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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

ELASTOMERIC MICROVASCULAR SELF-HEALING MATERIALS

Damaged elastomeric diaphragms within pneumatic controllers used in the oil and gas industry lead to an unintended release of methane. Self-healing microvascular materials capable of healing various types of damage have been fabricated. These microvascular materials are designed to replace currently available commercial diaphragms found in pneumatic controllers and provide a solution to reduce unintended methane leaks. Poly(dimethylsiloxane) (PDMS) was used as the main matrix material, with additional testing conducted on polyurethane and flexibilised epoxy materials. Microvascular networks were implemented into the elastomeric membranes to act as ves- sels to deliver healing agents to the damaged areas. The complex, interdigitated channel networks were created using a 3D printed custom compounded filament composed of polylactic acid (PLA) and tin(II) oxalate. Two-part liquid casting polymers were poured around the channels into a mould to create samples with the scaffolding of the microvascular channels intact. Hollow microvascular networks were created by placing the samples within a vacuum oven at 250◦C which causes the thermal depolymerisation of PLA into its gaseous monomers. The manufactured materials were placed in test stands and pressurized using nitrogen gas to determine their healing and mechanical behaviour. Self-healing behaviour was demonstrated using PDMS matrix materials and healing chemistries within a pressure test cell. This test cell was designed to detect any damage to a sample by record- ing an outlet pressure. Damages including puncture holes, diagonal cuts and star-shaped central iv cuts were applied to the samples and a reduction in the outlet pressure was recorded for all sam- ples. A variation in channel spacing and diameter was studied to determine the optimal design of the microvascular network for self-healing performance. The mechanical performance of elastomeric membrane materials within a diaphragmatic pressurised stand was observed. Deformations and strains around the channels and channel inter- sections at the midplane of the materials were recorded using digital image correlation. Normal stresses were calculated using Hooke’s law and the material properties of the PDMS matrix. A reduction in leak rate, implying the success of self-healing, was recorded within manu- factured diaphragm samples tested within a commercial valve. PDMS is the favourable material when compared to polyurethane and flexibilised epoxy for creating

03 NATURAL GAS↗
DOE OSTI2021

Visualizing Interfacial Jamming Using an Aggregation-Induced-Emission Molecular Reporter

With the interfacial jamming of nanoparticles (NPs), a load-bearing network of NPs forms as the areal density of NPs increases, converting the assembly from a liquid-like into a solid-like assembly. Unlike vitrification, the lineal packing of the NPs in the network is denser, while the remaining NPs can remain in a liquid-like state. It is a challenge to determine the point at which the assemblies jam, since both jamming and vitrification lead to a solid-like behavior of the assemblies. Herein, we show a real-time fluorescence imaging method to probe the evolution of the interfacial dynamics of NP surfactants at the water/oil interface using aggregation-induced emission (AIE) as a reporter for the transition of the assemblies into the jammed state. The AIEgens show typical fluorescence behavior at densities at which they can move and rotate. However, when aggregation of these fluorophores occurs, the smaller intermolecular separation distance arrests rotation, and a significant enhancement in the fluorescence intensity occurs.

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

Modular, disposable 3D printed microfluidic membrane system for separation and purification

The present disclosure relates to a membrane extraction apparatus for extracting a component from a first liquid. The apparatus may incorporate a housing comprised of first and second mating housing halves, with each housing half having an open faced channel formed therein such that the channels at least partially overlay one another when the two housing halves are secured together. A membrane filter is disposed between the two housing halves to overlay the open faced channels. The membrane filter extracts the component from the first liquid and transfers the component into the second liquid as the first and second liquids flow through the first and second housing halves.

