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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 1,639 records · Page 91
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Characterization of Additively Manufacture GRCop-42 and GRCop-84

GRCop-42 (Cu-4 at.% Cr-2 at.% Nb) is a copper-based alloy optimized for high temperature, high thermal conductivity applications such as regenerative cooled rocket engine liners. For this application, it is important to minimize contamination such as trace elements and ceramic inclusions. NASA initiated a series of ten builds by eight companies to assess the repeatability of GRCop-42 between vendors and machines. Utilizing inductively coupled plasma – atomic emission spectroscopy (ICP-AES) and energy dispersive spectroscopy (EDS) techniques allowed for identification of contaminants and quantification of their chemistry. In addition, additive manufacturing (AM) creates a unique microstructure that is often highly textured in the build (Z) direction. Electron backscattered diffraction (EBSD) was used to begin quantifying the degree of crystallographic texture in the copper matrix grains. It was also used to identify the crystallographic form of Cr2Nb, the main strengthening phase, present in the samples. Results showed the presence of ceramic inclusions, highly textured grains, and both the low and high temperature phases of Cr2Nb being present.

copper↗
NASA NTRSDate not supplied

Terrestrial Analogue Studies from ISRO’s Venus Mission Perspective: Polarimetric Radar Properties of Hawaiian Lava Flows

Detection of present and past volcanism on Venus is one of the major goals of the proposed ISRO’s Venus orbiter mission. The S-band, high-resolution (40 m/pixel) fully Polarimetric Synthetic Aperture Radar (PolSAR) instrument on this mission [1] may have the capabilities to detect volcanism within the mission lifetime using repeated PolSAR imagery, and possibly SAR Interferometry (InSAR, experimental mode). The global mapping efforts of Venus by Magellan mission has enabled comprehensive mapping of lava flows and indicated that Venus has an extensive history of volcanism, the ages of which are largely unknown (e.g. [2]). While Magellan radar emissivity data (e.g. [3, 4]) and Near Infrared emissivity data from VIRTIS [5] suggested the occurrence of recent episodes of volcanic activity (e.g. Maat Mons and Ganis Chasma), as well as the presence of stratigraphically young lava flows (e.g. Idunn Mons), measuring changes in radar backscatter amplitude alone to identify lava flows has many challenges. Although very large changes in the shape of the terrain can be observed in radar backscatter amplitude changes (e.g. [6]), smaller, or relatively flat lava flows are difficult to detect. Previous terrestrial studies suggest that PolSAR and InSAR techniques are very effective for mapping lava flows (e.g. [7-9]), and can be used when changes cannot be distinguished in radar backscatter images. We use the unvegetated lava flows on Hawaiʻi island as a terrestrial analogue to study Venus lava flows for the following reasons: (a) It is extensively studied at several wavelengths commonly used in remote sensing studies (including PolSAR and InSAR methods); and (b) it is a volcanically active area with new lava flows frequently covering older emplaced flows. To investigate the surface roughness, texture, and fine-grained mantling associated with Mauna Loa and Kilauea lava flows, we utilize C- and L-band PolSAR datasets obtained from RISAT-1A (EOS-4) and ALOS PALSAR missions respectively. In particular, we will use the quad-polarized backscatter and polarimetric parameters to characterize the texture of the terrestrial lava flows to understand whether the Venus crust is continuously disrupted during flow emplacement. While some previous studies (e.g. [10, 11]) suggested that surface roughness of most of the Venus flows is comparable to that of terrestrial pāhoehoe flows, other studies indicated that fractal dimensions of some large lava flows on Venus imply high eruption rates which favour the formation of a’a flows (e.g. [12]). We will also analyse the terrestrial flows for the presence/absence of pyroclastic mantling as radar-bright diffuse deposits near the summit regions of some coronae on Venus have been proposed to be young pyroclastics, and possible evidence of a renewed epoch of mantle volcanism that taps into deeper volatiles [13]. A recent study using EOS-4 RISAT-1 data of a part of fresh Mauna Loa lava flows (2022 eruption) emphasizes the ability of fully polarimetric SAR data to understand the diversity of physical properties (e.g. texture and morphology) associated with them (Sreejith et al. 2024); and we will apply similar methods to the PolSAR data obtained from ISRO’s Venus mission for our proposed objectives.

