Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “In Situ Measurement”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Using real-time data analysis to conduct next-generation synchrotron fatigue studies

Next-generation experimental techniques, like high energy X-ray diffraction microscopy (HEDM), usher in new opportunities to collect the grain-scale data necessary for understanding the evolving processes that drive fatigue failure. In this study, we present a framework for monitoring the evolution of a deforming polycrystal, in real-time, by applying principal component analysis (PCA) to raw X-ray diffraction image data. We applied this framework to inform in-situ HEDM measurements of a cyclically loaded Inconel-718 superalloy. Further, we discovered correlations between PCA of the diffraction data and the physical processes in the polycrystal. Lastly, we discuss extending this framework in future HEDM fatigue studies.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Medium controlled aggregative growth as a key step in mesoporous silica nanoparticle formation

Near monodisperse mesoporous silica nanoparticles (MSN) represent a promising and rapidly developing type of mesoporous silica materials; however, the vast data on their synthesis remains unorganized and ill-understood. We systematically studied the formation of MSN under basic and neutral conditions using various temperatures, CTAB concentrations, hydrolyzing agents (triethanolamine, ammonia, phosphate buffers), and media with different colloidal stabilization properties (with ethanol as a cosolvent and monovalent salts). In the typical conditions for the preparation of stable MSN colloids, the particle size was controlled by colloidal stabilization by the medium (solvent type, ionic strength, and surfactant concentration) in agreement with the “aggregative growth” mechanism, rather than by solely the hydrolysis and condensation rates conventionally used for data interpretation in the classical nucleation theory. Medium properties (pH, ion types and concentration, polarity) also defined the efficiency of silica-surfactant cooperative self-assembly, which directly affected the porosity, mesopore size and pore wall thickness. Interestingly, this traditional silica-surfactant route showed a limited effect on the particle size, emphasizing the dominating role of colloidal stabilization in the studied reaction conditions. In situ pH measurements showed that every reaction medium has unique pH evolution profiles depending on the buffer capacity, hydrolysis and condensation rates. Reaction systems that fail to maintain the working pH can lead to non-porous products or undesired particle morphology and size distribution. The established particle formation mechanism allowed us to formulate comprehensive guidelines for preparing relatively concentrated colloids of near monodisperse (PDI 5–15%) mesoporous 30–700 nm silica spheres with variable porosity and mesopore size. Here, these findings will be particularly useful in designing new mesoporous silica-containing materials for biomedical applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Dry in-pile fracture test (DRIFT) for separate-effects validation of ceramic fuel fracture models

Fracture is an important component of nuclear fuel behavior, and significant efforts have been invested into developing fuel performance models that are capable of accurately representing fracture. Usable data on the process of fracture propagation in nuclear fuel under realistic service conditions are very limited. To address this need, a series of separate-effects experiments were developed and performed at Idaho National Laboratory's Transient Reactor Test (TREAT) facility. These experiments employ a heat sink to radially remove heat from the fuel in a manner that approximates the effect of coolant in an operating light-water reactor (LWR). The test holder for these experiments is known as the Dry In-pile Fracture Test (DRIFT). A series of experiments employing DRIFT and TREAT were performed to provide data on the extent and nature of fracture in fresh fuel at various points during a ramp to full power. Novel aspects of these experiments include the way they employ a heat sink to replicate steady-state LWR conditions, as well as the use of fiber optic sensors for in-reactor thermal instrumentation. Details on the development of this experiment, experimental conditions, and resulting data (including in situ thermal measurements and post-irradiation imaging of fracture) are provided in this work. LWR-equivalent powers ranging from 10 to 25 kW/m were tested using this apparatus. Cracking was visible at all power levels, with increasing cracking extent as the power level increased, although there was little difference in the cracking between the two highest-power tests, which had LWR-equivalent powers of 20 and 25 kW/m.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Gaining insight into lithium-ion battery degradation by a calorimetric approach

