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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Zinc Removal from Basic Oxygen Steelmaking Filter Cake by Leaching with Organic Acids

The dust generated from the basic oxygen steelmaking (BOS) process is a waste material mainly containing iron that cannot be recycled owing to its high zinc content. In this study, the leaching effects of different organic acids are compared, with the aim of determining an acid that selectively leaches and removes zinc from BOS dust, so that the waste material can be recycled into ironmaking and steelmaking processes in order to substitute part of the raw materials of steelmaking. The dust used in this study was scrubbed and collected in the form of a filter cake. The acids tested were oxalic, citric, acetic, propionic, butyric, and valeric acids. Butyric acid was found to be the most effective, with a high zinc extraction level of 49.7 pct and a low iron level of only 2.5 pct. Oxalic acid was the least effective leaching reagent for both zinc and iron extractions, owing to the formation of zinc and iron oxalate precipitates following metal dissolution. The filter cake and leached residues were characterized by chemical analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy with energy dispersive spectroscpopy.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Performance of a size-selected nanocluster deposition facility and in situ characterization of grown films by x-ray photoelectron spectroscopy

We report here on a newly installed gas aggregation type nanocluster deposition unit based on magnetron sputtering ion source with mass selection of the clusters by quadrupole mass filter. The system is ultra high vacuum compatible and is equipped with an in situ X-ray Photoelectron Spectroscopy facility, giving compositional information of the films formed by nanoclusters deposition on a substrate. Detailed descriptions and working of the components of the system are presented. For the characterization of the nanocluster source and associated mass filter for size selected clusters, the dependence of output performance as a function of aggregation length, sputter gas flow and magnetron power of the cluster source have been studied. Copper nanoclusters deposited on Silicon (100) surface and on transmission electron microscope grids are, respectively, studied with scanning electron microscopy and transmission electron microscopy for the morphology.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Effect of thermal implying during ageing process of nanorods growth on the properties of zinc oxide nanorod arrays

Undoped and Sn-doped Zinc oxide (ZnO) nanostructures have been fabricated using a simple sol-gel immersion method at 95°C of growth temperature. Thermal sourced by hot plate stirrer was supplied to the solution during ageing process of nanorods growth. The results showed significant decrement in the quality of layer produced after the immersion process where the conductivity and porosity of the samples reduced significantly due to the thermal appliance. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM) electrical properties has been characterized using current voltage (I-V) measurement.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Characterizing the composition, structure, and mechanical properties of magnetron sputtering physical vapor deposition TiN and TiSiN coatings

Ti(Si)N coatings were deposited on Si wafers via magnetron sputtering physical vapor deposition technique. Scanning electron microscopy and atomic force microscopy were used to study the morphologies, grain size, and thicknesses of the different films. X-ray diffraction confirmed the formation of the titanium nitride cubic phase. X-ray photoelectron spectroscopy (XPS) was used to study the silicon and oxygen levels in the films, and high resolution XPS was used to determine the surface oxide to nitride ratios as well as the silicon–nitrogen environment. The hardness of these films was then determined with nanoindentation. It was shown that grain size and film density could be controlled by the Si level and the ion bombardment to eliminate the oxygen level in the nitride coatings, which led to the harder films. It was suggested that due to the miscibility of Si, a ternary TiSiN solid solution was formed. Stronger (200) orientation of the TiN B1-NaCl crystals was associated with increased hardness of the coatings. In conclusion, this crystalline structure was preserved after incorporating Si.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The influence of deposition conditions and bilayer thickness on physical-mechanical properties of CA-PVD multilayer ZrN/CrN coatings