Sriram S Bhiravarasu↗
DOE OSTI2014

Micromechanical Behavior of Solid-Solution-Strengthened Mg-1wt.%Al Alloy Investigated by In-Situ Neutron Diffraction

In-situ neutron-diffraction experiments were employed to investigate the micromechanical behavior of solid-solution-strengthened Mg-1wt.%Al alloy. Two starting textures were used: 1) as-extruded then solutionized texture, T1, in which the basal poles of most grains are tilted around 70~85 from the extrusion axis, and 2) a reoriented texture, T2, in which the basal poles of most grains are tilted around 10~20 from the extrusion axis. Lattice strains and diffraction peak intensity variations were measured in situ during loading-unloading cycles in uniaxial tension. Twinning activities and stress states for various grain orientations were revealed. The results show that the soft grain orientations, favorably oriented for either extension twinning or basal slip, exhibit the stress relaxation, resulting in the compressive residual strain after unloading. On the other hand, the hard grain orientations, unfavorably oriented for both extension twinning and basal slip, carry more applied load, leading to much higher lattice strains during loading followed by tensile residual strains upon unloading.

Lee, Sooyeol↗
DOE OSTI2014

Buffer layers for REBCO films for use in superconducting devices

A superconducting article includes a substrate having a biaxially textured surface. A biaxially textured buffer layer, which can be a cap layer, is supported by the substrate. The buffer layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different transition metal cations. A biaxially textured superconductor layer is deposited so as to be supported by the buffer layer. A method of making a superconducting article is also disclosed.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Surface dimpling on rotating work piece using rotation cutting tool

A combined method of machining and applying a surface texture to a work piece and a tool assembly that is capable of machining and applying a surface texture to a work piece are disclosed. The disclosed method includes machining portions of an outer or inner surface of a work piece. The method also includes rotating the work piece in front of a rotating cutting tool and engaging the outer surface of the work piece with the rotating cutting tool to cut dimples in the outer surface of the work piece. The disclosed tool assembly includes a rotating cutting tool coupled to an end of a rotational machining device, such as a lathe. The same tool assembly can be used to both machine the work piece and apply a surface texture to the work piece without unloading the work piece from the tool assembly.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Thin film photovoltaic devices with microlens arrays

Textured transparent layers are formed on the incident light receiving surface of thin film solar cells to increase their efficiency by altering the incident light path and capturing a portion of the light reflected at the MLA. The textured transparent layer is an array of lenses of micrometer proportions such as hemispheres, hemi-ellipsoids, partial-spheres, partial-ellipsoids, cones, pyramids, prisms, half cylinders, or combinations thereof. A method of forming the textured transparent layer to the light incident surface of the solar cell is by forming an array of lenses from a photocurable resin and its subsequent curing. The photocurable resin can be applied by inkjet printing or can be applied by roll to roll imprinting or stamping with a mold.

14 SOLAR ENERGY↗
DOE OSTI2025

Hyperspectral Cathodoluminescence of Bastnäsite at the Mountain Pass Mine, USA: Implications for REE Mineralisation and Mining

This study uses micro-analyses including hyperspectral cathodoluminescence to image and obtain mineral spectral to help evaluate REE deportment via from Mountain Pass Mine in California. It presents the first known CL-based spectra for bastnäsite, new information regarding baryte CL spectra, providing insights on the coeval and spatial relationship between REE, Ba, and S in carbonatite systems. Bastnäsite, baryte, and monazite are often intergrown in both brecciated, “blue ore” samples, and these minerals occur as an apparent intercumulus texture in the dolomite-rich, “white ore” samples. Bastnäsite luminescence is present, but very low compared to baryte in the visible spectrum. Bastnäsite illustrates some textural variability related to its main luminescent peak ~1.4 eV, which is indicative of Nd3+. It also exhibits several other small peaks comprised of multiple activators related to various REE, including Ce3+, Sm3+, Eu3+, and potentially Eu2+. Baryte displays textures of variable complexity but often with darker rims near crystal margins. It luminesces mainly at 1.4-1.52 eV, 2.05 eV, and 3.59-4.08 eV. The 2.05 eV peak is likely attributed to Ag+, but the other peaks are more enigmatic.

