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At least 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Absorption of Nitrogen during Pulsed Wave L-PBF of 17-4 PH Steel

In the fabrication of 17-4 PH by laser powder bed fusion (L-PBF) the well-documented occurrence of large amounts of retained austenite can be attributed to an elevated concentration of nitrogen present in the material. While the effects of continuous wave (CW) laser processing on in-situ nitrogen absorption characteristics have been evaluated, power modulated pulsed wave (PW) laser processing effects have not. In this study the effects of PW L-PBF processing of 17-4 PH on nitrogen absorption, phase composition, and mechanical performance are explored using commercially available PW L-PBF equipment and compared to samples produced by CW L-PBF. PW L-PBF samples fabricated in cover gas conditions with varying amounts of nitrogen demonstrated reduced absorption levels compared to those produced by CW L-PBF with no effects on phase composition and minimal effects on mechanical performance.

17-4 PH↗
DOE OSTI2017

Solvent exchange in a metal–organic framework single crystal monitored by dynamic in situ X-ray diffraction

Understanding the processes by which porous solid-state materials adsorb and release guest molecules would represent a significant step towards developing rational design principles for functional porous materials. To elucidate the process of liquid exchange in these materials, dynamic in situ X-ray diffraction techniques have been developed which utilize liquid-phase chemical stimuli. Using these time-resolved diffraction techniques, the ethanol solvation process in a flexible metal–organic framework [Co(AIP)(bpy) 0.5 (H 2 O)]·2H 2 O was examined. The measurements provide important insight into the nature of the chemical transformation in this system including the presence of a previously unreported neat ethanol solvate structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Non-Destructive Monitoring of Charge-Discharge Cycles on Lithium Ion Batteries using 7 Li Stray-Field Imaging

Magnetic resonance imaging provides a noninvasive method for in situ monitoring of electrochemical processes involved in charge/discharge cycling of batteries. Determining how the electrochemical processes become irreversible, ultimately resulting in degraded battery performance, will aid in developing new battery materials and designing better batteries. Here we introduce the use of an alternative in situ diagnostic tool to monitor the electrochemical processes. Utilizing a very large field-gradient in the fringe field of a magnet, stray-field-imaging (STRAFI) technique significantly improves the image resolution. These STRAFI images enable the real time monitoring of the electrodes at a micron level. It is demonstrated by two prototype half-cells, graphite ∥Li and LiFePO 4 ∥ Li, that the high-resolution 7 Li STRAFI profiles allow one to visualize in situ Li-ions transfer between the electrodes during charge/discharge cyclings as well as the formation and changes of irreversible microstructures of the Li components, and particularly reveal a non-uniform Li-ion distribution in the graphite.

25 ENERGY STORAGE↗
DOE OSTI2014

In-situ and self-distributed: A new understanding on catalyzed thermal decomposition process of ammonium perchlorate over Nd{sub 2}O{sub 3}

Catalyzed thermal decomposition process of ammonium perchlorate (AP) over neodymium oxide (Nd{sub 2}O{sub 3}) was investigated. Catalytic performances of nanometer-sized Nd{sub 2}O{sub 3} and micrometer-sized Nd{sub 2}O{sub 3} were evaluated by differential scanning calorimetry (DSC). In contrast to universal concepts, catalysts in different sizes have nearly similar catalytic activities. Based on structural and morphological variation of the catalysts during the reaction, combined with mass spectrum analyses and studies of unmixed style, a new understanding of this catalytic process was proposed. We believed that the newly formed chloride neodymium oxide (NdOCl) was the real catalytic species in the overall thermal decomposition of AP over Nd{sub 2}O{sub 3}. Meanwhile, it was the “self-distributed” procedure which occurred within the reaction that also worked for the improvement of overall catalytic activities. This work is of great value in understanding the roles of micrometer-sized catalysts used in heterogeneous reactions, especially the solid–solid reactions which could generate a large quantity of gaseous species. - Graphical abstract: In-situ and self-distributed reaction process in thermal decomposition of AP catalyzed by Nd{sub 2}O{sub 3}. - Highlights: • Micro- and nano-Nd{sub 2}O{sub 3} for catalytic thermal decomposition of AP. • No essential differences on their catalytic performances. • Structural and morphological variation of catalysts digs out catalytic mechanism. • This catalytic process is “in-situ and self-distributed” one.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1994

Processing and Mechanical Properties of NiAl-Based In-Situ Composites

In-situ composites based on the NiAl-Cr eutectic system were successfully produced by containerless processing and evaluated. The NiAl-Cr alloys had a fibrous microstructure while the NiAl-(Cr,Mo) alloys containing 1 at. percent or more molybdenum exhibited a lamellar structure. The NiAl-28Cr-6Mo eutectic displays promising high temperature strength while still maintaining a reasonable room temperature fracture toughness when compared to other NiAl-based materials. The Laves phase NiAlTa was used to strengthen NiAl and very promising creep strengths were found for the directionally solidified NiAl-NiAlTa eutectic. The eutectic composition was found to be near NiAl-15.5Ta (at. percent) and well aligned microstructures were produced at this composition. An off-eutectic composition of NiAl-14.5Ta was also processed, consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of these two phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Polyphase in-situ composites were generated by directional solidification of ternary eutectics. The systems investigated were the Ni-Al-Ta-X (X=Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and both the eutectic composition and temperature were determined. Of these ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr,Al)NiTa-Cr eutectic was intermediate between those of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