With the growing demand for lithium-ion batteries (LIBs) in transportation and renewable energy sectors, ensuring reliability and mitigating degradation are crucial challenges for their widespread deployment. Here this study investigates the relationship between thermal characteristics and degradation/reliability by developing an in-situ heat measurement methodology for LIBs operating under grid services. Using adiabatic mode-based calorimetry, we examine the thermal behavior of two commercial cells with different cathode chemistries (Ni-rich layered oxide and olivine) before and after two years of grid service (peak shaving) and demonstrate a strong correlation between thermal characteristics and electrochemical performance and its degradation. By further analyzing the heat sources separation (differentiating between irreversible and reversible heat), we disclose the underlying degradation mechanisms of LIBs. These findings emphasize the critical role of thermal characteristics in determining LIB reliability and deterioration, while the obtained heat data can aid in the development and calibration of LIB state-of-health models for grid applications.

25 ENERGY STORAGE↗
DOE OSTI2024

Identifying multiple synergistic factors on the susceptibility to stress relaxation cracking in variously heat-treated weldments

The 347H austenitic stainless steel has been widely used for pressure vessels and pipeline (PVP) applications due to its excellent creep and corrosion resistance, which fit ideally to the harsh conditions in petrochemical industries, fossil fuel or nuclear power plants, and modern energy storages. However, a failure mode has been commonly observed with cracks emerging at the heat affected zone (HAZ) of weldments during post-weld heat treatment (PWHT) or under intermediate to high temperature service conditions. This phenomenon is termed as Stress Relaxation Cracking (SRC) since the purpose of PWHT is to relieve the welding-induced residual stress fields, or as Stress Age Cracking (SAC) if failure happens during service. A leading literature explanation of this failure suggests that the residual stress relaxation and the precipitation dissolution and/or re-precipitation occur in the same temperature range, which can lead to locally high strains and thus to crack at the grain boundaries. Since in situ spatial measurements of residual stress fields, microstructural evolution, and failure processes are nearly infeasible, this work recourses to a micromechanical finite element framework that models the high temperature failure as the nucleation and growth of grain boundary cavities, whereas various parameters such as thermomechanical loading history and its evolution, the competition of grain-interior dislocation creep and grain-boundary diffusion in failure lifetime, and microstructural heterogeneities (such as the precipitate free zone near grain boundaries) can be quantitatively incorporated. It can be concluded from these microstructure-explicit simulations that an accurate knowledge of residual stress evolution and a carefully calibrated set of material constitutive parameters are the essential prerequisites for lifetime predictions. The understanding of individual governing factors also leads to a mechanistic interpretation of the observed SRC susceptibility C-curves. In conclusion, these results suggest that the criticality of residual stress evolution, but not the precipitation-induced local strains, be the leading factor for SRC.

347H stainless steel weldments↗
DOE OSTI2023

10 Be at iThemba LABS using a silicon nitride membrane stack as absorber for isobar suppression

10 Be is an important isotope for accelerator mass spectrometry (AMS) because of the demand for cosmogenic radionuclide dating methods in the earth science and paleo-sciences community. At the iThemba Laboratory for Accelerator Based Science (iThemba LABS) we implemented full suppression of the interfering isobar 10 B using a silicon nitride foil-stack, utilizing the 2+ charge state for high efficiency. We demonstrate the performance of this newly established AMS system using standards and test samples. Here we further present the results of an inter-comparison between iThemba LABS and the Center for Accelerator Mass Spectrometry/Lawrence Livermore National Laboratory, on AMS samples prepared from purified quartz at the University of Vermont. The results for 10 Be from the laboratories are in close agreement, fully consistent with cross-calibration between them. AMS results for 26 Al are in similarly good agreement, demonstrating the performance and accuracy of iThemba LABS for the most commonly measured in situ produced cosmogenic nuclides.