58 - GEOSCIENCES↗
DOE OSTI2024

Matrix polysaccharides affect preferred orientation of cellulose crystals in primary cell walls

The spatial organization and interactions of constituent components influence cell growth and determine physical and chemical properties of the cell wall, including its rigidity, flexibility, and degradability. Elucidating the interactions between cell wall polysaccharides is crucial for advancing our knowledge of how cell walls are assembled and for designing approaches to efficiently break down cell walls to produce renewable energy and biomaterials. Here, we investigated the effect of defects in the biosynthesis of cell wall components on the nanoscale organization of cellulose in primary cell walls through grazing incidence wide angle X-ray scattering (GIWAXS) measurements of hypocotyls of wild type Arabidopsis thaliana and of cellulose, pectin, and xyloglucan (hemicellulose) deficient mutants. GIWAXS reveals changes in lattice spacings, coherence lengths, and relative crystalline content for cellulose between wild type and mutant plants. In addition, X-ray pole figures constructed using GIWAXS and X-ray diffraction (XRD) rocking scans quantify an emerging measure of cellulose organization, the degree of preferred orientation (texture) of cellulose crystals with respect to the cell wall plane. Comparing X-ray pole figures from pectin-deficient and xyloglucan-deficient mutants to that of wild type plants reveals that cellulose texture is disrupted in pectin-deficient mutants, but not in xyloglucan mutants. Furthermore, our results indicate that a deficiency of pectin during cell wall biosynthesis alters cellulose organization in plant cell walls.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Structural Analysis of ZnO Nanoparticles Reinforced P(3HB-co-15 mol% 3HHx) Bioplastic Composite

Bioplastics are gaining interest due to their biodegradable and biocompatible nature which can be used as a replacement for petroleum based plastics. Poly (3-hydroxybutyrate-co-15 mol% 3-hydroxyhexanoate) [P(3HB-co-15 mol% 3HHx)]/ZnO nanoparticles (NPs) blended bioplastic films were fabricated by solution casting method using chloroform as solvent. The structural characteristics such as peak intensity analysis, crystallite size, dislocation density, and texture coefficient of ZnO NPs mixed P(3HB-co-15 mol% 3HHx) samples were studied using X-Ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR) analyses. It is clear from the XRD analyses that the crystallinity of P(3HB-co-15 mol% 3HHx) was decreased considerably as ZnO NPs concentration increased. The crystallite size of P(3HB-co-15 mol% 3HHx) was decreased with an increase in ZnO NPs concentration and observed within 150 nm and the dislocation density was decreased with respect to the orientation of P(3HB-co-15 mol% 3HHx) crystals. Simultaneously, the structural properties of ZnO NPs in P(3HB-co-15 mol% 3HHx) matrix were affected noticeably with respect to the ZnO NPs and copolymer concentrations. The characteristic peak positions from FTIR spectra of P(3HB-co-15 mol% 3HHx) copolymer shifted towards higher frequency and evidenced the existence of structural defects. Overall, it was found from both XRD and FTIR analyses that the presence of ZnO NPs affected the crystallinity of P(3HB-co-15 mol% 3HHx) copolymer due to the formation of intermolecular bonds, which restricted the preferential orientation of P(3HB-co-15 mol% 3HHx) molecules which was observed from the texture coefficient analyses. Based on these observations, ZnO NPs at low concentrations can be used with P(3HB-co-15 mol% 3HHx) copolymer effectively and the resulting composite may be used for packaging application.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Effects of Nd Addition on the Microstructure and Mechanical Properties of Extruded Mg-6Gd-2.5Y-0.5Zr Alloy