Highlights: • Multilayer ZrN/CrN coatings were deposited using Arc-PVD AISI321 steel substrates. • Structure, elemental and phase composition, and mechanical properties were studied. • Presence of face-centered cubic ZrN, CrN and hexagonal Cr{sub 2}N phases were detected. • All samples were heated up to 1400 °C in argon to understand thermal behavior. • Enhancement of microhardness was observed at lower values of bilayer thickness. - Abstract: ZrN/CrN multilayers have been produced by a cathodic arc technique (CA-PVD) using different depositions conditions. Microstructural and mechanical characterizations of the coatings were performed by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM with EDS), transmission electron microscopy (TEM), and Vickers microhardness tests. Variations in thermal transformation properties due to heating within the temperature range from 30 °C to 1400 °C were studied by differential scanning calorimetry (DSC) measurements. SEM and TEM observations showed that the coatings comprise a multilayered structure with nanometric grains. EDS spectra confirmed the formation of stoichiometric composition. Near-to-super stoichiometric nitrides can be suggested in certain specimens. Results of the XRD analysis revealed that the (200) and (111) planes for ZrN and Cr{sub 2}N are the most intense. Calorimetric tests showed that below a certain annealing temperature no transformations were defined. 1180 °C was found to be the value where only one-stage state transformation, presented by endothermic or exothermic reactions, took place. The highest hardness (4685HV0.025) was obtained for the coating with Λ = 140 nm, P{sub N} = 0.43 Pa, U{sub S} = −70 V.

36 MATERIALS SCIENCE↗
NASA NTRS2005

Morphology and Elemental Composition of Recent and Fossil Cyanobacteria

Cyanobacteria (cyanophyta, cyanoprokaryota, and blue-green algae) are an ancient, diverse and abundant group of photosynthetic oxygenic microorganisms. Together with other bacteria and archaea, the cyanobacteria have been the dominant life forms on Earth for over 3.5 billion years. Cyanobacteria occur in some of our planets most extreme environments - hot springs and geysers, hypersaline and alkaline lakes, hot and cold deserts, and the polar ice caps. They occur in a wide variety of morphologies. Unlike archaea and other bacteria, which are typically classified in pure culture by their physiological, biochemical and phylogenetic properties, the cyanobacteria have historically been classified based upon their size and morphological characteristics. These include the presence or absence of heterocysts, sheath, uniseriate or multiseriate trichomes, true or false branching, arrangement of thylakoids, reproduction by akinetes, binary fission, hormogonia, fragmentation, presence/absence of motility etc. Their antiquity, distribution, structural and chemical differentiation, diversity, morphological complexity and large size compared to most other bacteria, makes the cyanobacteria ideal candidates for morphological biomarkers in returned Astromaterials. We have obtained optical (nomarski and phase contrast)/fluorescent (blue and green excitation) microscopy images using an Olympus BX60 compound microscope and Field Emission Scanning Electron Microscopy images and EDAX elemental compositions of living and fossil cyanobacteria. The S-4000 Hitachi Field Emission Scanning Electron Microscope (FESEM) has been used to investigate microfossils in freshly fractured interior surfaces of terrestrial rocks and the cells, hormogonia, sheaths and trichomes of recent filamentous cyanobacteria. We present Fluorescent and FESEM Secondary and Backscattered Electron images and associated EDAX elemental analyses of recent and fossil cyanobacteria, concentrating on representatives of the genera Calothnx, Leptolyngbya, Lyngbya, Planktolyngbya and Oscillatoria.

SaintAmand, Ann↗
DOE OSTI2021

Effect of docetaxel on mechanical properties of ovarian cancer cells

Docetaxel could inhibit the proliferation of tumor cells by targeting microtubules. The extension of cellular microtubules plays an important role in the invasion and metastasis of tumor cells. This paper aims to study the distribution and mechanical properties of cytoskeletal proteins with low concentration of docetaxel. MTT assay was used to detect the minimum drug activity concentration of docetaxel on SKOV-3 cells, fluorescence staining was used to analyze the distribution of cytoskeleton proteins, scanning electron microscopy(SEM) was used to observe the morphology of single cells, and atomic force microscopy(AFM) was used to determine the microstructure and mechanical properties of cells. The results showed that the IC{sub 10} of docetaxel was 1 ng/ml. Docetaxel can effectively inhibit the formation of cell pseudopodia, hinder the indirectness between cells, reduce the cell extension area, and make the cells malformed. In addition, when AFM analyzes the effects of drugs on cell microstructure and mechanical properties, the average cell surface roughness and cell height are positively correlated with the concentration of docetaxel. Especially when the concentration was 100 ng/ml, the adhesion decreased by 37.04% and Young's modulus increased by 1.57 times compared with the control group. This may be because docetaxel leads to microtubule remodeling and membrane protein aggregation, which affects cell microstructure and increases cell strength, leading to significant changes in the mechanical properties of ovarian cells. This is of great significance to the study of the formation mechanism of tumor cell invasion and migration activities mediated by actin.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Incorporation of Er{sup 3+} ions into an amorphous matrix of Cd{sub 2}V{sub 2}O{sub 7} containing crystalline CdO nanoparticles

