Methane oxidation activity and nanoscale characterization of Pd/CeO2 catalysts prepared by dry milling Pd acetate and ceria
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99 GENERAL AND MISCELLANEOUS↗
SEARCH · Engineering Papers
Results for “Characterization”
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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Sol-gel Synthesis and Characterization of Gels with Compositions Relevant to Hydrated Glass Alteration Layers
During the processes associated with glass corrosion, porous alteration gel layers typically form upon exposure to aqueous conditions for extended time periods. The impacts of the alteration gel layer on glass durability have not been agreed upon in the glass science community. In particular, the formation mechanisms of the alteration gel layers are still largely unknown and require further investigation. However, alteration gel layers often require months to years to develop and are often too thin to adequately characterize. Meanwhile, silicate sol-gels are relatively easy to synthesize in bulk with custom compositions relevant to alteration gel layers. If glass alteration gel layers and synthetic sol-gel silicate gels demonstrate physical and chemical properties that are sufficiently similar, synthetic silicate gels could be used as analogues for glass alteration gel layers in future studies. In this study, sol-gels were made with custom compositions at various pH values to evaluate the effect of pH on gel structure and morphology. Several other variables were examined as well, such as composition, drying, and aging. Sol-gels were created by sequential additions of organometallic precursors in a single container. Synthesis procedural steps are provided in further detail within the text. Sol-gels were analyzed with several techniques including Small Angle X-ray Scattering (SAXS), gas adsorption, and He pynchometry to determine the effects of the variables on physical properties. Results show that sol-gels prepared at pH 3 consistently contained fewer primary particles with diameters larger than 72 Å and fewer pores with diameters larger than 300 Å compared to sol-gels synthesized at pH 7 and 9. Composition was shown to have no discernable effect on primary particle and pore sizes at any pH.
Reiser, Joelle TG↗
Energy dispersive X-ray diffraction (EDXRD) for operando materials characterization within batteries
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99 GENERAL AND MISCELLANEOUS↗
Recommendations for improving rigor and reproducibility in site specific characterization
Heterogeneous catalysis is driven by the interaction of reactant molecules and the catalyst surface. The locus of this interaction as well as the surrounding ensemble of atoms is referred to as the catalyst active site. Active site characterization attempts to distinguish active catalytic sites from inactive surface sites, to elucidate the structural and chemical nature of active sites, and to quantify active site concentration. Numerous techniques have been demonstrated to provide compositional and structural information about the active sites within a catalyst. However, each technique has its own limitations and experimental pitfalls that can lead to data misinterpretation or irreproducible results. Further, this work aims to provide an overview of the types of data that can be collected, to outline common experimental challenges and how to avoid them, and to assemble relevant references for the most used active site characterization techniques. More broadly, we aim to outline best practices for researchers to collect, interpret, and report active site characterization data in a way that provides the most benefit to the broader catalysis community. Increasing the rigor and reproducibility of active site characterization offers a strategy to better link properties with catalytic performance and to enable the community to develop consensus concerning these relationships.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Lab-Scale, Closed-Loop Experimental Characterization, Model Refinement, and Validation of a Hydrokinetic Energy-Harvesting Ocean Kite
This paper presents a study wherein we experimentally characterize the dynamics and control system of a lab-scale ocean kite, and then refine, validate, and extrapolate this model for use in a full-scale system. Ocean kite systems, which harvest tidal and ocean current resources through high-efficiency cross-current motion, enable energy extraction with an order of magnitude less material (and cost) than stationary systems with the same rated power output. However, an ocean kite represents a nascent technology that is characterized by relatively complex dynamics and requires sophisticated control algorithms. In order to characterize the dynamics and control of ocean kite systems rapidly, at a relatively low cost, the authors have developed a lab-scale, closed-loop prototyping environment for characterizing tethered systems, whereby 3D printed systems are tethered and flown in a water channel environment. While this system has been shown to be capable of yielding similar dynamic characteristics to some full-scale systems, there are also fundamental limitations to the geometric scales and flow speeds within the water channel environment, making many other real-world scenarios impossible to replicate from the standpoint of dynamic similarity. Here, to address these scenarios, we show how the lab-scale framework is used to refine and validate a scalable dynamic model of a tethered system, which can then be extrapolated to full-scale operation. In this work, we present an extensive case study of this model refinement, validation, and extrapolation on an ocean kite system intended for operation in the Gulf Stream or similar current environments.