The microstructure, age-hardening behavior, mechanical properties and texture of extruded Mg-6Gd-2.5Y-0.5Zr alloys with various additions of Nd have been investigated through optical microscopy, x-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron back-scattered diffraction, hardness and tensile tests. The results indicate that the number of second-phase particles in the as-extruded alloys increases (especially with the addition of 1.5 wt.% Nd), and the amount of the strengthening β′ phase in the peak-aged sample initially increases, and then decreases when the content of Nd increases above 1.0 wt.%. The precipitation of second-phase particles in the extrusion process weakens the age strengthening. The peak-aged Mg-6Gd-2.5Y-1Nd-0.5Zr alloy shows a maximum yield strength of 259 MPa and an ultimate tensile strength of 350 MPa, which can be attributed to the finely dispersed strengthening β′ phase. All as-extruded alloys exhibit that (0001) planes are aligned perpendicular to the extrusion direction, and the maximum intensity of the texture increases gradually with Nd addition.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructure Characteristic and Mechanical Properties of High-Strength Mg-Nd-Zn-Zr Alloy Seamless Tube Produced by Integrated Extrusion

Large size seamless tubes of Mg-3.0Nd-0.4Zn-0.4Zr alloy (NZ30K, in weight percent) were prepared by integrating backward extrusion with forward extrusion. Microstructure, mechanical properties, aging behavior and texture of the tubes were investigated. The microstructure of as-extruded tube is characterized by the blend of considerably elongated grains and fine equiaxed grains. The maximum values of yield strength and ultimate tensile strength, i.e., 191 and 245 MPa, were obtained in the as-extruded tubes, and these values were increased to 212 and 267 MPa in the peak-aged tubes (T5), implying an increasing ratio of 9 and 11%, respectively. The peak value of the Vickers’ micro-hardness of the NZ30K tubes extruded at 673, 723 and 753 K are 66, 64 and 60 (kilogram-force per square millimeter), respectively. The texture of NZ30K tube is weak, the primary mechanism behind which is suggested to be the particle-induced nucleation responsible for the promotion of recrystallization.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of Single-Point Incremental Force Process Parameters on Forming Characteristics and Microstructure Evolution of AA-6061 Alloy Sheet

Single-point incremental forming (SPIF) process comprises a set of process variables, such as forming tool diameter, vertical pitch, spindle rotation speed, and tool velocity, which may affect the forming behavior of the sheet to be deformed. The objective of this work is to study the effect of SPIF process parameters on forming characteristics and microstructure development for the AA-6061 (T6) aluminum alloy sheet. The SPIF experiments and finite element (FE) simulations were performed at different process parameters to achieve conical shapes from the AA-6061 blanks. The effect of process parameters on forming forces, thickness uniformity in wall region of the cone and surface roughness of the blank was analyzed. A detailed microstructure study was performed to analyze the effect of process variables on microstructure and texture evolution during the SPIF process. This study reveals that the process parameters are likely to influence the texture development especially at high tool diameter and vertical pitch values. Therefore, suitability and consequences of using different combinations of tool diameter and vertical pitch values are discussed for AA-6061 alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Solid state dewetting of thin plasmonic films under focused cw-laser irradiation

Elevated temperatures and large thermal gradients are a significant source of component failure in microelectronics, and is the limiting factor in heat-assisted magnetic recording (HAMR). Here, we have investigated the effect of solid-state dewetting in Au thin films, as a function of local temperature, film thickness, and substrate adhesion. In this work, a localised temperature rise is induced in thin (≤ 50 nm) polycrystalline Au films on SiO 2 substrates via focused continuous-wave laser irradiation at 488 nm. The magnitude and distribution of the total temperature rise is measured using CCD-based thermoreflectance. This also allows a sensitive measurement of the temperature at which dewetting occurs, showing that for thin (≤ 50 nm) Au films without adhesion layers, rapid dewetting can occur at temperatures as low as 50° C. The time decay of the reflected light from the illuminating laser is used to monitor locally the dynamics of solid state dewetting. TEM diffraction analysis shows significant changes in the microstructure and crystallographic texture of the films as far as 10 µm away from the illuminated area. The use of a thin metallic adhesion layer (such as Ti or Cr) is shown to significantly improve the adhesion of the Au to the substrate and reduce the tendency towards dewetting, but does not entirely protect it from changes to the crystallographic texture.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Temperature-dependent dynamic fouling on superhydrophobic and slippery nonwetting copper surfaces