10-Be↗
DOE OSTI2025

First in operando transient grating spectroscopy measurements on tungsten during high flux plasma operation in PISCES-RF

This work details the construction and first in operando transient grating spectroscopy measurements conducted on PISCES-RF during plasma operation. A preliminary study on a tungsten sample with varied plasma species (Ar and D 2 ), ion flux (4 × 10 21 to 6 × 10 22 ion/m 2 /s), ion energy (5 to 80 eV), and surface temperature (20 to 200 °C) is presented. Prior to plasma exposure, the thermal diffusivity and surface acoustic wave (SAW) speed, (6.9 ± 0.2) × 10 −5 m 2 /s and (2.66 ± 0.02) km/s, were measured in situ with a thermal grating period of 12.5 μm. During Ar plasma exposure, these two quantities vary according to the sample surface temperature. At low flux and varied ion energy, D 2 plasma exposure also results in thermal diffusivity and SAW speed varying with surface temperature alone. At high flux, D 2 plasma exposure results in no convincing change to the thermal diffusivity, but the SAW speed is reduced. After returning to 20 °C, post plasma exposures, the thermal diffusivity and SAW speed almost recover to the initial value prior to exposure.

Surface acoustic wave SAW↗
DOE OSTI2023

Cooperative roles of water and metal-support interfaces in the selective hydrogenation of cinnamaldehyde over cobalt boride catalysts

Chemoselectivity in the hydrogenation of carbonyl over alkene bonds is valuable for producing industrial chemicals. In this study, we investigate the role of water in the selective hydrogenation of cinnamaldehyde on cobalt and cobalt boride catalysts by combining rate measurements, in situ characterization, and computational calculations. Ex situ and in situ spectroscopic analyses indicate that the boron species do not significantly modify the intrinsic electronic properties of cobalt. However, during thermal treatments, they exsolve from the bulk phase and become enriched on the surface, forming acidic species that enhance the activity and selectivity of carbonyl bond hydrogenation by three and two times, respectively. A small amount of water is able to promote hydrogenation. When titania, ceria, and zirconia are used as supports, metal-support interactions result in smaller particles that show a drop in selectivity toward the desirable unsaturated alcohol. Overall, the combination of the presence of boron species and strong metal-support interactions protects the catalysts from water attack, resulting in enhanced stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Hybrid-Lipid Bilayers Induce n -Alkyl-Chain Order in Reversed-Phase Chromatographic Surfaces, Impacting their Shape Selectivity for Aromatic Hydrocarbon Partitioning

Shape selectivity is important in reversed-phase liquid chromatographic separations, where stationary phases are capable of separating geometric isomers, thereby resolving solutes based on their three-dimensional structure or shape rather than other chemical differences. Numerous chromatographic studies have been carried out using n-alkyl-chain-modified columns to understand how molecular shape affects retention. For polycyclic aromatic hydrocarbons (PAHs), it was found that planar compounds were selectively retained over non-planar structures of comparable molecular weight on surfaces with longer n-alkyl chains, higher chain-density, or at lower temperatures, where selectivity likely arises with greater ordering of the n-alkyl chains. A limitation of these studies, however, is the small range of chain ordering that can be achieved and lack of a direct measure of the n-alkyl-chain order of the stationary phases. In this work, we employ a C 18 stationary phase modified with a monolayer of phospholipid as a means of significantly varying the n-alkyl chain order. These hybrid-supported lipid bilayers, which have previously been employed as membrane-like stationary phases for measuring lipophilicity, provide a unique approach to control n-alkyl chain ordering by varying the acyl chain length and degree of unsaturation of the phospholipid modifier. The degree of alkyl-chain order of the resulting modified surfaces is determined from the ratio of trans- versus gauche-conformers, measured in situ within individual porous particles by confocal Raman microscopy. This methodology was also used to assess the affinity of these surfaces for planar versus non-planar PAH molecules. The retention selectivity for the planar versus non-planar compounds, thus determined, was found to vary significantly and systematically with the degree of order of the acyl/alkyl chains in the hybrid-supported lipid bilayers. Furthermore, the investigation also demonstrates the utility of confocal Raman microscopy for interrogating the impact of solute partitioning on stationary-phase structure within porous chromatographic particles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Highly Oriented Organic Ferroelectric Films with Single-Crystal-Level Properties from Restrained Crystallization