Er{sup 3+} ions have been introduced into a matrix of Cd{sub 2}V{sub 2}O{sub 7} using a conventional melt-quenching method. X-ray diffraction results indicate that a material constituted of CdO nanocrystals of ∼40 nm embedded within the amorphous Cd{sub 2}V{sub 2}O{sub 7} matrix was fabricated. The presence of such nanocrystals was confirmed by transmission electron microscopy. Raman spectroscopy measurements confirm that the amorphous matrix is composed by Cd{sub 2}V{sub 2}O{sub 7}. The band gap obtained by optical absorption is 2.84 eV. From the photoluminescence spectrum the electronic transitions such as ({sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}) → {sup 4}I{sub 15/2} and {sup 4}S{sub 3/2} → {sup 4}I{sub 13/2} corresponding to Er{sup 3+} were observed. Thermally activated transport was observed by dark conductivity measurements taken from room temperature to 450 K. The morphology and chemical composition of the sample were determined by scanning electron microscopy and energy dispersive spectroscopy, respectively.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Super-resolving microscopy images of Li-ion electrodes for fine-feature quantification using generative adversarial networks

Abstract For a deeper understanding of the functional behavior of energy materials, it is necessary to investigate their microstructure, e.g., via imaging techniques like scanning electron microscopy (SEM). However, active materials are often heterogeneous, necessitating quantification of features over large volumes to achieve representativity which often requires reduced resolution for large fields of view. Cracks within Li-ion electrode particles are an example of fine features, representative quantification of which requires large volumes of tens of particles. To overcome the trade-off between the imaged volume of the material and the resolution achieved, we deploy generative adversarial networks (GAN), namely SRGANs, to super-resolve SEM images of cracked cathode materials. A quantitative analysis indicates that SRGANs outperform various other networks for crack detection within aged cathode particles. This makes GANs viable for performing super-resolution on microscopy images for mitigating the trade-off between resolution and field of view, thus enabling representative quantification of fine features.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2015

Influence of leaching on surface composition, microstructure, and valence band of single grain icosahedral Al-Cu-Fe quasicrystal

The use of quasicrystals as precursors to catalysts for the steam reforming of methanol is potentially one of the most important applications of these new materials. To develop application as a technology requires a detailed understanding of the microscopic behavior of the catalyst. Here, we report the effect of leaching treatments on the surface microstructure, chemical composition, and valence band of the icosahedral (i-) Al-Cu-Fe quasicrystal in an attempt to prepare a model catalyst. The high symmetry fivefold surface of a single grain i-Al-Cu-Fe quasicrystal was leached with NaOH solution for varying times, and the resulting surface was characterized by x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The leaching treatments preferentially remove Al producing a capping layer consisting of Fe and Cu oxides. The subsurface layer contains elemental Fe and Cu in addition to the oxides. The quasicrystalline bulk structure beneath remains unchanged. The subsurface gradually becomes Fe{sub 3}O{sub 4} rich with increasing leaching time. The surface after leaching exhibits micron sized dodecahedral cavities due to preferential leaching along the fivefold axis. Nanoparticles of the transition metals and their oxides are precipitated on the surface after leaching. The size of the nanoparticles is estimated by high resolution transmission microscopy to be 5-20 nm, which is in agreement with the AFM results. Selected area electron diffraction (SAED) confirms the crystalline nature of the nanoparticles. SAED further reveals the formation of an interface between the high atomic density lattice planes of nanoparticles and the quasicrystal. These results provide an important insight into the preparation of model catalysts of nanoparticles for steam reforming of methanol.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Effect of reactor temperature on direct growth of carbon nanomaterials on stainless steel

