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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Parametric Study of Carbon Nanotube Production by Laser Ablation Process

Carbon nanotubes form a new class of nanomaterials that are presumed to have extraordinary mechanical, electrical and thermal properties. The single wall nanotubes (SWNTs) are estimated to be 100 times stronger than steel with 1/6th the weight; electrical carrying capacity better than copper and thermal conductivity better than diamond. Applications of these SWNTs include possible weight reduction of aerospace structures, multifunctional materials, nanosensors and nanoelectronics. Double pulsed laser vaporization process produces SWNTs with the highest percentage of nanotubes in the output material. The normal operating conditions include a green laser pulse closely followed by an infrared laser pulse. Lasers ab late a metal-containing graphite target located in a flow tube maintained in an oven at 1473K with argon flow of 100 sccm at a 500 Torr pressure. In the present work a number of production runs were carried out, changing one operating condition at a time. We have studied the effects of nine parameters, including the sequencing of the laser pulses, pulse separation times, laser energy densities, the type of buffer gas used, oven temperature, operating pressure, flow rate and inner flow tube diameters. All runs were done using the same graphite target. The collected nanotube material was characterized by a variety of analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman and thermo gravimetric analysis (TGA). Results indicate trends that could be used to optimize the process and increase the efficiency of the production process.

Arepalli, Sivaram↗
NASA NTRS2015

NASA Work Experience

I have had the opportunity to support the analytical laboratories in chemical analysis of unknown samples, using Optical Microscopy (OM), Polarizing Light Microscopy (PLM), Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEMEDS), and X-ray Powder Diffraction (XPD). I have assisted in characterizing fibers pulled from a spacecraft, a white fibrous residue discovered in a jet refueler truck, brown residue from a plant habitat slated for delivery to the ISS (International Space Station), corrosion on a pipe from a sprinkler, and air filtration material brought back from the ISS. I also conducted my own fiber study in order to practice techniques and further my understanding of background concepts. Furthermore, I had the opportunity to participate in diverse work assignments, where I was assigned to work with other branches of the engineering department for 1-2 days each. The first was in the Materials Science branch where I participated in the construction of the plant habitat intended for use in research aboard the ISS. The second was in the Testing Design branch where I assisted with tensile and hardness testing of over 40 samples. In addition, I have had the privilege to attend multiple tours of the NASA KSC campus, including to the Astronaut Crew Quarters, the VAB (the main area, the Columbia room, and the catwalk), the Visitor Center housing the shuttle Atlantis, the Saturn-V exhibit, the Prototype laboratory, SWAMP WORKS, the Shuttle Landing Facility, the Crawler, and the Booster Fabrication Facility (BFF). Lastly, much of my coursework prepared me for this experience, including numerous laboratory courses with topics diverse as chemistry, physics, and biology.

Florida Tech↗
NASA NTRS2021

5 Inch Thick 2219-T87 Plate Low Ductility Investigation - Material Analysis on Broken 2219 Tensile Samples

2219-T87 material used on a LOX tank baffle support on Artemis-I showed unusually low fracture elongation. Recent material data indicated 5” thick 2219-T87 plate stock had very low ductility (<1%) in the short transverse direction at the half-thickness location. Metallurgical analysis performed to understand the root cause that led to the drastic reduction in tensile ductility. The PowerPoint report details the key findings from material analysis by optical and scanning electron microscopy.