42 ENGINEERING↗
Studies of CO2 hydrogenation over cobalt/ceria catalysts with in situ characterization: the effect of cobalt loading and metal-support interactions on the catalytic activity
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99 GENERAL AND MISCELLANEOUS↗
Experimental Characterization Test of a Grid-Forming Inverter for Microgrid Applications
Standardized experimental testing protocols for grid forming (GFM) inverters to ensure expected operation under both normal and contingency conditions do not exist. Such protocols increase the confidence of system owner/operators that an inverter deployed in a proposed system will engage in typical behaviors to ensure interoperability with other units and ancillary equipment (e.g. protection equipment). This paper presents systematic and comprehensive test protocols to evaluate the performance of GFM inverters under the following operational configurations: islanded operation, heterogeneous islanded operation (parallel with a synchronous generator), grid-connected operation, and transition operation. A commercial GFM inverter is used to verify the test protocols and to understand the inverter's performance and functionalities. In particular, required configuration and tuning of the inverter will be explained in the full paper to enrich the testing protocol.
black start↗
Comparing non-destructive 3D X-ray computed tomography with destructive optical microscopy for microstructural characterization of fiber reinforced composites
Due to their lightweight, relatively high stiffness properties, and formability into complex shapes, discontinuous fiber composites are advantageous for producing small and medium size components. Improved characterization techniques and post-processing methodologies are required for more reliable quantification of the microstructure and defect distributions in these materials, in order to employ model-based approaches to assess their structural integrity. This work compares a non-destructive X-ray approach with a destructive optical microscopy approach for characterizing the microstructural attributes, specifically the fiber volume fraction, porosity volume fraction, fiber orientation distribution, and fiber length distribution of discontinuous glass fibers in a polypropylene matrix. Additionally, a method for destructively determining the ambiguous components of the orientation tensor (related to the sign ambiguity of the out-of-plane angle in a destructive cross-sectional cut of a fiber) over a large surface area is included. It was found that fiber volume fraction and average fiber aspect ratio matched well, while fiber orientation and porosity detection had small but notable differences. The differences in the detection capabilities of each technique are quantified and discussed shedding light on the specific advantages and disadvantages of each approach, and enabling engineers to quantify uncertainty in their microstructural characterization measurements especially as they relate to model based structural integrity activities.
Non-destructive testing↗
Synthesis, structure, electronic characterization, and halogenation of gold(III) phlorin complexes
The metalation chemistry of the phlorin, which is a non-aromatic tetrapyrrole macrocycle containing a single sp 3 -hybridized meso-carbon has remained underdeveloped, as compared to that of more traditional tetrapyrroles such as porphyrins, corroles and phthalocyanines. There have been few prior efforts to prepare metallophlorins, and those that have been reported have relied on either reduction or nucleophilic attack of parent metalloporphyrins, rather than direct metalation of freebase phlorin constructs. In this work, an alternate synthetic approach for preparation of gold(III) phlorin complexes that involves the first direct metalation of two different freebase phlorin derivatives (3H(Phl tBu ) and 3H(Phl F )) with AuBr 3 to produce the stable and fully isolable gold(III) phlorin complexes Au(Phl tBu ) and Au(Phl F ) is reported. The first structural characterization of a metallophlorin bearing geminal dimethyl substituents at the sp 3 -hybridized meso-carbon via X-ray crystallography is also reported. In addition to the preparation of Au(Phl tBu ) and Au(Phl F ), the UV-vis absorption and redox properties of these two gold(III) phlorins in comparison to those of their freebase homologues is also detailed. Notably, the metallophlorins are characterized by panchromatic absorbance profiles and intense and broad bands that span the long-visible and into the near-IR regions, as well as two fully reversible oxidation and reduction waves as probed by cyclic voltammetry. Lastly, the chlorination of Au(Phl tBu ) using PhI(Cl 2 ) was probed and it was found that this regioslective reaction generates monochlorinated (Au(Phl tBu Cl)) and dichlorinated (Au(Phl tBu Cl 2 )) products, which were both structurally characterized by X-ray crystallography.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
The sensitive surface chemistry of Co-free, Ni-rich layered oxides: identifying experimental conditions that influence characterization results
