investigated by the evolution of the microstructure. • Strength is decreased by 47% at 5%-rolling reduction ratio and 3-minute brazing. • Ductile fracture mode is observed by OM at failure of MCTs under inner pressure. - Abstract: In addition to extrusion, the post-processing of rolling and brazing has significant effect on the mechanical properties of multi-port tubes. The aluminum micro channel tubes, especially the seam welding zone in the internal webs, are investigated in terms of mechanical tests, microstructure characterization, and finite element analysis. The effect of the post-process of rolling are quantified by varying amount of rolling reduction ratios. Tensile strength and pressure bearing capacity are determined by tensile tests and burst pressure tests, respectively. The evolution of the microstructure within the seam wielding zone is characterized by Electron backscattered diffraction (EBSD) and optical microscopy (OM). The fracture profile observed by OM indicates ductile fracture mode. The pressure bearing capacity is reduced by ~47% at 5% reduction ratio of rolling followed by 3-minute brazing, where largest grains are obtained due to abnormal grain growth.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Microstructure evolution, enhanced aging kinetics, and mechanical properties of AA7075 alloy after friction extrusion

In the present study we utilized Friction Extrusion (FE) a solid phase processing technique to produce fully consolidated dense 5 mm rods of AA7075 alloy. The combination of large shear stresses and temperatures at the tool-billet interface during the FE process resulted in the formation of dynamically recrystallized ~2.0 μm equiaxed grains and fine uniformly distributed stable η (MgZn 2 ) precipitates ~25–100 nm in size. Formation of such a microstructure resulted in lower solutionizing temperature and times (flash annealing) as compared to the conventionally extruded counterparts. Here we demonstrate for the first time that the solutionizing times for the T6 heat treatment of AA7075 can be reduced by three times using this FE process. In addition to being an energy efficient process, FE also serves to improve the performance of AA7075 alloys by retaining their strength while enhancing the ductility of the material. The tensile data for samples that were flash annealed and artificially aged after FE processing showed exceptional increase in ultimate tensile strength by over 19% and yield strength by over 59%, compared with an as-FE-processed sample.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Ondansetron can enhance cisplatin-induced nephrotoxicity via inhibition of multiple toxin and extrusion proteins (MATEs)

The nephrotoxicity limits the clinical application of cisplatin. Human organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins (MATEs) work in concert in the elimination of cationic drugs such as cisplatin from the kidney. We hypothesized that co-administration of ondansetron would have an effect on cisplatin nephrotoxicity by altering the function of cisplatin transporters. The inhibitory potencies of ondansetron on metformin accumulation mediated by OCT2 and MATEs were determined in the stable HEK-293 cells expressing these transporters. The effects of ondansetron on drug disposition in vivo were examined by conducting the pharmacokinetics of metformin, a classical substrate for OCTs and MATEs, in wild-type and Mate1−/− mice. The nephrotoxicity was assessed in the wild-type and Mate1−/− mice received cisplatin with and without ondansetron. Both MATEs, including human MATE1, human MATE2-K, and mouse Mate1, and OCT2 (human and mouse) were subject to ondansetron inhibition, with much greater potencies by ondansetron on MATEs. Ondansetron significantly increased tissue accumulation and pharmacokinetic exposure of metformin in wild-type but not in Mate1−/− mice. Moreover, ondansetron treatment significantly enhanced renal accumulation of cisplatin and cisplatin-induced nephrotoxicity which were indicated by increased levels of biochemical and molecular biomarkers and more severe pathohistological changes in mice. Similar increases in nephrotoxicity were caused by genetic deficiency of MATE function in mice. Therefore, the potent inhibition of MATEs by ondansetron enhances the nephrotoxicity associated with cisplatin treatment in mice. Potential nephrotoxic effects of combining the chemotherapeutic cisplatin and the antiemetic 5-hydroxytryptamine-3 (5-HT{sub 3}) receptor antagonists, such as ondansetron, should be investigated in patients. - Highlights: • Nephrotoxicity significantly limits clinical use of the chemotherapeutic cisplatin. • The antiemetic ondansetron is frequently co-administrated with cisplatin. • Ondansetron was here demonstrated as a potent inhibitor of MATE transporters. • Ondansetron enhanced cisplatin nephrotoxicity likely via Mate1 inhibition in mice. • Ondansetron may increase patient risk of nephrotoxicity in cisplatin chemotherapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Multidrug and toxin extrusion proteins mediate cellular transport of cadmium