aluminum alloy 2219↗
DOE OSTI2025

Time at Temperature Abstract and Intern Poster

Current NRC regulations for BWR operations dictate that any occurrence reaching the point of Departure from Nucleate Boiling (DNB) disqualifies the use of the fuel rod for further reactor operation. That criteria does not account for duration of rate of the power increase, the corresponding effects on material properties or rewetting that may occur. Previous Anticipated Operational Occurrences (AOOs) show short durations power increase that may require limited amounts of heat removal. Industrial experience has shown evidence that fuel can reach dryout yet continue to safely operate in regular reactor conditions. The gap in research into such occurrences is the motivation for a series of experiments, including this current work. Time-at-Temperature experiments aim to identify and characterize the microstructural changes in Zircaloy-2 under oxygen-free high temperatures. This work uses the FlashDSC instrument to rapidly ramp up and down the temperature of a focus ion beam (FIB) prepared large area lift-out (LALO) of Zircaloy-2 at a rate of 10,000 K/s to desired values. The focus is to characterize the microstructure evolution, if any, of Zircaloy-2 that may impact its performance under typical BWR conditions. This characterization includes analyzing grain structure and size, secondary phase particle (SPPs) size, shape, composition, and location using Transmission Electron Microscopy (TEM). Further data collection and analysis is in progress including diffraction pattern indexing and 4D STEM processing. While current results focus on the testing and characterizing unirradiated material, future plans include expansion to irradiated material to explore the effects of rapid transition rates seen in DNB and dryout conditions on irradiationg damage and defect annealing.

36 - MATERIALS SCIENCE↗
NASA NTRS1985

Analysis of normal and transparent silver Teflon

Samples of Inconel/silver/Teflon exposed to solar radiation, and atomic oxygen on Solar Max were microcharacterized. Those samples exposed to atomic oxygen from the metallic side had become transparent while those exposed from the Teflon side remained reflective. The difference between the transparent and non-transparent material was determined. Microcharacterization of these Inconel/silver/Teflon samples was performed using scanning electron microscopy with windowless energy dispersive X ray analysis, secondary ion mass spectrometry, and X ray photoelectron spectroscopy.

Stuckey, W. K.↗
NASA NTRS1984

High speed quantitative digital microscopy

Modern digital image processing hardware makes possible quantitative analysis of microscope images at high speed. This paper describes an application to automatic screening for cervical cancer. The system uses twelve MC6809 microprocessors arranged in a pipeline multiprocessor configuration. Each processor executes one part of the algorithm on each cell image as it passes through the pipeline. Each processor communicates with its upstream and downstream neighbors via shared two-port memory. Thus no time is devoted to input-output operations as such. This configuration is expected to be at least ten times faster than previous systems.

Castleman, K. R.↗
DOE OSTI2025

Phase segregation dynamics in mixed-halide perovskites revealed by plunge-freeze cryo-electron microscopy

Mixed-halide lead perovskites, with photoexcited charge-carrier properties suitable for high-efficiency photovoltaics, hold significant promise for high-efficiency tandem solar cells. However, phase segregation under illumination, where an iodide-rich phase forms carrier trap states, remains a barrier to application. This study employs plunge-freeze cryoelectron microscopy to visualize nanoscale phase segregation dynamics in CsPb(Br x I 1–x ) 3 films. By rapidly freezing the illuminated samples, we preserve transient photoexcited ion distributions for high-resolution structural and compositional analysis at the nanoscale. Cryogenic scanning transmission electron microscopy (STEM) techniques (electron energy loss spectroscopy [EELS] and 4D-STEM) captured the dynamics of photo-induced iodine migration from grain boundaries to centers, identified the buildup of anisotropic strain, and captured the heterogeneous evolution of this process within a single grain. These findings provide insight into microscopic phase segregation mechanisms and their dynamics, enhancing our understanding of mixed-halide perovskite photostability.

42 ENGINEERING↗
NASA NTRS1995

Modification of Experimental Protocols for a Space Shuttle Flight and Applications for the Analysis of Cytoskeletal Structures During Fertilization, Cell Division , and Development in Sea Urchin Embryos

To explore the role of microgravity on cytoskeletal organization and skeletal calcium deposition during fertilization, cell division, and early development, the sea urchin was chosen as a model developmental system. Methods were developed to employ light, immunofluorescence, and electron microscopy on cultures being prepared for flight on the Space Shuttle. For analysis of microfilaments, microtubules, centrosomes, and calcium-requiring events, our standard laboratory protocols had to be modified substantially for experimentation on the Space Shuttle. All manipulations were carried out in a closed culture chamber containing 35 ml artificial sea water as a culture fluid. Unfertilized eggs stored for 24 hours in these chambers were fertilized with sperm diluted in sea water and fixed with concentrated fixatives for final fixation in formaldehyde, taxol, EGTA, and MgCl2(exp -6)H2O for 1 cell to 16 cell stages to preserve cytoskeletal structures for simultaneous analysis with light, immunofluorescence, and electron microscopy, and 1.5 percent glutaraldehyde and 0.4 percent formaldehyde for blastula and plueus stages. The fixed samples wre maintained in chambers without degradation for up to two weeks after which the specimens were processed and analyzed with routine methods. Since complex manipulations are not possible in the closed chambers, the fertilization coat was removed from fixation using 0.5 percent freshly prepared sodium thioglycolate solution at pH 10.0 which provided reliable immunofluorescence staining for microtubules. Sperm/egg fusion, mitosis, cytokinesis, and calcium deposition during spicule formatin in early embryogenesis were found to be without artificial alterations when compared to cells fixed fresh and processed with conventional methods.

