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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

3D-printed sheet jet for stable megahertz liquid sample delivery at X-ray free-electron lasers

X-ray free-electron lasers (XFELs) can probe chemical and biological reactions as they unfold with unprecedented spatial and temporal resolution. A principal challenge in this pursuit involves the delivery of samples to the X-ray interaction point in such a way that produces data of the highest possible quality and with maximal efficiency. This is hampered by intrinsic constraints posed by the light source and operation within a beamline environment. For liquid samples, the solution typically involves some form of high-speed liquid jet, capable of keeping up with the rate of X-ray pulses. However, conventional jets are not ideal because of radiation-induced explosions of the jet, as well as their cylindrical geometry combined with the X-ray pointing instability of many beamlines which causes the interaction volume to differ for every pulse. This complicates data analysis and contributes to measurement errors. An alternative geometry is a liquid sheet jet which, with its constant thickness over large areas, eliminates the problems related to X-ray pointing. Since liquid sheets can be made very thin, the radiation-induced explosion is reduced, boosting their stability. These are especially attractive for experiments which benefit from small interaction volumes such as fluctuation X-ray scattering and several types of spectroscopy. Although their use has increased for soft X-ray applications in recent years, there has not yet been wide-scale adoption at XFELs. Here, gas-accelerated liquid sheet jet sample injection is demonstrated at the European XFEL SPB/SFX nano focus beamline. Its performance relative to a conventional liquid jet is evaluated and superior performance across several key factors has been found. This includes a thickness profile ranging from hundreds of nanometres to 60 nm, a fourfold increase in background stability and favorable radiation-induced explosion dynamics at high repetition rates up to 1.13 MHz. Its minute thickness also suggests that ultrafast single-particle solution scattering is a possibility.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2024

Direct Ink Write 3D Printing of Fully Dense and Functionally Graded Liquid Metal Elastomer Foams

Liquid metal (LM) elastomer composites offer promising potential in soft robotics, wearable electronics, and human-machine interfaces. Direct ink write (DIW) 3D printing offers a versatile manufacturing technique capable of precise control over LM microstructures, yet challenges such as interfilament void formation in multilayer structures impact material performance. Here, a DIW strategy is introduced to control both LM microstructure and material architecture. Investigating three key process parameters–nozzle height, extrusion rate, and nondimensionalized nozzle velocity–it is found that nozzle height and velocity predominantly influence filament geometry. The nozzle height primarily dictates the aspect ratio of the filament and the formation of voids. A threshold print height based on filament geometry is identified; below the height, significant surface roughness occurs, and above the ink fractures, which facilitates the creation of porous structures with tunable stiffness and programmable LM microstructure. These porous architectures exhibit reduced density and enhanced thermal conductivity compared to cast samples. When used as a dielectric in a soft capacitive sensor, they display high sensitivity (gauge factor = 9.0), as permittivity increases with compressive strain. These results demonstrate the capability to simultaneously manipulate LM microstructure and geometric architecture in LM elastomer composites through precise control of print parameters, while maintaining geometric fidelity in the printed design.

Spencer Pak↗
DOE OSTI2022

Physical Models from Physical Templates Using Biocompatible Liquid Crystal Elastomers as Morphologically Programmable Inks For 3D Printing

Advanced manufacturing has received considerable attention as a tool for the fabrication of cell scaffolds however, finding ideal biocompatible and biodegradable materials that fit the correct parameters for 3D printing and guide cells to align remain a challenge. Herein, a photocrosslinkable smectic-A (Sm-A) liquid crystal elastomer (LCE) designed for 3D printing is presented, that promotes cell proliferation but most importantly induces cell anisotropy. The LCE-based bio-ink allows the 3D duplication of a highly complex brain structure generated from an animal model. Vascular tissue models are generated from fluorescently stained mouse tissue spatially imaged using confocal microscopy and subsequently processed to create a digital 3D model suitable for printing. The 3D structure is reproduced using a Digital Light Processing (DLP) stereolithography (SLA) desktop 3D printer. Synchrotron Small-Angle X-ray Diffraction (SAXD) data reveal a strong alignment of the LCE layering within the struts of the printed 3D scaffold. The resultant anisotropy of the LCE struts is then shown to direct cell growth. This study offers a simple approach to produce model tissues built within hours that promote cellular alignment.

