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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Characterization and properties of controlled nucleation thermochemical deposited /CNTD/ silicon carbide

Results are presented for an investigation designed to characterize the microstructure of controlled nucleation thermomechanical deposition (CNTD) produced SiC material with respect to grain structure, stoichiometry, phase analysis, etc., and to evaluate the room-temperature and high-temperature fracture and oxidation behavior. By using the CNTD process, ultrafine-grained SiC is deposited on tungsten wires as substrates, with superior surface smoothness and without the macrocolumnar growth commonly observed in conventional CVD materials. The results suggest that the high-purity, fully dense, and stable grain size SiC material produced by CNTD shows potential for high-temperature structural applications, provided that pertinent problems are resolved.

Dutta, S.↗
NASA NTRS2002

Micro-Raman Analysis of Irradiated Diamond Films

Owing to its unique and robust physical properties, diamond is a much sought after material for use in advanced technologies such as Microelectromechanical Systems (MEMS). The volume and weight savings promised by MEMS-based devices are of particular interest to spaceflight applications. However, much basic materials science research remains to be completed in this field. Results of micro-Raman analysis of proton (1015 - 1017 H+/cm2 doses) irradiated chemical vapor deposited (CVD) diamond reveals that the microstructure is retained even after high radiation exposure.

Newton, R. L.↗
NASA NTRSDate not supplied

An Integrated Recursive Framework for Arbitrarily Multiscale and Multi-fidelity Modeling

The NASA Multiscale Analysis Tool (NAMSAT) serves as a state-of-the-art, “plug and play,” massively multiscale modeling (M3) platform for hierarchical materials and structures. The development of NASMAT has focused on modularity, upgradability and maintainability, interoperability, and utility. Application Program Interfaces (APIs) have been developed to facilitate the integration NASMAT into other programs (commercial, research, and user-defined) as well as the integration of other codes into NASMAT. NASMAT is an integrated, recursive platform that seamlessly allows for an arbitrary number of scales, and a variety of modeling fidelity, in a single, non-linear analysis. Thus, the macroscopic response of a material can be directly linked to the behavior of the microstructure(s), including subscale defects, making it a suitable tool for integrated computational materials engineering (ICME) because . Examples using NASMAT for simulation of polycrystalline metals at elevated temperatures will be presented.

Multiscale Modeling↗
DOE OSTI2019

Determination of the structure-processing-properties relationship of Fe-6.5wt%Si

The role of Fe-6.5wt%Si as a soft magnetic material in motor and power generation will continue to increase as power and efficiency demands keep increasing due to high silicon steel’s superior magnetic and electrical properties when operated at high frequencies. However, the presence of brittle phases creates challenges for mass production of the materials and for machining the materials into parts with demanding geometries. Understanding the processing parameters controlling the presence of the brittle phases is necessary to promote high silicon steels as the superior soft magnetic material. This research pioneers the use of in-situ cooling rate thermal imaging analysis and a 2D Laue x-ray detector to quantify the relationship among processing parameters, final microstructure of melt-spun ribbons and the associated physical properties. These techniques reveal the superlattice peaks of the ordered B2/D03 phases separating them from the background A2 phase. Utilizing a variety of techniques investigating mechanical, electrical, and magnetic properties’ correlation to crystal structure alongside processing parameters a time temperature transformation curve can be generated.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

The Influence of Temperature on the Cyclic Properties of the Transversely Isotropic Nanocomposite System Under Kinematic Harmonic Loading

A micromechanical model is developed to determine the effective inelastic properties of nanocomposites under monoharmonic deformation by taking into account the detailed microstructural geometries and constitutive models of the constituents. By using the correspondence principle in viscoelasticity and the modified Mori–Tanaka method, the effects of interface between the inclusion and the matrix are taken into account. By applying the developed model, we perform the numerical analysis aimed at the determination of complex moduli for a polymeric nanocomposite reinforced with nanofibers composed from carbon nanotubes under the isothermal conditions. The dependences of complex moduli on temperature and the amplitude of strain intensity are analyzed. The composites reinforced with unidirectionally aligned nanofibers are considered. The accumulated results demonstrate a strong dependence of the storage and loss moduli on temperature within a broad temperature range. The storage and loss moduli are found to monotonically increase with the volume fraction of nanofibers. At the same time, they decrease as temperature increases. The obtained results show that the strength of material decreases as temperature increases in the elastic and inelastic regions and the inelastic behavior occurs for lower strain amplitude as temperature increases.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2011

Cu-Ce-O mixed oxides from Ce-containing layered double hydroxide precursors: Controllable preparation and catalytic performance