Chakrabarti, Amitabha↗
NASA NTRS1972

Particle impact and optical property analysis of the surfaces of Surveyor 3 materials

As part of the investigation of Surveyor 3 materials, a study was conducted to determine the effect of the lunar environment on some of the painted and unpainted exterior surfaces. Examination of the camera parts and tube sections was conducted using three techniques: (1) optical and scanning electron microscopy, (2) energy dispersive X-ray probe analysis, and (3) spectral reflectance measurements.

Anderson, D. L.↗
NASA NTRS2017

Small Particle Impact Damage on Different Glass Substrates

Impact experiments using sand particles were performed on four distinct glass substrates. The sand particles were characterized using the X-Ray micro-CT technique; 3-D reconstruction of the particles was followed by further size and shape analyses. High-speed video footage from impact tests was used to calculate the incoming and rebound velocities of the individual sand impact events, as well as particle volume. Further, video analysis was used in conjunction with optical and scanning electron microscopy to relate the incoming velocity and shape of the particles to subsequent fractures, including both radial and lateral cracks. Analysis was performed using peridynamic simulations.

Waxman, R.↗
NASA NTRS2023

The Spatial Distribution of Soluble Organic Matter and Their Relationship to Minerals in the Asteroid (162173) Ryugu

We performed in-situ analysis on a ~1 mm-sized grain A0080 returned by the Hayabusa2 spacecraft from near-Earth asteroid (162173) Ryugu to investigate the relationship of soluble organic matter (SOM) to minerals. Desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) imaging mapped more than 200 CHN, CHO, CHO–Na (sodium adducted), and CHNO soluble organic compounds. A heterogeneous spatial distribution was observed for different compound classes of SOM as well as among alkylated homologues on the sample surface. The A0080 sample showed mineralogy more like an Ivuna-type (CI) carbonaceous chondrite than other meteorites. It contained two different lithologies, which are either rich (lithology 1) or poor (lithology 2) in magnetite, pyrrhotite, and dolomite. CHN compounds were more concentrated in lithology 1 than in lithology 2; on the other hand, CHO, CHO–Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is likely the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. Organic-related ions measured by time-of-flight secondary ion mass spectrometry (ToF–SIMS) did not coincide with the spatial distribution revealed by DESI-HRMS imaging. This result may be because the different ionization mechanism between DESI and SIMS, or indicate that the ToF–SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. In the Orgueil meteorite, such relationship between altered minerals and SOM distributions was not observed by DESI-HRMS analysis and field-emission scanning electron microscopy, which would result from differences of SOM formation processes and sequent alteration process on the parent bodies or even on the Earth. Alkylated homologues of CHN compounds were identified in A0080 by DESI-HRMS imaging as observed in the Murchison meteorite, but not from the Orgueil meteorite. These compounds with a large C number were enriched in Murchison fragments with abundant carbonate grains. In contrast, such relationship was not observed in A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on the Murchison parent body and asteroid Ryugu.