3D cell culture↗
DOE OSTI2022

Two–Photon Polymerized Shape Memory Microfibers: A New Mechanical Characterization Method in Liquid

Two-photon polymerization (TPP) is widely used to create 3D micro- and nanoscale scaffolds for biological and mechanobiological studies, which often require the mechanical characterization of the TPP fabricated structures. To satisfy physiological requirements, most of the mechanical characterizations need to be conducted in liquid. However, previous characterizations of TPP fabricated structures are all conducted in air due to the limitation of conventional micro- and nanoscale mechanical testing methods. In this study, a new experimental method is reported for testing the mechanical properties of TPP-printed microfibers in liquid. The experiments show that the mechanical behaviors of the microfibers tested in liquid are significantly different from those tested in air. By controlling the TPP writing parameters, the mechanical properties of the microfibers can be tailored over a wide range to meet a variety of mechanobiology applications. In addition, it is found that, in water, the plasticly deformed microfibers can return to their predeformed shape after tensile strain is released. The shape recovery time is dependent on the size of microfibers. The experimental method represents a significant advancement in mechanical testing of TPP fabricated structures and may help release the full potential of TPP fabricated 3D tissue scaffolds for mechanobiological studies.

36 MATERIALS SCIENCE↗
DOE OSTI2022

All‐Printed Ultrahigh‐Responsivity MoS 2 Nanosheet Photodetectors Enabled by Megasonic Exfoliation

Abstract Printed 2D materials, derived from solution‐processed inks, offer scalable and cost‐effective routes to mechanically flexible optoelectronics. With micrometer‐scale control and broad processing latitude, aerosol‐jet printing (AJP) is of particular interest for all‐printed circuits and systems. Here, AJP is utilized to achieve ultrahigh‐responsivity photodetectors consisting of well‐aligned, percolating networks of semiconducting MoS 2 nanosheets and graphene electrodes on flexible polyimide substrates. Ultrathin (≈1.2 nm thick) and high‐aspect‐ratio (≈1 μm lateral size) MoS 2 nanosheets are obtained by electrochemical intercalation followed by megasonic atomization during AJP, which not only aerosolizes the inks but also further exfoliates the nanosheets. The incorporation of the high‐boiling‐point solvent terpineol into the MoS 2 ink is critical for achieving a highly aligned and flat thin‐film morphology following AJP as confirmed by grazing‐incidence wide‐angle X‐ray scattering and atomic force microscopy. Following AJP, curing is achieved with photonic annealing, which yields quasi‐ohmic contacts and photoactive channels with responsivities exceeding 10 3 A W −1 that outperform previously reported all‐printed visible‐light photodetectors by over three orders of magnitude. Megasonic exfoliation coupled with properly designed AJP ink formulations enables the superlative optoelectronic properties of ultrathin MoS 2 nanosheets to be preserved and exploited for the scalable additive manufacturing of mechanically flexible optoelectronics.

2D materials↗
NASA NTRS2010

Serrating Nozzle Surfaces for Complete Transfer of Droplets

A method of ensuring the complete transfer of liquid droplets from nozzles in microfluidic devices to nearby surfaces involves relatively simple geometric modification of the nozzle surfaces. The method is especially applicable to nozzles in print heads and similar devices required to dispense liquid droplets having precise volumes. Examples of such devices include heads for soft printing of ink on paper and heads for depositing droplets of deoxyribonucleic acid (DNA) or protein solutions on glass plates to form microarrays of spots for analysis. The main purpose served by the present method is to ensure that droplets transferred from a nozzle have consistent volume, as needed to ensure accuracy in microarray analysis or consistent appearance of printed text and images. In soft printing, droplets having consistent volume are generated inside a print head, but in the absence of the present method, the consistency is lost in printing because after each printing action (in which a drop is ejected from a nozzle), a small residual volume of liquid remains attached to the nozzle. By providing for complete transfer of droplets (and thus eliminating residual liquid attached to the nozzle) the method ensures consistency of volume of transferred droplets. An additional benefit of elimination of residue is prevention of cross-contamination among different liquids printed through the same nozzle a major consideration in DNA microarray analysis. The method also accelerates the printing process by minimizing the need to clean a printing head to prevent cross-contamination. Soft printing involves a hydrophobic nozzle surface and a hydrophilic print surface. When the two surfaces are brought into proximity such that a droplet in the nozzle makes contact with the print surface, a substantial portion of the droplet becomes transferred to the print surface. Then as the nozzle and the print surface are pulled apart, the droplet is pulled apart and most of the droplet remains on the print surface. The basic principle of the present method is to reduce the liquid-solid surface energy of the nozzle to a level sufficiently below the intrinsic solid-liquid surface energy of the nozzle material so that the droplet is not pulled apart and, instead, the entire droplet volume becomes transferred to the print surface. In this method, the liquid-solid surface energy is reduced by introducing artificial surface roughness in the form of micromachined serrations on the inner nozzle surface (see figure). The method was tested in experiments on soft printing of DNA solutions and of deionized water through 0.5-mm-diameter nozzles, of which some were not serrated, some were partially serrated, and some were fully serrated. In the nozzles without serrations, transfer was incomplete; that is, residual liquids remained in the nozzles after printing. However, in every nozzle in which at least half the inner surface was serrated, complete transfer of droplets to the print surface was achieved.