Recent studies have suggested that Co-free, Ni-rich layered cathodes (e.g., doped LiNiO2) can provide promising battery performance for practical applications. However, these layered cathodes suffer from significant surface instability during various stages of the sample history, which generates inherent challenges for achieving stable battery performance and obtaining statistically representative characterization results. To reliably report the surface chemistry of these materials, delicate controls of stepwise sample preparation are required. In this study, we aim to reveal how the surface chemistry of LiNiO2 based materials changes with various environments, including human exhalation, sample storage, sample preparation, electrochemistry cycling, and surface doping. Our results demonstrate that the surface of these materials is highly reactive and prone to alter at various stages of sample handling and characterization. The sensitive surface could impact the interpretation of the surface chemical and structural information, including surface carbonate formation, transition metal reduction and dissolution, and surface reconstruction. Importantly, the heterogeneity of the surface degradation calls for a consolidation of nanoscale, high-resolution characterization, and ensemble-averaged methods in order to improve statistical representation. Furthermore, the doping chemistry can effectively mitigate the surface degradation and improve overall battery performance due to the enhanced surface oxygen retention. Our study highlights the necessity of strict measurements through complementary characterizations at multiple length scales to eliminate unintentional biased conclusions.
surface chemistry, Co-free Ni-rich cathodes, Istab↗
Systematic Characterization of Power Hardware-in-the-Loop Evaluation Platform Stability: Preprint
This paper presents a systematic approach to characterize the stability of a power-hardware-in-the-loop (PHIL) platform, an important step in PHIL tests. Many existing works focus the stability assessments on the PHIL interface algorithm; however, this work considers all software and hardware subsystems that form the closed loop of the PHIL experiment and develops a complete closed-loop stability assessment. This assessment is developed in the context of a common framework that can be readily applied to other PHIL platforms. This paper presents methods for characterizing key PHIL subsystems toward obtaining transfer functions to be used for analysis. The systematic stability assessment approach is demonstrated for a case study involving PHIL testing of a solar inverter and validated using experimental data. assessment. This assessment is developed in the context of a common framework that can be readily applied to other PHIL platforms. This paper presents methods for characterizing key PHIL subsystems toward obtaining transfer functions to be used for analysis. The systematic stability assessment approach is demonstrated for a case study involving PHIL testing of a solar inverter and validated using experimental data.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Materials Characterization, Prediction, and Control Project: Characterization of 316L Stainless Steel after Solid Phase Processing using Ultrasonic NDE Method
The Pacific Northwest National Laboratory undertook the Materials Characterization, Prediction, and Control Laboratory Directed Research and Development Project to advance understanding of nuclear material processing and enable multifold acceleration in the development and qualification of new material systems produced via advanced manufacturing methods, such as solid phase processing, for use in national security and advanced energy applications (Smith 2021). A motivation of the Materials Characterization, Prediction, and Control Project was to demonstrate ultrasonic testing as a nondestructive evaluation method to complement traditional destructive methods for characterizing material microstructure with emphasis on grain size determination using a method that may have future applications for real-time inline process monitoring. The objective of the work described in this report is to establish the process and an analysis method for measuring grain sizes of polycrystalline metals with ultrafine grains using ultrasonic shear wave backscattering, building on prior studies on coarser-grained material. The work involves five tasks: Measured ultrasonic backscattering experimentally for a series of 316L stainless steel specimens with various grain sizes made by friction stir processing. Calculated ultrasonic backscattering coefficients from experimental data based on a physical measurement model. Measured ground truth grain sizes of the specimens from electron backscatter diffraction grain boundary images using a generalization of the ASTM E112 (ASTM 2021) intercept method. Built a curve of ultrasonic backscattering coefficients versus the ground truth intercept-based grain sizes to determine the correlation between mean grain sizes and ultrasonic measurements. Demonstrated the ability of using the correlation curve to deduce grain sizes with measured ultrasonic backscattering coefficients for a few 316L stainless steel specimens whose grain sizes were unknown beforehand but were targeted to be an extrapolation to larger grain sizes than used to formulate the correlation curves. Experimental procedures and computational algorithms are developed and validated for these tasks. This work establishes an ultrasonic technique for characterizing material microstructure with ultrafine grains that are often resulted by solid-phase processing. The technique is nondestructive, and it has the potential to be used for real time inline process monitoring. This work successfully demonstrates the viability of an ultrasonic nondestructive evaluation method for microstructural characterization of material having ultrafine grain structure (as small as 1?mm) and produced by an advanced manufacturing method. This includes a demonstration of the method to extrapolate to other conditions. While not demonstrated here, the method is expected to be viable for in-line, or near-inline, process monitoring in advanced manufacturing applications with suitable consideration for access of instrumentation to the material being manufactured.