Servis, Anna G.↗
DOE OSTI2021

Transport Modeling of Kinetically Limited Microscale Extraction Systems: Droplet and Supported Liquid Membrane Separations

Microfluidic droplet extraction devices can be used to efficiently measure solute phase transfer kinetics in liquid–liquid extraction systems. In this work, a droplet extraction apparatus was constructed using off-the-shelf and custom 3D printed parts for less than 110 USD. The interfacial kinetics of the transfer of Pu(IV) between an aqueous nitric acid phase and a 5 v/v% tridodecylamine (TDA) in toluene phase were characterized by determining the extent of Pu(IV) transfer between phases at different flow rates. Forward interfacial rate constants calculated from this data using an analytical model are 5.6 × 10 –3 mm s –1 under extraction (aqueous-to-organic solute transfer) conditions and 3.3 × 10 –3 mm s –1 under stripping (organic-to-aqueous solute transfer) conditions. The analytical model is valid when the rate of solute transfer across the interface between the two liquid phases has pseudo-first-order reversible reaction kinetics and is slow relative to the rate of solute transport to the interface. The change in the outlet concentration with residence time determined using the analytical model was compared with the results of a numerical model accounting for advection/diffusion to the interface in addition to kinetically limited interfacial solute transfer. These calculations revealed that for systems with forward interfacial rate constants greater than approximately 10 –2 mm s –1 , the analytical model must be supplemented with a numerical transport model accounting for an additional advection/diffusion mass transfer resistance. This threshold corresponds to a Damköhler number of one. The measured interfacial kinetic rate constants for Pu(IV)/TDA were used in a supported liquid membrane (SLM) numerical model, which showed that the Pu(IV) phase transfer kinetics are fast enough for use in a practical separation.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Modelling the complex evaporated gas flow and its impact on particle spattering during laser powder bed fusion

The additive manufacturing (AM) of metals is becoming an increasingly important production process with the potential to replace traditional techniques such as casting. Laser Powder Bed Fusion (LPBF) is used in many applications to print metal parts from powder. The metal powder is heated locally with sufficient laser radiation that the liquid melt easily reaches its boiling temperature, which leads to a metallic vapour jet that can entrain both powder bed particles and molten droplets. The small size of laser-matter interaction site makes a detailed experimental analysis of the process challenging. Synchrotron X-ray imaging experiments are one of the few methods which can capture the dynamic melting and solidification processes. Comparing such experiments with computer simulations of the process is an important approach in order to better understand the manufacturing process and to analyse the influence of process parameters on the evaporated gas jet and the subsequent impact on particle ejection, leading to potentially reduced AM component quality. The melting and solidification of the metal powder is simulated using an Eulerian multiphase approach based on a control volume discretization of powder bed and substrate and a volume of liquid separation from melt and gas phase. The gas phase modelled as an ideal gas reaches velocities up to 100 m/s. Lagrangian particle tracking in the simulation demonstrates that the velocity fields calculated by the Eulerian multi-phase approach in combination with a standard drag-force model lead to particle accelerations in good agreement with those measured experimentally. In order to avoid numerical laborious Lagrangian calculations, a direct method to compare an Eulerian multiphase simulation with synchrotron X-ray experiments was introduced and validated. This approach is used to analyse the influence of process parameters including laser power and laser speed on the maximal acceleration of particles from the melt pool area. While the particle acceleration increases linearly with line energy in the conduction mode, a linear decrease of the acceleration with increasing line energy can be found in the transition mode before the accel-eration increases again with line energy in the keyhole mode.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Inkless, dry printing nanographene via in-Situ Coordinated laser ablation and sintering processes