Bioinspired, superhydrophobic and slippery liquid infused surfaces that offer nonwetting characteristics have been explored in recent years for fouling mitigation. However, most of the studies are in the context of biofouling or under static immersion at ambient temperature conditions that are not reflective of the dynamic flow environment in practice. This article presents, for the first time, a systematic study of dynamic fouling of superhydrophobic (SHS) and slippery lubricant-infused surfaces (LIS) over a range of flow and temperature conditions. In this work, copper metallic surfaces were textured via electrodeposition or etching and further functionalized to achieve SHS and, additionally, infiltrated with a lubricant to fabricate LIS. The nonwetting surfaces were studied for their fouling behavior in a rotating Couette flow of a supersaturated calcium sulfate solution at different rotational speed and temperature. Fouling mineral mass accumulation on the different surfaces was measured as a function of time over a period of days using inductively coupled plasma mass spectroscopy and the fouled surfaces were investigated using scanning electron microscopy. Both SHS and LIS showed superior anti-scaling performance at all ranges of variables. An analytical Hill-Langmuir model is presented, for the first time, to describe the time evolution of scaling within 20% accuracy over the range of parameters studied. The study is the first to juxtapose two surface texturing methods, electrodeposition and etching, and two nonwetting surface types, SHS and LIS, subject to a common suite of experiments to elucidate fundamental understanding of mineral fouling on nonwetting surfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical constitutive models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. To improve upon this approach, a microstructurally-based zirconium alloy mechanical deformation analysis capability is being developed within the United States Department of Energy Consortium for Advanced Simulation of Light Water Reactors (CASL). Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tomé [1], has been coupled with the BISON engineering scale fuel performance code to represent the mechanistic material processes controlling the deformation behavior of light water reactor (LWR) cladding. A critical component of VPSC is the representation of the crystallographic nature (defect and dislocation movement) and orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. A future goal is for VPSC to obtain information on reaction rate kinetics from atomistic calculations to inform the defect and dislocation behavior models described in VPSC. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON and provides initial results utilizing the coupled functionality.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Engineering grain boundary anisotropy to elucidate grain growth behavior in alumina

Current grain growth models have evolved to account for the relationship between grain boundary energy/mobility anisotropy and the five degrees of grain boundary character. However, the role of grain boundary networks on overall growth kinetics remains poorly understood. To experimentally investigate this problem, a highly textured Al 2 O 3 was fabricated by colloidal casting in a strong magnetic field to engineer a unique spatial distribution of grain boundary character. Microstructural evolution was quantified and compared to an untextured sample. From this comparison, a prevalence of (0001)/(0001) terminated grain boundaries with anisotropic networks were identified in the textured sample. These boundaries and their networks were found to be driving grain growth at a faster rate than predicted by models. These findings will allow better modelling of grain growth in real systems by experimentally exploring the impact thereon of grain boundary plane anisotropy and relative energy/mobility differences between neighboring boundaries.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Role of surface wetting on tribological behavior for laser nanotextured steel using ionic liquid lubricants

Here, this research evaluates the effect of surface wettability on the tribological performance through ball-on-flat tribology testing. The substrate material, M2 tool steel, is laser processed and then functionalized with fluorocarbon and nitrile chemistry to achieve distinct oleophobicity and oleophilicity, respectively, but with a similar nanoscale surface texture. The baseline lubricant is poly-alpha-olefin (PAO) oil, and ionic liquids (ILs) are used as additives for this study. The interaction between the nanoscale textured steel surface and ionic liquid-based oils is investigated. A set of reciprocating wear tests are performed to investigate the tribological behavior of the tribo-system consisting of the surface-engineered, flat M2 tool steel specimen and a standard, surface-polished steel ball. Results show that the oleophobic flat surface results in a lower friction, while the oleophilic surface modification leads to a better wear protection to the flat surface. Ammonium-based IL provides the highest friction reduction, while the phosphonium-based ILs provide an improved wear protection.

36 MATERIALS SCIENCE↗