Cadmium (Cd) is an environmentally prevalent toxicant posing increasing risk to human health worldwide. As compared to the extensive research in Cd tissue accumulation, little was known about the elimination of Cd, particularly its toxic form, Cd ion (Cd{sup 2+}). In this study, we aimed to examine whether Cd{sup 2+} is a substrate of multidrug and toxin extrusion proteins (MATEs) that are important in renal xenobiotic elimination. HEK-293 cells overexpressing the human MATE1 (HEK-hMATE1), human MATE2-K (HEK-hMATE2-K) and mouse Mate1 (HEK-mMate1) were used to study the cellular transport and toxicity of Cd{sup 2+}. The cells overexpressing MATEs showed a 2–4 fold increase of Cd{sup 2+} uptake that could be blocked by the MATE inhibitor cimetidine. A saturable transport profile was observed with the Michaelis-Menten constant (K{sub m}) of 130 ± 15.8 μM for HEK-hMATE1; 139 ± 21.3 μM for HEK-hMATE2-K; and 88.7 ± 13.5 μM for HEK-mMate1, respectively. Cd{sup 2+} could inhibit the uptake of metformin, a substrate of MATE transporters, with the half maximal inhibitory concentration (IC{sub 50}) of 97.5 ± 6.0 μM, 20.2 ± 2.6 μM, and 49.9 ± 6.9 μM in HEK-hMATE1, HEK-hMATE2-K, and HEK-mMate1 cells, respectively. In addition, hMATE1 could transport preloaded Cd{sup 2+} out of the HEK-hMATE1 cells, thus resulting in a significant decrease of Cd{sup 2+}-induced cytotoxicity. The present study has provided the first evidence supporting that MATEs transport Cd{sup 2+} and may function as cellular elimination machinery in Cd intoxication. - Highlights: • Cadmium is an environmentally prevalent toxicant. • Little was known regarding the elimination and detoxification of cadmium. • Cadmium ion is here demonstrated as a substrate of MATE transporters. • MATEs may function as cellular elimination machinery in cadmium detoxification.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Improved properties of recycled polypropylene by introducing the long chain branched structure through reactive extrusion

Highlights: • A novel approach is applied to modify recycled PP. • Long chain branched structure is introduced onto recycled PP. • The structural change of recycled PP is determined by FTIR, DSC and rheology. • The impact strength of recycled PP is obviously improved. • Inorganic fillers have no effect on the modification of recycled PP. - Abstract: An approach originated from preparing long chain branched polypropylene (PP) was applied to modify the properties of recycled PP that involved reactive extrusion to introduce a branched chain structure onto recycled PP under the assistance of chemical reaction between maleic anhydride (MAH) monomer and glycidyl methacrylate (GMA) grafts. The results from Fourier transformed infrared spectroscopy (FTIR) indicated the reaction took place during melt mixing, and the intensity of ester increased with increasing amount of MAH. Several rheological plots including complex viscosity, storage modulus, loss modulus, loss tangent and Cole-Cole plot were used to investigate the rheological properties of recycled PP and modified PP with MAH, which indicated an additional longer relaxation time that was not shown in recycled PP. The effects of branched structure on melting and crystallization behaviors were also investigated, demonstrating the branched chains acted as nucleating agent. Moreover, the branched structure of modified samples gave rise to enhance mechanical properties, especially, the higher impact strength compared with recycled PP.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Terahertz inline wall thickness monitoring system for plastic pipe extrusion

Conventional and commercially available inline wall thickness monitoring systems for pipe extrusion are usually based on ultrasonic or x-ray technology. Disadvantages of ultrasonic systems are the usual need of water as a coupling media and the high damping in thick walled or foamed pipes. For x-ray systems special safety requirements have to be taken into account because of the ionizing radiation. The terahertz (THz) technology offers a novel approach to solve these problems. THz waves have many properties which are suitable for the non-destructive testing of plastics. The absorption of electrical isolators is typically very low and the radiation is non-ionizing in comparison to x-rays. Through the electromagnetic origin of the THz waves they can be used for contact free measurements. Foams show a much lower absorption in contrast to acoustic waves. The developed system uses THz pulses which are generated by stimulating photoconductive switches with femtosecond laser pulses. The time of flight of THz pulses can be determined with a resolution in the magnitude of several ten femtoseconds. Hence the thickness of an object like plastic pipes can be determined with a high accuracy by measuring the time delay between two reflections on materials interfaces e.g. at the pipe's inner and outer surface, similar to the ultrasonic technique. Knowing the refractive index of the sample the absolute layer thickness from the transit time difference can be calculated easily. This method in principle also allows the measurement of multilayer systems and the characterization of foamed pipes.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Thermal Conductivity Measurement of Extrusion-Printed Silver Using Modulated Photothermal Radiometry

Flexible printed electronics is a rapidly growing field with applications in conformal and flexible devices. However, the physical properties of the films created by many state-of-the-art printing methods become highly dependent on printing parameters, resulting in varying thermal properties often differing significantly from their bulk ink components. To understand the influence of the printing process, we build upon our previous work, where a noncontact optical technique, known as modulated photothermal radiometry (MPTR), was used to measure the thermal conductivity of aerosol-jet-printed thin films. In this work, we use the method to study the thermal properties of extrusion-printed silver on glass and alumina substrates. A noise-resistant data analysis fitting technique is applied using a 2-D heat transfer model. Here, the thermal conductivity measurement is validated using the Weidemann-Franz (WF) relationship from measured electrical conductivity values.

42 ENGINEERING↗