Printing carbon, such as graphene and other carbon structures, for flexible and printed electronics currently relies on either ink-based printing, laser-induced forward transfer (LIFT), or laser-induced graphitization (LIG) to convert carbon-rich precursor materials, such as polymers, to graphene-like carbon structures. Liquid inks contain toxic solvents, surfactants, and stabilizing additives that degrade electrical conductivity and require high-temperature post-processing. On the other hand, LIG is limited by the substrate. Here, this study introduces an additive manufacturing method for dry-printing carbon nanomaterials, ranging from amorphous carbon to crystalline graphene-like structures, on various substrates. The system utilizes laser ablation of a solid graphite target to create pure carbon nanoparticles in situ and on demand. An inert gas carries the nanoparticles onto the substrate, where they can be deposited either as amorphous structures or laser-sintered in real time to form various graphitic structures. The study of laser processing parameters, specifically fluence and pulse repetition frequency, revealed three unique regimes of nanostructure evolution that influence the morphological and electrical properties of these printed structures. Raman spectroscopy confirmed graphitization with a resistivity slightly higher than that of the bulk graphite target. The conductivity/resistivity could be tuned as a function of sintering laser power. Scanning transmission electron microscopy (STEM) revealed that turbostratic nanographene formed with an interlayer spacing of 0.40 nm. Despite ink-based printing methods, such as screen printing, inkjet printing (IJP), and aerosol jet printing (AJP), this eco-friendly and green manufacturing technique could eliminate toxic chemicals, reduce environmental impact, and enable single-step fabrication of carbon-based devices for applications in wearable sensors, energy storage, flexible electronics, and Internet of Things (IoT) devices.

Additive nanomanufacturing↗
DOE OSTI2023

Combining direct ink writing with reactive melt infiltration to create architectured thermoelectric legs

Here, we present a new additive-reactive synthesis method where inks – cast into molds or 3D-additively extruded into architectured shapes – are reacted into intermetallic thermoelectric compounds. The new method, as demonstrated for equiatomic TiNiSn, combines: (i) extrusion printing (or casting) of inks containing Ni and Ti powders, (ii) debinding and reactive sintering to form a porous NiTi network, (iii) network infiltration with liquid Sn and subsequent reaction to synthesize the TiNiSn phase. Thin plates, created through this method, show high phase purity and low residual porosity. A thermoelectric figure of merit zT = 0.47 ± 0.05 is achieved at 800 K, within the broad range of values (zT= 0.3–1.0) reported for TiNiSn created via traditional powder hot-pressing methods. Layered TiNiSn microlattices – after 3D ink-extrusion printing and infiltration – exhibit high relative densities and minimal undesirable secondary phase content, with a Seebeck coefficient on par with the ink-cast TiNiSn plates, demonstrating that thermoelectric legs with far-ranging architectural freedom can be created additively with this novel reactive manufacturing method. Numerous other thermoelectric (and other) compounds, currently limited to basic geometries due to brittleness, are amenable to this new method based on a sequence of reactive sintering/infiltration of cast or ink-extruded precursors.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fluid Mechanics Challenges in Direct-Ink-Writing Additive Manufacturing

Direct-ink writing (DIW) has rapidly become a versatile 3D fabrication method due to its ability to deposit a wide range of complex fluids into customizable 3D geometries. This review highlights key fundamental fluid mechanics and soft matter challenges across the different stages of the DIW printing process. The rheology of fluids and suspensions governs the flow behavior through narrow nozzles, posing questions about extrudability, confined flow dynamics, and clogging mechanisms. Downstream, the formation and deposition of extruded filaments involve extensional flows and potential instabilities, while postdeposition dynamics introduces complexities related to yield stress and structural stability. These stages are inherently interdependent, as optimizing material composition without considering filament stability risks compromising the final structure. As DIW applications expand through advanced ink formulations, developing fundamental fluid mechanics frameworks is essential to replace trial-and-error approaches with predictive design methodologies to enable more precise control and improved reliability of the printing process.

3D printing↗
DOE OSTI2026

Tethered Balloon System (TBS) Instrument Handbook

The Tethered Balloon System (TBS) is an unmanned aerial system composed of a helium-filled balloon, tether, winch, and sensors. Individual components of the system may change with each flight based on the desired measurements, atmospheric conditions, and flight strategy. The TBS operates within the U.S. Department of Energy (DOE)’s R-2204 Restricted Airspace, which encompasses a two-nautical-mile radius centered on Oliktok Point, Alaska that is segmented by altitude into R-2204 Low (0-1,499’ MSL or 0-457 m MSL) and R-2204 High (1,500-6,999’ MSL or 457-2133 m MSL). The TBS may operate outside of R-2204 if allowed to do so under a Certificate of Authorization from the Federal Aviation Administration.