Device applications often require thin film growth with quasi-two-dimensional morphology and crystallization which are not always compatible. In this work, we exploit the method of low-temperature deposition followed by restrained crystallization (LDRC) in the growth of crystalline organic molecular thin films, which tend to grow three-dimensionally with random orientations. We demonstrate that, for 2-methylbenzimidazole (MBI), a molecular ferroelectric that tends to crystalize in spherulites, the quasi-two-dimensional films can be grown using LDRC with highly oriented polar axes and single-crystal-level ferroelectric properties. The crystallization process was shown to occur during the post-deposition annealing process using the in situ electrical measurements. The limited diffusion, low nucleation density, and low activation energy was found critical for the formation of the plate-shaped quasi-two-dimensional films. These results mark an important step in elucidating the LDRC as an effective and general approach for fabricating films with balanced crystallinity and morphology which are critical for applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Probing Electronic and Structural Transformations during Thermal Reduction of the Promising Water Splitting Perovskite BaCe 0.25 Mn 0.75 O 3

Here, in this report, we investigate the thermal reduction of the octahedral perovskite BaCe 0.25 Mn 0.75 O 3 (BCM) using in situ electron energy loss spectroscopy (EELS) in an aberration-corrected transmission electron microscope (TEM). The 12R-polytype of BCM is known to demonstrate high solar thermochemical hydrogen production capacity. In situ EELS measurements show that Mn is the active redox cation in BCM, undergoing thermal reduction from Mn 4+ to Mn 3+ during heating to 700 °C inside the TEM under a high vacuum. The progressive reduction of Mn 4+ during oxygen vacancy (O v ) formation was monitored as a function of temperature. Additionally, atomic-resolution scanning transmission electron microscopy identified two different types of twin boundaries present in the oxidized and reduced form of 12R-BCM, respectively. These two types of twin boundaries were shown, via computational modeling, to modulate the site-specific O v formation energies in 12R-BCM. It is concluded that these types of atomic defects provide sites more energetically favorable for O v formation during thermal reduction.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Understanding How Ligand Functionalization Influences CO2 and N2 Adsorption in a Sodalite Metal–Organic Framework

In this work, a detailed study is conducted to understand how ligand substitution influences the CO2 and N2 adsorption properties of two highly crystalline sodalite metal–organic frameworks (MOFs) known as Cu–BTT (BTT–3 = 1,3,5-benzenetristetrazolate) and Cu–BTTri (BTTri–3 = 1,3,5-benzenetristriazolate). The enthalpy of adsorption and observed adsorption capacities at a given pressure are significantly lower for Cu–BTTri compared to its tetrazole counterpart, Cu–BTT. In situ X-ray and neutron diffraction, which allow visualization of the CO2 and N2 binding sites on the internal surface of Cu–BTTri, provide insights into understanding the subtle differences. As expected, slightly elongated distances between the open Cu2+ sites and surface-bound CO2 in Cu–BTTri can be explained by the fact that the triazolate ligand is a better electron donor than the tetrazolate. The more pronounced Jahn–Teller effect in Cu–BTTri leads to weaker guest binding. The results of the aforementioned structural analysis were complemented by the prediction of the binding energies at each CO2 and N2 adsorption site by density functional theory calculations. In addition, variable temperature in situ diffraction measurements shed light on the fine structural changes of the framework and CO2 occupancies at different adsorption sites as a function of temperature. Finally, simulated breakthrough curves obtained for both sodalite MOFs demonstrate the materials’ potential performance in dry postcombustion CO2 capture. The simulation, which considers both framework uptake capacity and selectivity, predicts better separation performance for Cu–BTT. The information obtained in this work highlights how ligand substitution can influence adsorption properties and hence provides further insights into the material optimization for important separations.

adsorption capacities↗
DOE OSTI2022

Anion Effects on the Interfacial Structure and Bulk Physical Properties in Choline-Based Hydrogen-Bonded Electrolytes