Cu/Zn/Al layered double hydroxide (LDH) precursors have been synthesized using an anion exchange method with anionic Ce complexes containing the dipicolinate (pyridine-2,6-dicarboxylate) ligand. Cu-Ce-O mixed oxides were obtained by calcination of the Ce-containing LDHs. The materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry-differential thermal analysis, elemental analysis, and low temperature N{sub 2} adsorption/desorption measurements. The results reveal that the inclusion of Ce has a significant effect on the specific surface area, pore structure, and chemical state of Cu in the resulting Cu-Ce-O mixed metal oxides. The resulting changes in composition and structure, particularly the interactions between Cu and Ce centers, significantly enhance the activity of the Ce-containing materials as catalysts for the oxidation of phenol by hydrogen peroxide. - Graphical Abstract: Cu-Ce-O mixed oxides calcined from [Ce(dipic){sub 3}]{sup 3-}- intercalated Cu/Zn/Al layered double hydroxides were synthesized and displayed good catalytic performances in phenol oxidation due to the Cu-Ce interactions. Highlights: Black-Right-Pointing-Pointer [Ce(dipic){sub 3}]{sup 3-}-intercalated Cu/Zn/Al layered double hydroxides were synthesized. Black-Right-Pointing-Pointer Cu-Ce-O mixed oxides derivated from the LDHs were characterized as catalysts. Black-Right-Pointing-Pointer Presence of Ce influenced physicochemical property and catalytic performance. Black-Right-Pointing-Pointer Cu-Ce interaction was largely responsible for enhanced catalytic ability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2019

Coordinated Analysis of an Ion Irradiated Carbonaceous Chondrite Suggests Complex Space Weathering Effects

Surfaces of airless planetary bodies are exposed to micrometeorite bombardment and solar wind irradiation which alter the microstructural, compositional, and optical properties of regoliths over time. These processes are collectively known as space weathering, and they complicate the interpretation of remote sensing data and the subsequent characterization of airless surfaces. Within the next 5 years, NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) and JAXA (Japan Aerospace Exploration Agency)’s Hayabusa2 missions will return samples from C-type asteroids Bennu and Ryugu, respectively. Compared to the Moon and S-type asteroids, our understanding of the space weathering of C-complex asteroids is limited. In order to maximize scientific return from remote sensing data and to prepare for the analysis of returned samples from these missions, we must better understand the effects of space weathering on hydrated, organic-rich materials. We can do so by simulating these processes in the laboratory. In this study, we simulate solar wind exposure through ion irradiation of the CM2 carbonaceous chondrite Murchison - a suitable analog for C-complex asteroids. Here, we present coordinated analyses of a sample before and after ion irradiation.

Laczniak, D. L.↗
DOE OSTI2025

On the bulk compaction of brittle granular materials, part I: SeS analysis of axial compression to 4000 MPa

The bulk compaction of granular materials has been studied for decades to interpret and manage responses for soils and powder-based component fabrication, and geophysical, celestial, and ballistic impact. Their bulk or macroscopic compaction response is limited by what occurs at the granular or microstructural scale. Motivation existed to more closely examine that association specific to granular brittle materials (e.g., ceramics and glasses). That examination is offered in a series of three companion papers where Part I describes a new supplemental analysis adopted to bulk compaction response involving relatively high compaction stresses (4000 MPa). Bulk compactions of vitreous silicates and crystalline quartzes were interpreted in three ways, including that of a new analysis that considers the product of void ratio (e) and stress (S) as a function of S, hereafter referred to as “SeS analysis”. In conclusion, the SeS analysis was found to be an informative supplement to conventional bulk compaction analyses because it provides more consistent higher sensitivity for the identification of bulk density rate increase with increasing compaction (softening); a rate increase that arises from the cumulative effect of the onsets and progression of compaction-induced yielding, fracture or comminution, densification, phase change, or combinations thereof occurring at the granular or microstructural scale.

compaction↗
DOE OSTI2012

Observation of columnar microstructure in lattice-matched InAlN/GaN grown by plasma assisted molecular beam epitaxy

Nominally lattice matched InAlN/GaN was grown by plasma-assisted molecular beam epitaxy, and the intrinsic microstructure was investigated via x-ray diffraction, transmission electron microscopy, and atom probe tomography. The InAlN showed a cellular structure, which was comprised of ~10 nm wide Al-rich cores and ~1 nm In-rich InAlN intercellular boundaries. Despite the strong laterally non-uniform In distribution, both vertical and lateral lattices are unperturbed by the cellular structure, as evidenced by strong thickness fringes in on-axis ω-2θ high resolution x-ray diffraction scans, coherence lengths derived from on-axis (0002) and off-axis (10{anti 1}2) ω-2θ high resolution x-ray diffraction scans, and a modified Williamson-Hall analysis for on-axis reflections.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Phase separation during the direct powder bed fusion of SiC