42 ENGINEERING↗
DOE OSTI2025

High‐Speed Embedded Ink Writing of Anatomic‐Size Organ Constructs

Embedded ink writing (EIW) is an emerging 3D printing technique that fabricates complex 3D structures from various biomaterial inks but is limited to a printing speed of ∼10 mm s −1 due to suboptimal rheological properties of particulate-dominated yield-stress fluids when used as liquid baths. In this work, a particle-hydrogel interactive system to design advanced baths with enhanced yield stress and extended thixotropic response time for realizing high-speed EIW is developed. In this system, the interactions between particle additive and three representative polymeric hydrogels enable the resulting nanocomposites to demonstrate different rheological behaviors. Accordingly, the interaction models for the nanocomposites are established, which are subsequently validated by macroscale rheological measurements and advanced microstructure characterization techniques. Filament formation mechanisms in the particle-hydrogel interactive baths are comprehensively investigated at high printing speeds. To demonstrate the effectiveness of the proposed high-speed EIW method, an anatomic-size human kidney construct is successfully printed at 110 mm s −1 , which only takes ∼4 h. This work breaks the printing speed barrier in current EIW and propels the maximum printing speed by at least 10 times, providing an efficient and promising solution for organ reconstruction in the future.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Fused filament fabrication of novel phase-change material functional composites

Additively manufactured polymer heat exchangers are of recent interest in the thermal sciences due to their lightweight and intricate heat-transfer-enhancing geometrical features. The goal of the present research is to directly encapsulate phase-change material (PCM) into polymer filament for the purpose of 3D printing polymer heat exchangers capable of latent heat thermal energy storage and management. PCMs have the ability to absorb large amounts of latent heat while undergoing a solid-to-liquid phase change at a nearly constant temperature. Encapsulation or containment of PCMs is necessary to prevent leaking since the material continuously cycles between a liquid and a solid state. An organic-based PCM and high-density polyethylene (HDPE) were combined and extruded into a functional composite filament. For the first time, with the aid of a heated enclosure and HDPE build plates, it was demonstrated that these functional composite materials can be printed using fused filament fabrication (FFF). Printing HDPE is known to be difficult; however, based on what was observed in the current study, the PCM and HDPE composite was easier to print than pure HDPE. Thermal properties, such as latent heat of fusion, phase-change temperature, and thermal conductivity, of the composite filament and 3D printed samples were investigated and compared with compression-molded bulk material. Finally, the microstructures of the composite filament and 3D printed samples were visualized, and the basic structures of the HDPE and PCM within both the filament and 3D printed parts were clearly delineated.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Testing of spark plasma sintered porous tungsten under neon glow discharge cleaning conditions in LTX-β

This paper demonstrates that tungsten (W) based powder reconstituted Plasma Facing Components (PFCs) can be treated in situ in a fusion reactor to remove W oxide and carbon (C) contamination. Doing so should ease the challenge of using these materials in a Capillary Porous System (CPS) with lithium (Li) by enabling better wetting and less contamination of the Li by the underlying CPS. Most powder reconstituted materials including 3D printed and sintered PFCs suffer from a high surface contamination from oxides and surface C, which complicates their use with liquid Li, a primary PFC candidate. Spark plasma sintered porous W samples were fabricated to be used as a CPS with liquid Li. The samples were characterized in terms of morphology and surface chemistry. Analysis confirms a high C and oxygen (O) contamination. We present the results of exposing this type of CPS to Glow Discharge Cleaning (GDC) cycles in the Lithium Tokamak Experiment-β (LTX-β). The sample was exposed to neon (Ne) GDC in the midplane of the low-field side of LTX-β and analyzed in vacuo with Temperature Programmed Desorption (TPD) and Secondary Ion Mass Spectrometry (SIMS) to investigate the effects the Ne GDC had on the chemical composition of the sample. The combination of Ne GDC with rapid heating as done in TPD was successful in reducing the W oxides and removing the C contamination.