Kim, Chang-Jin "CJ"↗
DOE OSTI2020

Stabilizing Aqueous Three-Dimensional Printed Constructs Using Chitosan-Cellulose Nanocrystal Assemblies

The assembly and binding of nanoparticles at the interfaces of aqueous two-phase systems enable the three-dimensional (3D) printing of all-aqueous naturally occurring materials. When a dispersion of cellulose nanocrystals (CNCs) in an aqueous solution of polyethylene glycol (PEG) is brought into contact with chitosan dissolved in an aqueous solution of dextran, the CNCs and chitosan diffuse to the interface between the two immiscible aqueous solutions, electrostatically interact, and form a solid, membranous layer sufficiently rapidly to 3D print tubules of one liquid in the other. Additionally, the diameter, length, spatial arrangement, and stability of the printed tubules can be broadly controlled. Adsorption and directional diffusion of ionic species across the membranous layer make heavy metal ion removal possible. The results present a platform for fabricating and developing all-aqueous compartmentalized systems where function can be independently coupled to the inherent functionality of the nanoparticles or ligands.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

High-throughput printing of combinatorial materials from aerosols

The development of new materials and their compositional and microstructural optimization are essential in regard to next-generation technologies such as clean energy and environmental sustainability. However, materials discovery and optimization have been a frustratingly slow process. The Edisonian trial-and-error process is time consuming and resource inefficient, particularly when contrasted with vast materials design spaces 1 . Whereas traditional combinatorial deposition methods can generate material libraries 2,3 , these suffer from limited material options and inability to leverage major breakthroughs in nanomaterial synthesis. Here we report a high-throughput combinatorial printing method capable of fabricating materials with compositional gradients at microscale spatial resolution. In situ mixing and printing in the aerosol phase allows instantaneous tuning of the mixing ratio of a broad range of materials on the fly, which is an important feature unobtainable in conventional multimaterials printing using feedstocks in liquid–liquid or solid–solid phases 4–6 . We demonstrate a variety of high-throughput printing strategies and applications in combinatorial doping, functional grading and chemical reaction, enabling materials exploration of doped chalcogenides and compositionally graded materials with gradient properties. The ability to combine the top-down design freedom of additive manufacturing with bottom-up control over local material compositions promises the development of compositionally complex materials inaccessible via conventional manufacturing approaches.

36 MATERIALS SCIENCE↗
DOE OSTI2020

CHAPTER 9. Bijels the Easy Way

Spinodal decomposition is not the only way to make a bijel. Indeed, while spinodal decomposition produces structures with a potentially useful morphology, it can be challenging to make bijels using this method and the resulting systems can be hard to process and manipulate. Furthermore, exploiting the functional properties of the assembled particle monolayer is extremely challenging. Here, we show how the assembly of nanoparticle surfactants at the liquid–liquid interface can be used to kinetically trap liquids into a wealth of complex structures without using spinodal decomposition. We apply liquid three-dimensional printing and moulding methods, along with patterned substrates with controllable wetting properties, to build all-liquid devices with applications in chemical synthesis, separation, and purification. The functional properties of the assembled nanomaterials can be exploited to produce interfacially structured liquids that are plasmonically and magnetically responsive. Finally, we conclude by arguing that, while the field shows great promise, efforts need to be made to translate liquid bicontinuous systems out of the laboratory and into meaningful, real-world applications, as well applications in more ‘exotic’ disciplines, such as synthetic biology.