Ryugu↗
DOE OSTI2025

Spatially Resolved Raman Spectroscopy of Thin Carbon Interphase in SiC Ceramic Matrix Composites

A dedicated analysis method is presented to extract the Raman spectrum of an interphase layer thinner than the laser spot size. We focused on spatial correlations between the contrast of optical micrographs and Raman hyperspectral data to predict the constituents of the mixed spectra measured near the interphase. By employing a mapping step size of 0.1 μm, the Raman spectrum of approximately 0.3-μm-thick carbon interphase in a SiC fiber-reinforced SiC matrix composite was extracted from data acquired with a theoretical spot size of about 0.7 μm. Notably, conventional chemometrics procedures were unable to isolate the interphase signal, instead producing a spectrum representing a mixture of interphase and matrix. This study used another composite with approximately 0.9-μm-thick interphase to validate the analysis method, enabling direct measurement of the interphase spectrum. The proposed Raman analysis method has advantages in specimen volume and turnaround time compared to traditional characterization methods, such as transmission electron microscopy. In conclusion, this study also evaluates the applicability of the analysis method to different composite materials and identifies key requirements of the measurements, including the ratio of interphase thickness to spot size and the homogeneity of the surrounding matrix.

ceramic matrix composite↗
DOE OSTI2024

Evidence of Directional Structural Superlubricity and Lévy Flights in a van der Waals Heterostructure

Abstract Structural superlubricity is a special frictionless contact in which two crystals are in incommensurate arrangement such that relative in‐plane translation is associated with vanishing energy barrier crossing. So far, it has been realized in multilayer graphene and other van der Waals (2D crystals with hexagonal or triangular crystalline symmetries, leading to isotropic frictionless contacts. Directional structural superlubricity, to date unrealized in 2D systems, is possible when the reciprocal lattices of the two crystals coincide in one direction only. Here, directional structural superlubricity a α‐bismuthene/graphite van der Waals system is evidenced, manifested by spontaneous hopping of the islands over hundreds of nanometers at room temperature, resolved by low‐energy electron microscopy and supported by registry simulations. Statistical analysis of individual and collective α‐bismuthene islands populations reveal a heavy‐tailed distribution of the hopping lengths and sticking times indicative of Lévy flight dynamics, largely unobserved in condensed‐matter systems.

Le Ster, Maxime↗
DOE OSTI2025

Unsupported and carbon-supported silver catalysts for oxygen reduction reaction in alkaline media

Quick and easy Ag catalysts preparation via wet chemical synthesis method using only reducing agent (pure-Ag); reducing agent and citric acid as the capping agent (Ag-CA); and carbon support (KetjenBlack 600J), capping agent, and the reducing agent (Ag/C) is demonstrated. The Ag-based electrocatalysts are characterized by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) with energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of Ag catalysts for O 2 reduction reaction (ORR) in 1 M KOH is evaluated using the rotating (ring)-disc electrode method. SEM and HAADF-STEM results show that the unsupported pure-Ag and Ag-CA catalysts consist mainly of big agglomerates, and Ag/C has the smallest agglomerates and some sub-3 nm Ag nanoparticles. The XPS results reveal that Ag in all the catalysts is in the metallic form (Ag 0 ). Despite consisting of big agglomerates, the Ag-CA catalyst exhibits similar ORR electrocatalytic activity to that of Ag/C. Ag-CA (unsupported) shows the lowest hydrogen peroxide yield. These results are of great importance for the development of Ag-based catalysts that can be prepared in a fast, simple and easily up scalable fashion, for anion exchange membrane fuel cells.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Parameter development and characterization of laser powder directed energy deposition of Nb – Alloy C103 for thin wall geometries

This work focuses on the parameter development and microstructural characterization of Nb-based alloy C103 for thin wall structures produced via laser powder – directed energy deposition (LP – DED). Laser power and scanning speeds were varied as part of a design of experiments to identify adequate print parameters. Combinations were evaluated for relative density, porosity, and geometrical accuracy. A combination of a laser power of 1420 W and scanning speed of 14 mm/s resulted in a relative density >99%, exhibited a consistent weld bead profile and was used for further microstructural evaluation. A mix of optical and scanning electron microscopy (SEM) revealed small, slightly elongated grains along the edges and large epitaxial grains in the central region along the Build – Transverse view. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis revealed Hf rich columnar cells in the center that transition into an evenly spaced cellular structure towards the edges of the built sample. Electron backscatter diffraction (EBSD) scans show a sharp [001] texture when looking at the cross section of the sample along the build direction. The Build – Scan view revealed a zig – zag pattern that follows the back – and – forth deposition strategy that was used. Finally, microhardness measurements were taken in the as – built (AB) and stress relieved (SR) conditions to baseline preliminary mechanical properties. The AB condition exhibited a large amount of scatter in the data and averages up to 11% larger than the SR condition. The reduction in scatter upon applying the SR cycle are indicative of a large concertation of dislocations present in the AB condition.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Evaluation of corrosion coupons exposed to molten-chloride electrorefiner salts long term