Capillary porous system↗
DOE OSTI2025

Production, quality assurance and quality control of the SiPM Tiles for the DarkSide-20k Time Projection Chamber

The DarkSide-20k dark matter direct detection experiment will employ a 21 m 2 silicon photomultiplier (SiPM) array, instrumenting a dual-phase 50 tonnes liquid argon Time Projection Chamber (TPC). SiPMs are arranged into modular photosensors called Tiles, each integrating 24 SiPMs onto a printed circuit board (PCB) that provides signal amplification, power distribution, and a single-ended output for simplified readout. Tiles are further grouped into Photo-Detector Units (PDUs). This paper details the production of the Tiles and the Quality Assurance and Quality Control (QA-QC) protocol established to ensure their performance and uniformity. The production and QA-QC of the Tiles are carried out at Nuova Officina Assergi (NOA), an ISO-6 clean room facility at LNGS. This process includes wafer-level cryogenic characterisation, precision die attaching, wire bonding, and extensive electrical and optical validation of each Tile. The overall production yield exceeds 83.5%, matching the requirements of the DarkSide-20k production plan. These results validate the robustness of the Tile design and its suitability for operation in a cryogenic environment.

Acerbi, F. [Fondazione Bruno Kessler]↗
DOE OSTI2025

Plastic Additive, Sorbent-Coated, Thermally Integrated Contactor for CO 2 Capture (PLASTIC4CO2) (Final Report)

Final report for Plastic Additive, Sorbent-Coated, Thermally Integrated Contactor for CO2 Capture (PLASTIC4CO2) DE-FE-0032132. The goal of the work was to investigate at a technology readiness level of 3 (TRL 3), the proof of concept of an additively printed plastic 2-channel heat exchanger/sorbent contactor system to achieve a 15% lower levelized cost of electricity (LCOE) than a baseline liquid phase amine adsorber system for 90% and 95% capture of CO 2 from both a 7F02 2x1CC and 7HA02 2x1CC natural gas turbines.

03 NATURAL GAS↗
DOE OSTI2024

Silicone Resins for Vat Polymerization Printing

This paper reviews research of silicone-based resins for vat polymerization printing (VPP). Silicone resins are used commonly in other 3D printing technologies because of their desirable properties. Silicones are chemically inert, oxidatively, and thermally stable, and have the lowest glass transition temperature of any polymer. Creating silicone resins processable by VPP is challenging because VPP requires low viscosity liquid resin that quickly photopolymerizes. This review will summarize VPP technologies, resin chemistries, and recent research of silicone VPP resins.

36 MATERIALS SCIENCE↗
DOE OSTI2020

HPC4Mfg with Carbon Inc.

Continuous Liquid Interface Production (CLIP) is poised to bring additive manufacturing to multiple American manufacturing sectors owing to its unique combination of rapid print speeds and material options that resemble injection molding thermoplastics. In spite of these benefits, CLIP is still a maturing process. To improve our understanding and control of the process, this project developed a multi-physics computational model that encompasses the coupled chemical-physical processes of photopolymerization and fluid flow to predict part outcomes. A physically predictive model can enable rapid optimization of CLIP and reduce the current cycle time and waste associated with optimization by four-fold. Ultimately, this effort will help open the U.S. $400B plastic manufacturing industry to the key benefits of additive manufacturing, namely mass customization, unlimited design space, and a cost- and energy-effective path to mainstream manufacturing. In the course of the project we produced a model which coupled fluid-flow, species transport, and photochemistry to model the Carbon CLIP process. As the development proceeded, we validated the code against theory and experiments. The resulting code was transferred to Carbon, and we expect it to be a useful part of their modeling capability. Future work includes improvements to the fluid solver’s robustness and performance, along with the addition of additional physics models.

42 ENGINEERING↗