Johnson, David Ray↗
DOE OSTI2021

Supply Chain Sustainability Analysis of Renewable Hydrocarbon Fuels via Indirect Liquefaction, Ex Situ Catalytic Fast Pyrolysis, Hydrothermal Liquefaction, Combined Algal Processing, and Biochemical Conversion: Update of the 2020 State-of-Technology Cases

The Department of Energy’s (DOE) Bioenergy Technologies Office (BETO) aims to develop and deploy technologies to transform renewable biomass resources into commercially viable, high-performance biofuels, bioproducts, and biopower through public and private partnerships (U.S. Department of Energy, 2016). BETO and its national laboratory teams conduct in-depth techno-economic assessments (TEA) of biomass feedstock supply and logistics and conversion technologies to produce biofuels. There are two general types of TEAs: A design case outlines a target case (future projection) for a particular biofuel pathway. It enables identification of data gaps and research and development needs and provides goals and benchmarks against which technology progress is assessed. A state of technology (SOT) analysis assesses progress within and across relevant technology areas based on actual results at current experimental scales relative to technical targets and cost goals from design cases, and includes technical, economic, and environmental criteria as available. In addition to developing a TEA for a pathway of interest, BETO also performs a supply chain sustainability analysis (SCSA). The SCSA takes the life-cycle analysis approach that BETO has been supporting for about 20 years. It enables BETO to identify energy consumption, environmental, and sustainability issues that may be associated with biofuel production. Approaches to mitigate these issues can then be developed. Additionally, the SCSA allows for comparison of energy and environmental impacts across biofuel pathways in BETO’s research and development portfolio. This technical report describes the SCSAs for the production of renewable hydrocarbon transportation fuels via a range of conversion technologies in the 2020 SOTs: (1) renewable high octane gasoline (HOG) via indirect liquefaction (IDL) of woody lignocellulosic biomass (note that the IDL pathway in this SCSA represents the syngas conversion design [Harris et al. 2021]); (2) renewable gasoline (RG) and diesel (RD) blendstocks via ex situ catalytic fast pyrolysis of woody lignocellulosic biomass [Abhijit et al. 2021]; (3) RD via hydrothermal liquefaction (HTL) of wet sludge from a wastewater treatment plant; (4) renewable hydrocarbon fuels via biochemical conversion of herbaceous lignocellulosic biomass (Davis et al. 2021; Lin et al. 2021); (5) renewable diesel via HTL of a blend of algae (Davis and Klein, 2021) and woody biomass (Hartley et al. 2020); and (6) renewable diesel via combined algae processing (CAP) (Wiatrowski and Davis, 2021). This technical report focuses on the environmental performance of these six biofuel production pathways in their 2020 SOT cases. The results of these renewable hydrocarbon fuel pathways in these SCSA analyses update those for the respective 2019 SOT cases (Cai et al. 2020). They also provide an opportunity to examine the impact of technology improvements in both biomass feedstock production and biofuel production that have been achieved in 2020 SOTs on the sustainability performance of these renewable transportation fuels. The SCSA results also reflect updates to Argonne National Laboratory’s Greenhouse gases, Regulated Emissions, and Energy use in Technologies (GREET®) model, which was released in October 2020 (Wang et al. 2020). These GREET updates include the production of natural gas, electricity, and petroleum-based fuels that can influence biofuels’ supply chain greenhouse gas (GHG) (CO 2 , CH 4 , and N 2 O) emissions, water consumption, and air pollutant emissions. GHG emissions, water consumption, and nitrogen oxides (NO x ) emissions are the main sustainability metrics assessed in this analysis. In this analysis, we define water consumption as the amount of water withdrawn from a freshwater source that is not returned (or returnable) to a freshwater source at the same level of quality. Life-cycle fossil energy consumption and net energy balance, which is the life-cycle fossil energy consumption deducted from the renewable biofuel energy produced, are also assessed.

09 BIOMASS FUELS↗
DOE OSTI2016

Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ε-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ε-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

The energetic basis for hydroxyapatite mineralization by amelogenin variants provides insights into the origin ofamelogenesis imperfecta