Electrolytes consisting of choline (Ch) salts with acetate (Ac) and oxalate (Ox) anions were studied in mixtures with ethylene glycol (EG), in comparison to chloride (Cl)- and bis(trifluorosulfonyl)imide (TFSI)-containing systems to understand the impact of anion size and charge density on the bulk electrolyte and interfacial properties. These represent hydrogen-bonded concentrated electrolytes where the Ch salts are the H-bond acceptors (HBAs) and EG is the H-bond donor (HBD) in 1:2 and 1:4 HBA:HBD ratios. Increased H-bonding in Ch 2 Ox with EG compacts the liquid compared to ChAc, consistent with the increased dissociation energies of the HBA:HBD clusters with Ox –2 calculated by density functional theory (DFT), thus leading to denser and more viscous liquids. Electrochemical impedance spectroscopy (EIS) and surface-enhanced Raman spectroscopy (SERS) were used to investigate interfacial charge density and the electrode surface species. Differential capacitance curves demonstrate weak dependence on potential except for ChAc:EG, where Ac – is found to adsorb on the Au surface, in particular at +0.055 V vs Ag quasi-reference while no specific adsorption was observed on glassy carbon (GC). In situ SERS measurement confirms the formation of a surface layer in the ChAc:EG systems resulting from a Au–acetate interaction. Despite the structural similarities, Ox –2 did not show specific binding or any dependence of capacitance on potential as a result of strongly solvating EG molecules via H-bonds. Furthermore, this study shows that the charge density of the HBAs impacts both bulk properties and the electrical double-layer formation in concentrated H-bonded electrolytes that is relevant to electrochemical kinetics and morphology in electrodeposition processes and energy storage applications.

25 ENERGY STORAGE↗
DOE OSTI2023

Site-Selective Atomic Layer Deposition on Rutile TiO 2 : Selective Hydration as a Route to Target Point Defects

Routes to area-and especially site-selective atomic layer deposition (ALD) remain an enticing challenge in precision surface science, despite the potentially game-changing capability for many energy applications. An unparalleled level of surface reaction control is required to direct ALD to select sites on the same nominal material, for example, targeted growth on distinct phases, facets, step-edges, and/or defects. However, as a sequential surface synthesis method, ALD is uniquely suited to these challenges, including the possibility of selective deposition at defective surface atom arrangements. Here, we computationally identify conditions for site-selective ALD through hydration of surface defects, including oxygen vacancies and titanium interstitials on low-index rutile TiO 2 facets. First-principles computation is used to predict, as a function of temperature, the hydroxylation of defects that are targeted by proton-exchange-mediated ALD processes. In situ ellipsometric measurements of ALD Al 2 O 3 nucleation on TiO 2 (110) single crystals prepared with and without abundant oxygen vacancies demonstrate striking contrast, corroborating computational predictions and revealing a mechanistically clear path to site-selective ALD.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Aligned Conjugated Polymer Nanofiber Networks in an Elastomer Matrix for High-Performance Printed Stretchable Electronics

Conjugated polymer films are promising in wearable X-ray detection. However, achieving optimal film microstructure possessing good electrical and detection performance under large deformation via scalable printing remains challenging. Herein, we report bar-coated high-performance stretchable films based on a conjugated polymer P(TDPP-Se) and elastomer SEBS blend by optimizing the solution-processing conditions. The moderate preaggregation in solution and prolonged growth dynamics from a solvent mixture with limited dissolving capacity is critical to forming aligned P(TDPP-Se) chains/crystalline nanofibers in the SEBS phase with enhanced π–π stacking for charge transport and stress dissipation. The film shows a large elongation at break of >400% and high mobilities of 5.29 cm 2 V –1 s –1 at 0% strain and 1.66 cm 2 V –1 s –1 over 500 stretch–release cycles at 50% strain, enabling good X-ray imaging with a high sensitivity of 1501.52 μC Gy air –1 cm –2 . Finally, our work provides a morphology control strategy toward high-performance conjugated polymer film-based stretchable electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Uncovering the Relationship between Diameter and Height of Electrodeposited Lithium Protrusions in a Rigid Electrolyte