Currently, carbon nanomaterials (CNMs) are widely used for various applications due to their extraordinary electrical, thermal and mechanical properties. In this work, CNMs were directly grown on the stainless steel (SS316) via chemical vapor deposition (CVD). Acetone was used as a carbon source and argon was used as carrier gas, to transport the acetone vapor into the reactor when the reaction occurred. Different reactor temperature such as 700, 750, 800, 850 and 900 °C were used to study their effect on CNMs growth. The growth time and argon flow rate were fixed at 30 minutes and 200 ml/min, respectively. Characterization of the morphology of the SS316 surface after CNMs growth using Scanning Electron Microscopy (SEM) showed that the diameter of grown-CNMs increased with the reactor temperature. Energy Dispersive X-ray (EDX) was used to analyze the chemical composition of the SS316 before and after CNMs growth, where the results showed that reduction of catalyst elements such as iron (Fe) and nickel (Ni) at high temperature (700 – 900 °C). Atomic Force Microscopy (AFM) analysis showed that the nano-sized hills were in the range from 21 to 80 nm. The best reactor temperature to produce CNMs was at 800 °C.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Unusual flat and extended morphology of intercalated Cu under MoS 2

We report a general method was developed to intercalate metals under layered materials through a controlled density of sputtered defects. The method has already been applied to study a range of metals intercalated under graphite, and different types of morphologies were realized. In the current work, we extend the method to the study of intercalation under MoS 2 , noting that work on this system is rather limited. We use Cu as the prototype metal for comparison with Cu intercalation under graphite. Although the growth conditions needed for intercalation under graphite and MoS 2 are similar, the type of intercalated phases is very different. Each Cu island that nucleates on top of MoS 2 during Cu deposition provides material that is transferred below MoS 2 through sputtered defects under the island base; this transfer results in a uniform intercalated Cu “carpet” morphology that extends over the mesoscale. On the contrary, Cu intercalation under graphite results in well separated, compact islands formed by monomer detachment from small Cu islands on top and transfer below through defects far from the islands. The structural techniques (scanning electron microscopy and atomic force microscopy) and spectroscopic techniques (x-ray photoelectron spectroscopy and energy-dispersive spectroscopy) are used for the characterization of the intercalated Cu layer.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

High-quality graphene grown on polycrystalline PtRh{sub 20} alloy foils by low pressure chemical vapor deposition and its electrical transport properties

High-quality continuous uniform monolayer graphene was grown on polycrystalline PtRh{sub 20} alloy foils by low pressure chemical vapor deposition. The morphology of graphene was investigated by Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. Analysis results confirm that high quality single-layer graphene was fabricated on PtRh{sub 20} foil at 1050 °C using a lower flux of methane under low pressure. Graphene films were transferred onto the SiO{sub 2}/Si substrate by the bubbling transfer method. The mobility of a test field effect transistor made of the graphene grown on PtRh{sub 20} was measured and reckoned at room temperature, showing that the carrier mobility was about 4000 cm{sup 2} V{sup −1} s{sup −1}. The results indicate that desired quality of single-layer graphene grown on PtRh{sub 20} foils can be obtained by tuning reaction conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Characterization of bulk stainless steel joints developed through microwave hybrid heating

Processing of metallic materials through microwave heating is a challenging area of research. In the present work, joining of stainless steel-316 to stainless steel-316 in the bulk form has been carried out by placing stainless steel-316 powder at the interface and through targeted heating using microwave hybrid heating. The trials were carried out in a multimode microwave applicator at a frequency of 2.45 GHz and power 900 W. The developed joints were characterized using X-ray diffraction, field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscope and measurement of Vicker's microhardness, porosity and tensile strength. The X-ray diffraction spectrum of the developed joint shows the presence of chromium carbide, iron carbide and iron silicide phases that eventually contribute to enhancement of the microhardness of the joint. The scanning electron microscope micrographs confirm classical metallurgical bonding between the substrate and the interface (molten powder) layer; the epitaxial growth rate was observed adjacent to the fusion zone. The average observed Vicker's microhardness in the joint zone on the grain boundary was significantly higher than that inside the grains due to the presence of various hard phases at the grain boundaries. Evaluation of the tensile strength of the joints showed an average ultimate tensile strength of 425.0 MPa with an average elongation of 9.44%. - Highlights: • Joining of stainless steel (SS-316) plates using microwave hybrid heating • Epitaxial growth rate observed adjacent to the fusion zone of welded joint • The ultimate tensile strength of the order of 425.0 MPa with 9.44% elongation.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Modified chemical synthesis of porous α-Sm{sub 2}S{sub 3} thin films