Powder bed fusion (PBF) is an attractive additive manufacturing option for fabrication of SiC object with complex geometries. However, the density and microstructure controls remain a challenge. This study is aimed at understanding laser–SiC interactions, with emphasis on microstructure-processing relationships, to identify potential solutions for the process improvement. SiC tubes were fabricated by PBF of pure SiC powders without sintering additives. Further, comprehensive analysis by X-ray diffraction, Raman spectroscopy, and electron microscopy indicated that binding of SiC particles was achieved by incongruent melting of SiC to a Si/C mixture containing SiC micro- and nanocrystallites. The phase evolution under laser irradiation of SiC was explained by phase diagrams. This study uncovered the PBF SiC microstructure at different length scales and the relationship between the microstructure and the processing parameters.

36 MATERIALS SCIENCE↗
NASA NTRS1998

The Application of Nonstandard Analysis to the Study of Inviscid Shock Wave Jump Conditions

The use of conservation laws in nonconservative form for deriving shock jump conditions by Schwartz distribution theory leads to ambiguous products of generalized functions. Nonstandard analysis is used to define a class of Heaviside functions where the jump from zero to one occurs on an infinitesimal interval. These Heaviside functions differ by their microstructure near x = 0, i.e., by the nature of the rise within the infinitesimal interval it is shown that the conservation laws in nonconservative form can relate the different Heaviside functions used to define jumps in different flow parameters. There are no mathematical or logical ambiguities in the derivation of the jump conditions. An important result is that the microstructure of the Heaviside function of the jump in entropy has a positive peak greater than one within the infinitesimal interval where the jump occurs. This phenomena is known from more sophisticated studies of the structure of shock waves using viscous fluid assumption. However, the present analysis is simpler and more direct.

Farassat, F.↗
NASA NTRS2023

STXM-C-XANES, IR Microspectroscopy, and Raman Microspectroscopy Analysis of Organic Matter in the Chwichiya 002 C3.00-Ungrouped Chondrite

Chwichiya 002 is a C3.00-ungrouped carbonaceous chondrite discovered in Western Sahara in 2018. The presence of hydrated phases in Chwichiya 002 was not confirmed by XRD analysis, and only a faint water and Si-O band attributed to phyllosilicate were observed by infrared transmission spectroscopy, indicating a very low degree of aqueous alteration (Meteoritical Bulletin, 2020). The structural order of polycyclic aromatic hydrocarbons evaluated by Raman spectroscopy indicates that the effect of thermal metamorphism is less severe than in the Semarkona meteorite, an LL3.00 ordinary chondrite (Meteoritical Bulletin, 2020). Chiwichiya 002 is a very primitive carbonaceous chondrite and an important information source for the early stage of the evolution of organic matter in the solar system. In this study, we investigated the molecular structure and distribution of organic matter in Chiwichiya 002 by Carbon X-ray Absorption Near Edge Structure (C-XANES) analysis using a Scanning Transmission X-ray Microscope (STXM). The STXM-C-XANES analysis has a spatial resolution of 20~100 nm and can observe the spatial distribution of organic materials in microstructures. In addition, to investigate the degree of thermal metamorphism of the organic matter, micro-IR, and micro-Raman spectroscopic analyses were performed. In addition, the Murchison CM2 chondrite was also analyzed for comparison. To evaluate contamination during analytical procedures, antigorite, which was heated in air at 500°C for 5 hours to eliminate organic matter was also analyzed in the same manner. The samples were milled into 100 nm-thick, thin sections using a Focused Ion Beam (FIB), and C-XANES spectra were obtained using the STXM at the High Energy Accelerator Research Organization, Photon Factory (PF), BL-19B. The obtained C-XANES spectra were smoothed and then fitted with Gaussian functions using the method of Le Guillou et al. (2018). The C-XANES showed that the ratio of oxygenated functional group (ketone, phenolic) carbons in Chwichiya 002 was lower than in Murchison, whereas the ratio of aliphatic carbons was almost the same. This may reflect the low degree of aqueous alteration of Chwichiya 002. In addition, contamination peaks were detected at 287.3-287.7 eV and 288.3-288.7 eV in the C-XANES spectra of some of the antigorite samples. The source of these peaks is under investigation. Raman spectroscopic analysis showed that the intensity ratio of the D band to the G band of Chwichiya 002 was slightly higher than that of Murchison. IR absorption spectra showed aromatic absorption at 1630 cm -1 , but there was little absorption due to aliphatic C-H around 2900 cm -1 . These results suggest that the organic matter in Chwichiya 002 may be more heated than in Murchison.