36 MATERIALS SCIENCE↗
NASA NTRS2016

Additive Manufacturing for Affordable Rocket Engines

Additive manufacturing (also known as 3D printing) technology has the potential to drastically reduce costs and lead times associated with the development of complex liquid rocket engine systems. NASA is using 3D printing to manufacture rocket engine components including augmented spark igniters, injectors, turbopumps, and valves. NASA is advancing the process to certify these components for flight. Success Story: MSFC has been developing rocket 3D-printing technology using the Selective Laser Melting (SLM) process. Over the last several years, NASA has built and tested several injectors and combustion chambers. Recently, MSFC has 3D printed an augmented spark igniter for potential use the RS-25 engines that will be used on the Space Launch System. The new design is expected to reduce the cost of the igniter by a factor of four. MSFC has also 3D printed and tested a liquid hydrogen turbopump for potential use on an Upper Stage Engine. Additive manufacturing of the turbopump resulted in a 45% part count reduction. To understanding how the 3D printed parts perform and to certify them for flight, MSFC built a breadboard liquid rocket engine using additive manufactured components including injectors, turbomachinery, and valves. The liquid rocket engine was tested seven times in 2016 using liquid oxygen and liquid hydrogen. In addition to exposing the hardware to harsh environments, engineers learned to design for the new manufacturing technique, taking advantage of its capabilities and gaining awareness of its limitations. Benefit: The 3D-printing technology promises reduced cost and schedule for rocket engines. Cost is a function of complexity, and the most complicated features provide the largest opportunities for cost reductions. This is especially true where brazes or welds can be eliminated. The drastic reduction in part count achievable with 3D printing creates a waterfall effect that reduces the number of processes and drawings, decreases the amount of touch labor required, and increases reliability. When certification is achieved, NASA missions will be able to realize these benefits.

West, Brian↗
DOE OSTI2021

System and method for controlling oxidation of metals during freeform casting

A system is disclosed for printing a component. The system may have a nozzle controlled for movement within a plane. The nozzle may be configured to dispense a molten metal. A substrate may be positioned within a reservoir. The substrate may receive the molten metal to form the component in a printing operation. A heated barrier material in a molten state may be contained within the reservoir for forming a liquid barrier between an atmosphere and the substrate. The nozzle has a tip which is submerged within the liquid barrier while dispensing the molten metal during the printing operation. The liquid barrier forms a barrier between an atmosphere in a vicinity of the substrate and the substrate.

Pascall, Andrew J.↗
DOE OSTI2022

Multi-scale characterization of supersolidus liquid phase sintered H13 tool steel manufactured via binder jet additive manufacturing

Additive manufacturing (AM) of H13 tool steel by binder jet 3D printing (BJ3DP) followed by pressureless supersolidus liquid phase sintering (SLPS) provides a low-cost alternative manufacturing method for components with intricate geometric features. However, the microstructure-mechanical property relationships for BJ3DP-SLPS produced H13 tool steel are not well understood, which makes it challenging to develop printing and post-processing methods that maximize part performance. In this work, we leverage atom probe tomography and transmission electron microscopy along with thermodynamic calculations to rationalize the microstructure-mechanical property relationships in as-sintered BJ3DP H13 tool steel. Here, we report for the first time, the presence of a continuous eutectic film-like carbide in H13 along with the more commonly observed cuboidal MX carbides in the prior liquid channels of the microstructure. Further, atom probe tomography revealed the interconnected nature of the MX carbides that appear to be discrete in two-dimensional micrographs. These continuous eutectic carbides and interconnected MX carbides result in brittle failure of the material. Characterization of these microstructural features will be critical in developing appropriate post-processing heat treatments for the improved mechanical performance of BJ3DP H13.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Design and construction of 3D printed devices to investigate active and passive bacterial dispersal on hydrated surfaces

Background: To disperse in water-unsaturated environments, such as the soil, bacteria rely on the availability and structure of water films forming on biotic and abiotic surfaces, and, especially, along fungal mycelia. Dispersal along such “fungal highways” may be driven both by mycelial physical properties and by interactions between bacteria and fungi. However, we still do not have a way to disentangle the biotic and abiotic elements. Results: We designed and 3D printed two devices establishing stable liquid films that support bacteria dispersal in the absence of biotic interactions. The thickness of the liquid film determined the presence of hydraulic flow capable of transporting non-motile cells. In the absence of flow, only motile cells can disperse in the presence of an energy source. Non-motile cells could not disperse autonomously without flow but dispersed as “hitchhikers” when co-inoculated with motile cells. Conclusions: The 3D printed devices can be used as an abiotic control to study bacterial dispersal on hydrated surfaces, such as plant roots and fungal hyphae networks in the soil. By teasing apart the abiotic and biotic dimensions, these 3D printed devices will stimulate further research on microbial dispersal in soil and other water-unsaturated environments.

3D printing↗