Highlights: • A novel chemical route to prepare α-Sm{sub 2}S{sub 3} thin films. • A porous honeycomb like morphology of the α-Sm{sub 2}S{sub 3} thin film. • An application of α-Sm{sub 2}S{sub 3} thin film toward its supercapacitive behaviour. - Abstract: The paper reports synthesis of porous α-Sm{sub 2}S{sub 3} thin films using modified chemical synthesis, also known as successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), wettability and ultraviolet–visible spectroscopy (UV–vis) techniques are used for the study of structural, elemental, morphological and optical properties of α-Sm{sub 2}S{sub 3} films. An orthorhombic crystal structure of α-Sm{sub 2}S{sub 3} is resulted from XRD study. The SEM and AFM observations showed highly porous α-Sm{sub 2}S{sub 3} film surface. An optical band gap of 2.50 eV is estimated from optical absorption spectrum. The porous α-Sm{sub 2}S{sub 3} thin film tuned for supercapacitive behaviour using cyclic voltammetry and galvanostatic charge discharge showed a specific capacitance and energy density of 294 Fg{sup –1} and 48.9 kW kg{sup –1}, respectively in 1 M LiClO{sub 4}–propylene carbonate electrolyte.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Shape stabilised phase change materials (SSPCMs): High density polyethylene and hydrocarbon waxes

Shape stabilised phase change materials (SSPCMs) based on high density polyethylene (HDPE) with high (HPW, T{sub m}=56-58 °C) and low (L-PW, T{sub m}=18-23 °C) melting point waxes were prepared by melt-mixing in a twin-screw extruder and their potential in latent heat thermal energy storage (LHTES) applications for housing assessed. The structure and morphology of these blends were investigated by scanning electron microscopy (SEM). Both H-PW and L-PW were uniformly distributed throughout the HDPE matrix. The melting point and latent heat of the SSPCMs were determined by differential scanning calorimetry (DSC). The results demonstrated that both H-PW and L-PW have a plasticisation effect on the HDPE matrix. The tensile and flexural properties of the samples were measured at room temperature (RT, 20±2 °C) and 70 °C, respectively. All mechanical properties of HDPE/H-PW and HDPE/L-PW blends decreased from RT to 70 °C. In all instances at RT, modulus and stress, irrespective of the mode of deformation was greater for the HDPE/H-PW blends. However, at 70 °C, there was no significant difference in mechanical properties between the HDPE/H-PW and HDPE/L-PW blends.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Novel Tough Crystalline Blends of Polylactide with Ethylene Glycol Derivative of POSS

Blending of polylactide (PLA) with low stereoregularity and polyhedral oligomeric silsesquioxane grafted with arms of poly(ethylene glycol) methyl ether, acting as a plasticizer, allowed us previously to obtain a novel stable elastomeric-like material. The present contribution focuses on the properties of semi-crystalline PLA plasticized with this compound. Melt blends of PLA with 5–15 wt% of the plasticizer, were compression molded, quenched and annealed, which enabled cold-crystallization. The glass transition temperature of the blends and their drawability depended on their crystallinity and plasticizer content. The best ductility was reached at the plasticizer content of 15 wt%; the achieved strain at break was 6.5 (650%) and 1.3 (130%), for the quenched and annealed material, respectively. The latter value exceeded 20 times the strain at break of neat crystalline PLA. The tensile toughness of the annealed 15 wt% blend was 12 times larger than that of crystalline PLA. Moreover, annealing of 15 wt% blend improved its yield strength by 40%. Despite the two peaks of the loss modulus, indicating the two glass transitions in this blend, no heterogeneities were found by scanning electron microscopy, indicating that the plasticizer enriched phase formed instead of distinct inclusions of the plasticizer.

36 MATERIALS SCIENCE↗
DOE OSTI2016

On a reduction in cracking upon the growth of AlN on Si substrates by hydride vapor-phase epitaxy

The main problem of the epitaxial growth of thick AlN layers on a Si substrate consists in the formation of cracks, which complicates the application of structures of this kind in the fabrication of semiconductor devices. The possibility of obtaining crack-free AlN layers with a thickness exceeding 1 μm and a mirror- smooth surface by hydride vapor-phase epitaxy is demonstrated. The properties of the layers are studied by X-diffraction analysis, optical and scanning electron microscopy, and Raman spectroscopy.

36 MATERIALS SCIENCE↗