Corrosion mitigation has long been considered a challenge in long-term service of both pyrochemical reprocessing and molten salt reactor applications. Corrosion coupons consisting of 2.25Cr 1Mo ASME SA387 Grade 22 Class 2 steel, were installed in a uranium electrorefiner containing molten chloride salt at 500°C. This electrorefiner went into service at Idaho National Laboratory in 1994. Seven of these coupons were removed in 2019 (i.e., submerged in molten salt for 25 years) for analysis and characterization including neutron imaging, optical microscopy, scanning electron microscopy, and wave/energy dispersive x-ray spectroscopy. The results showed that all seven coupons experienced between 30 to 175 µm of surface degradation without evidence of brittle fracture. Meaning there was no evidence of accelerated corrosion or fractures, and the average steel surface loss was of less than 5 µm per year. All indications were that the environmental conditions inside the electrorefiner were favorable for the steel alloy.

36 - MATERIALS SCIENCE↗
DOE OSTI2024

High-Temperature Ferrofluids Based on Molten Salts

Molten metal chloride salts are promising candidates for advanced heat transfer fluids in generation IV nuclear reactors and beyond. However, research on the magnetic properties of suspended metallic nanoparticles at elevated temperatures is scarce, and there have been no attempts to develop a high-temperature, molten salt based ferrofluid. Such a ferrofluid would enable in situ manipulation of both the physical and thermal properties of the fluid via an external magnetic field. This study examines molten salt based ferrofluids comprised of metallic cobalt nanoparticles dispersed in molten metal chloride salts. High-temperature magnetometry and magneto-thermogalvometric measurements were conducted to evaluate the magnetic characteristics of the ferrofluid. Further analysis was conducted through a combination of microscopy, spectroscopy, solubility tests, and diffraction measurements. Furthermore, the metallic cobalt nanoparticles exhibited a notable degree of chemical stability and sustained magnetism from 25 to 800 °C when suspended in NaCl–MgCl 2 and KCl–ZnCl 2 mixtures.

Cobalt↗
DOE OSTI2025

Uptake and binding of La 3+ and Cr 3+ ions by alkali metal substituted alpha-zirconium phosphate

The conversion of alpha-zirconium phosphate, Zr(HPO 4 ) 2 ·H 2 O, to the K-, Rb-, and Cs-phases and the subsequent ion exchange behavior of these alkali metal phases, A-ZrP, with La 3+ and Cr 3+ have been investigated. The conversion to the A-ZrP phases was achieved by reaction with metal chloride, metal hydroxide solution, and confirmed through various techniques, including X-ray powder diffraction, thermogravimetry analysis, IR spectroscopy, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. The effect of material hydration, which increased the interlayer distance, was also examined. The ion exchange behavior of the A-ZrP showed strong affinity for both La 3+ , a representative for trivalent lanthanide metals, and Cr 3+ , a representative for the trivalent transition metals, with a rapid, near quantitative removal of the M 3+ ions at a pH of 3 when the ion concentration was ≤25% of the ion exchange capacity of the materials. Additionally, the ion affinity was shown to be pH and concentration-dependent, decreasing with a decrease in pH or an increase in ion concentration. Lastly, the binding strength of La- and Cr-loaded ZrP materials was examined through a series of leaching experiments in a carbonate buffer, phosphate buffer, HEPES buffer, and a series of EDTA solutions at various concentrations. No observable leaching occurred in the carbonate buffer, phosphate buffer, HEPES buffer, or when the EDTA concentration was below 0.1 mM. These results highlight the potential for the A-ZrP materials to provide a platform for trivalent transition metal and trivalent lanthanide radionuclide capture for various applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