Small variations in the primary amino acid sequence of extracellular matrix proteins can have profound effects on the biomineralization of hard tissues. For example, a change in one amino acid within the amelogenin protein can lead to drastic changes in enamel phenotype, resulting in amelogenesis imperfecta, enamel that is defective and easily damaged. Despite the importance of these undesirable phenotypes, there is very little understanding of how single amino acid variation in amelogenins can lead to malformed enamel. Here, we aim to develop a thermodynamic understanding of how protein variants can affect steps of the biomineralization process. High-resolution, in situ atomic force microscopy (AFM) showed that altering one amino acid within the murine amelogenin sequence (natural variants T21 and P41T, and experimental variant P71T) resulted in an increase in the quantity of protein adsorbed onto hydroxyapatite (HAP) and the formation of multiple protein layers. Quantitative analysis of the equilibrium adsorbate amounts revealed that the protein variants had higher oligomer–oligomer binding energies. MMP20 enzyme degradation and HAP mineralization studies showed that the amino acid variants slowed the degradation of amelogenin by MMP20 and inhibited the growth and phase transformation of HAP. We propose that the protein variants cause malformed enamel because they bind excessively to HAP and disrupt the normal HAP growth and enzymatic degradation processes. The in situ methods applied to determine the energetics of molecular level processes are powerful tools toward understanding the mechanisms of biomineralization.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

In situ reaction mechanism studies on the Ti(NMe{sub 2}){sub 2}(O{sup i}Pr){sub 2}-D{sub 2}O and Ti(O{sup i}Pr){sub 3}[MeC(N{sup i}Pr){sub 2}]-D{sub 2}O atomic layer deposition processes

Reaction mechanisms in the Ti(NMe{sub 2}){sub 2}(O{sup i}Pr){sub 2}-D{sub 2}O and Ti(O{sup i}Pr){sub 3}[MeC(N{sup i}Pr){sub 2}] [also written Ti(O{sup i}Pr){sub 3}(N{sup i}Pr-Me-amd)]-D{sub 2}O atomic layer deposition processes were studied in situ with quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS) at 275 °C. For the Ti(NMe{sub 2}){sub 2}(O{sup i}Pr){sub 2}-D{sub 2}O process, both QCM and QMS results indicated adsorption of the Ti(NMe{sub 2}){sub 2}(O{sup i}Pr){sub 2} molecule through an exchange of at least one of its –NMe{sub 2} ligands with surface hydroxyl groups. Regarding the Ti(O{sup i}Pr){sub 3}(N{sup i}Pr-Me-amd)-D{sub 2}O process, a mismatch between the QCM and QMS results revealed more complex reactions: the decomposition of the [MeC(N{sup i}Pr){sub 2}] [also written (N{sup i}Pr-Me-amd)] ligand is suggested by the shape of the QCM data and the intensity of the QMS signals belonging to fragments of the [MeC(N{sup i}Pr){sub 2}] [also written (N{sup i}Pr-Me-amd)] ligand. A simple calculation model associating the growth rate per cycle of a crystalline film and the surface area taken by the ligands remaining after saturation was also used to support the decomposition of the [MeC(N{sup i}Pr){sub 2}] [also written (N{sup i}Pr-Me-amd)] ligand. The observed high growth rate is incompatible with the whole [MeC(N{sup i}Pr){sub 2}] (also written [N{sup i}Pr-Me-amd)] ligand remaining on the surface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Analysis of Localized Deformation Processes in Highly Irradiated Austenitic Stainless Steel through In Situ Techniques

This report describes new experimental results obtained during in situ mechanical tests with neutron-irradiated (10.7 dpa) austenitic 304L steel specimens. The in situ tensile tests inside a scanning electron microscope (SEM) were accompanied by modern high-resolution electron backscatter diffraction (HR-EBSD) analysis. The HR-EBSD approach allowed for investigating and quantifying internal stresses and dislocation structures in nondeformed and deformed steels, materials used in light water reactor internal components. The literature regarding the HR-EBSD analysis of metals and alloys is very limited, and practically no publications on the HR-EBSD analysis coupled with in situ tests are available. Experimental work, performed at Oak Ridge National Laboratory’s Low Activation Materials Development and Analysis facility, is detailed in this report. Section 1 briefly describes strain and stress localization processes and underlines their importance and role in irradiated materials, materials used in nuclear power plants. The section demonstrates that very limited quantitative data exist regarding localized stresses and strains in the irradiated materials at the meso-level (i.e., inside the grain, for a group of interacting grains, or for channel–grain boundary [GB] interaction) whereas local stresses at GBs are key contributors to the stress corrosion crack initiation.Section 2 documents the key methods used to conduct the experimental work: the SEM/EBSD system, miniature tensile frame, and irradiated material. Irradiated specimen manufacturing is described, as this option may be of special interest for other projects. Section 3 provides details of the HR-EBSD in situ tests (e.g., tensile curves, geometry, dimensions of regions of interest, load, and deformation steps). Section 4 discusses the results related to the evolution of geometrically necessary dislocations (GNDs) and their density, spatial, and statistical distributions.Section 5 focuses on the HR-EBSD analysis with respect to a channel–GB interaction. Two aspects are discussed in detail: mapping and analyzing the GND fields before and after loading, and the possibility of investigating local stresses and elastic strains at the channel–GB interaction. The present work results are beneficial for understanding strain and stress localization processes leading to crack initiation, for analyzing the material after long-term in-service life, and for developing predictive models. Section 6 summarizes the work performed and discusses future activities within this research direction.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2013

Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

36 MATERIALS SCIENCE↗
DOE OSTI2013

In situ characterization of nanoscale catalysts during anodic redox processes

Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anodecermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic).

08 HYDROGEN↗