316 L Stainless Steel↗
Transmission electron microscopy characterization of the fuel-cladding chemical interactions in HT9 cladded U-10Zr fuel
Fuel cladding chemical interaction (FCCI) is a key phenomenon needs to be better understood to establish the design basis for U-10Zr metallic fuel performance. Characterizing the microstructure and chemical composition of FCCI at micron and sub-micron scale is critically important toward a more mechanistic understanding of FCCI phenomenon and its potential effects on cladding integrity and metallic fuel performance. This paper, by using transmission electron microscopy, investigated the FCCI region in HT9 cladded U-10Zr fuel irradiated to 5.7% FIMA burnup at a peak inner cladding temperature of 615 °C in Fast Flux Test Facility (FFTF). Four distinct layers are identified in the FCCI region. The migration of Fe into the fuel side leads to the formation of several U-Zr-Fe ternary phases, including ?-Fe0.5Zr0.32U0.18, e-Fe0.3Zr0.4U0.3, and ?-Fe0.06Zr0.23U0.71, mingled with UFe2, U6Fe, and U phase at various Fe penetration depth up to ~ 150 µm. On the cladding side, grain coarsening and significant lanthanides infiltration along grain boundaries are observed. Laves phase, (Fe,Cr)2(Mo,W), which typically does not exist in fresh HT9, is identified in a wide radial range in the cladding. The typical HT9 martensitic lath structure and pre-existing M23C6 precipitates disappear, partially or completely, depending on the radial distance from the fuel-cladding interface. Those microstructural and compositional changes could cause mechanical degradation in the HT9 cladding. The present characterization results will improve the understanding of FCCI phenomenon and facilitate the development of microstructure-informed FCCI modeling for metallic fuel.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Addressing Critical Problems in Materials Science Through Multiscale and Multimode Characterization (Project 1); Characterization and Optimization of Novel Triple-Conducting Oxide Materials for Energy Applications (Project 2) (CRADA Final Report)
PROJECT 1: Address critical problems in materials science and simultaneously advance the state-of-the-art in multiscale and multimode characterization using the combined advanced analytical capabilities and expertise of Colorado School of Mines (CSM) and the National Renewable Energy Laboratory (NREL). The primary effort of the Phase I of this CRADA is to establish the International Center for Multiscale Characterization using shared resources at both NREL and CSM. Phase II will focus on capability development and marketing, choosing candidate materials science issues in the areas of structure imaging, chemical composition mapping, and correlating properties and performance of materials for impact in energy-related, environmental and critical materials areas. The CRADA will be modified to include specific topics of concern in materials science to industry member partners. Advanced analytical capabilities and expertise at CSM and NREL will be used to advance materials understanding and performance through characterization of multiscale phenomena including structural imaging, chemical composition mapping, and other techniques correlating properties and performance of materials. PROJECT 2: As part of the International Center for Materials Characterization, work under Modification #1 will be led by Colorado School of Mines (CSM), working in collaboration with NREL staff to mentor and advise CSM postdoctoral researchers on set up of diffusion annealing experiments. The purpose of the modification is to provide for NREL staff to mentor and advise CSM postdoctoral researchers on set up of diffusion annealing experiments, including mentoring and advising the CSM-NREL team on proper Secondary Ion Mass Spectrometry (SIMS) data analysis as needed. SIMS measurements of 10-20 samples will be performed at NREL during the project duration.