A promising approach for enabling rechargeable batteries with significantly higher energy densities than current lithium-ion batteries is by deploying lithium-metal anodes. However, the growth of lithium protrusions during charging presents significant challenges. Since these protrusions are often branched and filamentous in conventional liquid electrolytes, this problem is referred to in the literature as the “dendrite problem”. While solid electrolytes have the potential to solve this problem, protrusions grow in all electrolytes when the current density exceeds a critical value. Fundamentally understanding the formation is necessary to develop a rational approach for increasing the critical current density, but it is challenging due to the complex interplay between electrochemical and material properties. The diameters and heights of protrusions on lithium-metal anodes stabilized by a rigid block copolymer electrolyte were measured in situ by synchrotron hard X-ray microtomography. The diameter of the shorting protrusions increased linearly with increasing electrolyte thickness. Further, a universal linear relationship between protrusion height and diameter of both shorting and non-shorting protrusions was observed. A model based on the concentrated solution theory was used to establish the electrochemical and mechanical sources for our observations. Here, the computational analysis indicates that elastic and plastic deformation of both the lithium metal and the polymer are important to describe protrusion growth. Both stress-induced current density effects due to the deformation of the electrolyte near the protrusion and plastic deformation of lithium metal combine to give the counterintuitive result: the fastest-growing protrusions have the largest diameter.

25 ENERGY STORAGE↗
DOE OSTI2022

Anodic Interfacial Evolution in Extremely Fast Charged Lithium-Ion Batteries

Interfacial reaction mechanisms at the anode/separator interface play a central role in the performance and safety of lithium-ion batteries during fast charging. We report a mechanistic study on the evolution and interactions of the aging mechanisms at the anode/separator interface in lithium cobalt oxide/graphite pouch cells charged with variable charging rates (1–6C) over 10 cycles. In situ electrochemical measurements, including voltage relaxation, Coulombic efficiency, and direct current internal resistance, indicated an incremental lithium loss until the C rates were ≤5C. A substantial capacity fade is observed in the first few cycles of fast charging, but the magnitude of capacity fade progressively diminishes with the number of cycles, indicating a suppression in the lithium deposition mechanism. Post-mortem film thickness, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) analyses were performed to elucidate the evolution of electrolyte decomposition, the solid–electrolyte interface (SEI), lithium plating, and film fracture mechanisms with C rate. XPS measurements confirmed an increasing lithium concentration in an SEI film with an increase in the C rate. SEM images showed a growth of dendritic lithium on the anode surface from 1C to 3C. Precrack formation leading to an interfacial film fracture was observed at higher C rates. Furthermore, a differential analysis of the discharge capacity indicated a possible two-phase delithiation from the anode and reduced cathodic lithiation due to lithium loss at high C rates.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Magnetohydrodynamic Control of Interfacial Degradation in Lithium-Ion Batteries for Fast Charging Applications

Interfacial anodic degradation in graphitic materials under fast charging conditions causes severe performance loss and safety hazard in lithium ion batteries. We present a novel method for minimizing the growth of these aging mechanism by application of an external magnetic field. Under magnetic field, paramagnetic lithium ions experience a magnetohydrodynamic force, which rotates the perpendicularly diffusing species and homogenizes the ionic transport. This phenomenon minimizes the overpotential hotspots at the anode/separator interface, consequently reducing SEI growth, lithium plating, and interfacial fracture. In situ electrochemical measurements indicate an improvement in capacity for lithium cobalt oxide/graphite pouch cell (20 mAh) charged from 1–5 C under an applied field of 1.8 kG, with a maximum capacity gain of 22% at 5C. Post-mortem FE-SEM and EDS mapping shows that samples charged with magnetic field have a reduced lithium deposition at 3C and a complete suppression of interfacial fracture at 5C. At 5C, a 24% reduction in the lithium content is observed by performing XPS on the anodic interfacial film. Finally, fast charging performance under variable magnetic field strengths indicate a saturation behavior in capacity at high fields (>2 kG), thereby limiting the field and consequent energy requirements to obtain maximum capacity gain under extreme conditions.

electromagnetism↗