Chwichiya 002↗
DOE OSTI2016

Prediction of water vapour sorption isotherms and microstructure of hardened Portland cement pastes

Water vapour sorption isotherms of cementitious materials reflect the multi-scale physical microstructure through its interaction with moisture. Our ability to understand and predict adsorption and desorption behaviour is essential in the application of modern performance-based approaches to durability analysis, along with many other areas of hygro-mechanical and hygro-chemo-mechanical behaviour. In this paper, a new physically based model for predicting water vapour sorption isotherms of arbitrary hardened Portland cement pastes is presented. Established thermodynamic principles, applied to a microstructure model that develops with hydration, provide a rational basis for predictions. Closed-form differentiable equations, along with a rational consideration of hysteresis and scanning phenomena, makes the model suitable for use in numerical moisture simulations. The microstructure model is reconciled with recently published {sup 1}H NMR and mercury intrusion porosimetry results.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are compared with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Comparison of irradiation tolerance of two MAX phases-Ti 4 AlN 3 and Ti 2 AlN

The microstructures of two MAX phases, Ti 2 AlN and Ti 4 AlN 3 , irradiated at room temperature with 70 keV He ions over a wide fluence range have been studied to reveal the dependence of MAX phase irradiation tolerance on structure. Grazing incident x-ray diffraction (GIXRD) reveals that a new set of diffraction peaks appears after ion irradiation for both MAX phases and the positions of diffraction peaks gradually shift towards lower 2θ values with increasing fluence. Transmission electron microscope characterizations show both MAX phases experience a similar structure transformation at low fluences, forming an intermediate structure. The d-spacings derived from electron diffraction analysis of intermediate structures are basically consistent with that of new peaks in GIXRD. At high fluences a nano-twinned microstructure is found in Ti 2 AlN, but no such microstructure is observed in Ti 4 AlN 3 . Based on the simulation results of electron diffractions and the irradiation responses of other MAX phases, the structure characteristics and formation mechanisms of the intermediate structure are derived and the discrepancy in the phase stability of both MAX phases at high fluences is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Advanced processing of EBSD data to distinguish the complex microstructure evolution of a Cu-Ni-Si alloy induced by fatigue

Highlights: • Microstructure investigation of the fatigue behaviour of a Cu-Ni-Si alloy • Use of ECCI and EBSD to investigate the microstructure evolution related to fatigue dislocations structures • Characterisation of local plastic accommodation through EBSD misorientation criteria - Abstract: The present work aims at identifying the evolution of the microstructure of a Cu-Ni-Si (Corson alloy) alloy after low cycle fatigue by means of advanced electron microscopy analysis techniques (SEM-ECCI, Orientation Imaging Microscopy by means of SEM-EBSD and TEM). Deep attention is paid on the material subjected to high cyclic strains where a transient cellular dislocation structure transformed into precipitate free bands. It is shown that the formation of dislocation cells leads to a high GROD and high GOSaera value and its standard deviation. However, the presence of precipitate free bands results in the low GOSarea level and its low standard deviation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Machine-learning-assisted deciphering of microstructural effects on ionic transport in composite materials: A case study of Li 7 La 3 Zr 2 O 12 -LiCoO 2

The effective diffusivity of ionic species in multiphase materials is critical for the design and function of composite materials for electrochemical energy storage. In practice, effective diffusivity depends sensitively not only on the intrinsic diffusivities of constituting materials but also on their topological arrangement; nevertheless, these coupled contributions are oversimplified in most analytical models. Here, we combine atomistically informed mesoscale modeling and machine learning (ML) analysis to unravel how such features affect effective diffusivity in two-phase composites. Using the Li 7 La 3 Zr 2 O 12 -LiCoO 2 composite solid-state battery cathode as a model system, we compute effective diffusivity for 600 distinct dense polycrystalline microstructures with different topological configurations of grains, grain boundaries, and heterointerfaces. We verify that in addition to atomic-scale variabilities, microstructural feature diversity can significantly impact effective transport properties. Across the ensemble of test microstructures, this often results in bimodal distributions of effective diffusivity that encompass two qualitatively distinct operating mechanisms, which we identify via flux analysis. An ML approach reveals that the most critical determining factors for effective diffusivity are the connectivity of bulk phases and their heterointerfaces. The role of ionic mobility at the heterointerfaces is also discussed. These insights highlight the combined importance of microstructure and interface engineering in tuning the transport properties of ionic species in composite materials. In conclusion, our framework can also be extended for understanding generic microstructure-property relationships in other complex multiphase materials.

25 ENERGY STORAGE↗