08 HYDROGEN↗
High-resolution Hindcasts for U.S. Wave Energy Resource Characterization
The marine and hydrokinetic (MHK) industry is at an early stage of development and has the potential to play a significant role in diversifying the U.S. energy portfolio and reducing the U.S. carbon footprint. Wave energy is the largest among all the U.S. MHK energy resources, which include wave energy, ocean current, tidal-instream, ocean thermal energy conversion, and river-instream. Wave resource characterization is an essential step for regional wave energy assessments, Wave Energy Converter (WEC) project development, site selection and WEC design. The present paper provides an overview of a joint modelling effort by the Pacific Northwest National Laboratory and Sandia National Laboratories on high-resolution wave hindcasts to support the U.S. Department of Energy’s Water Power Technologies Office’s program of wave resource characterization, assessment and classifications in all US coastal regions. Topics covered include the modelling approach, model input requirements, model validation strategies, high performance computing resource requirements, model outputs and data management strategies. Examples of model setup and validation for different regions are provided along with application to development of classification systems, and analysis of regional wave climates. Lessons learned and technical challenges of the long-term, high-resolution regional wave hindcast are discussed.
Yang, Zhaoqing↗
Cryo-based Structural Characterization and Growth Model of Salt Film on Metal
Metal salt films play a critical role in high rate dissolution processes such as within an active pit. However, structural and compositional characterization of salt films is challenging owing to the dynamic nature of the dissolving interface. Here, the salt film formed on SS304 one-dimensional artificial pit surface was directly characterized using flash freezing and cryo-based focused ion beam/scanning electron microscopy. The salt film exhibits a porous structure. Ni is co-located with Fe in the salt film, indicating the formation of co-precipitated salt containing Fe2+ and Ni2+. Additionally, a salt film growth model is presented based on ion transport.
Salt film, Pitting corrosion, Cryogenic, Cryo-FIB/↗
Characterization of ferredoxins involved in electron transfer pathways for nitrogen fixation implicates differences in electronic structure in tuning 2[4Fe 4S] Fd activity
Ferredoxins (Fds) are small proteins which shuttle electrons to pathways like biological nitrogen fixation. Physical properties tune the reactivity of Fds with different pathways, but knowledge on how these properties can be manipulated to engineer new electron transfer pathways is lacking. Recently, we showed that an evolved strain of Rhodopseudomonas palustris uses a new electron transfer pathway for nitrogen fixation. This pathway involves a variant of the primary Fd of nitrogen fixation in R. palustris, Fer1, in which threonine at position 11 is substituted for isoleucine (Fer1 T11I ). To understand why this substitution in Fer1 enables more efficient electron transfer, we used in vivo and in vitro methods to characterize Fer1 and Fer1 T11I . Electrochemical characterization revealed both Fer1 and Fer1 T11I have similar redox transitions (–480 mV and – 550 mV), indicating the reduction potential was unaffected despite the proximity of T11 to an iron-sulfur (Fe—S) cluster of Fer1. Additionally, disruption of hydrogen bonding around an Fe—S cluster in Fer1 by substituting threonine with alanine (T11A) or valine (T11V) did not increase nitrogenase activity, indicating that disruption of hydrogen bonding does not explain the difference in activity observed for Fer1 T11I . Electron paramagnetic resonance spectroscopy studies revealed key differences in the electronic structure of Fer1 and Fer1 T11I , which indicate changes to the high spin states and/or spin-spin coupling between the Fe—S clusters of Fer1. Finally, our data implicates these electronic structure differences in facilitating electron flow and sets a foundation for further investigations to understand the connection between these properties and intermolecular electron transfer.
59 BASIC BIOLOGICAL SCIENCES↗