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At least 145 records · Page 8

Exploring Fission–Fusion Synergies to Accelerate Compatibility Understanding

To address the significant commercial interest in fusion energy, it will be necessary to accelerate the compatibility research associated with liquid breeders including Li, eutectic Pb–Li and LiF-BeF 2 (FLiBe) molten salt. Particularly for FLiBe, compatibility understanding is limited especially for fusion relevant materials such as reduced activation ferritic-martensitic steels, SiC and V alloys. The historical knowledge associated with molten salt reactors (MSRs) and recent work to commercialize MSRs can benefit fusion research. Recent experimental and modeling work has improved understanding and this knowledge can be applied to fusion relevant materials. For liquid metals (LMs), the comparisons to Li and Pb–Li are less direct but nevertheless can help guide the pathway toward commercialization. For Pb–Li, Al-rich coatings have been shown to inhibit dissolution and potentially increase operating temperatures. For commercialization, the experience with sensors and on-line cleanup can help guide future developments. Thus, it is worth considering the potential for fission-related research with LMs and molten salts to help accelerate fusion research.

36 MATERIALS SCIENCE↗

Smartly Optimizing Crystallinity, Compatibility, and Morphology for Polymer Solar Cells by Small Molecule Acceptor with Unique 2D-EDOT Side Chain

A desired morphology is essential for achieving efficient polymer solar cells. Donors and acceptors with appropriate crystallization can lead to a suitable phase-separated morphology for effective photocurrent generation process. Inspired by the success of Y6 acceptors and the 2D side chain engineering on popular polymer donors and small molecule acceptors, the usage of unique 2D 3,4-ethylene dioxythiophene (EDOT) side chains on Y6 to regulate its crystallinity, compatibility, and thus the related blend morphology is explored. Here, in this study, two molecules of BTP-EDOT-4F and BTP-EDOT-4Cl with such unique 2D EDOT side chains are designed and synthesized. Due to the advantage of EDOT side chain, when these molecules are blended with PM6, the decent power conversion efficiencies (PCEs) of 16.78% and 15.87% are obtained. Furthermore, BTP-EDOT-4F is selected as the third component and added into PM6:L8-BO binary system to form ternary blends. The optimized crystallinity, compatibility, and morphology of such ternary blend are discovered in the presence of BTP-EDOT-4F, which enables efficient exciton dissociation and charge transport as well as decreased recombination, resulting in higher short circuit current density (J sc ) and fill factor. Finally, the outstanding PCE of 18.56% is achieved in ternary blends containing PM6, L8-BO, and BTP-EDOT-4F.

2D EDOT side chains↗

Investigation of Compatibility Between M-Cr-Al-X Thermal Spray Coatings and Third Generation γ-TiAl Alloys

In this work, the physical and chemical compatibility of cast Ti-Al-Nb-Cr-Zr and Ti-Al-Nb-Cr-Zr-B-La alloys was investigated with oxidation-resistant M-Cr-Al-X thermal spray coatings. Ti and Al are main alloy elements to form γ-TiAl and α{sub 2}-Ti{sub 3}Al phases. To obtain coatings, we used air plasma spray and high-velocity oxygen fuel equipment. Four commercially available M-Cr-Al-X powders, including Ta-containing, were used as starting materials. Our investigation of compatibility between M-Cr-Al-X thermal spray coatings and γ-TiAl alloys consists of isothermal annealing in air muffle furnace during 100 h at 920 °C, followed by samples investigation. Oxidation products formed at coatings surface were studied by XRD analysis with Rietveld refinement. Interdiffusion between coatings and alloys was studied by means of cross-sectional SEM with EDX analysis. Plots were made to show concentration of each main element at the end of experiments. Samples were subjected to dynamic mechanical thermal analysis in order to determine the effect of high-temperature exposure on complex elastic modulus. Finally, burner rig cycling test was performed to estimate the thermal shock resistance of M-Cr-Al-X coatings.

36 MATERIALS SCIENCE↗

Compatible meshfree discretization of surface PDEs

Meshfree discretization of surface partial differential equations is appealing, due to their ability to naturally adapt to deforming motion of the underlying manifold. In this work, we consider an existing scheme proposed by Liang et al. reinterpreted in the context of generalized moving least squares (GMLS), showing that existing numerical analysis from the GMLS literature applies to their scheme. With this interpretation, their approach may then be unified with recent work developing compatible meshfree discretizations for the div-grad problem in R d . Informally, this is analogous to an extension of collocated finite differences to staggered finite difference methods, but in the manifold setting and with unstructured nodal data. In this way, we obtain a compatible meshfree discretization of elliptic problems on manifolds which is naturally stable for problems with material interfaces, without the need to introduce numerical dissipation or local enrichment near the interface. As a result, we provide convergence studies illustrating the high-order convergence and stability of the approach for manufactured solutions and for an adaptation of the classical five-strip benchmark to a cylindrical manifold.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

An asymptotically compatible meshfree quadrature rule for nonlocal problems with applications to peridynamics

In this paper, we present a meshfree quadrature rule for compactly supported nonlocal integro-differential equations (IDEs) with radial kernels. We apply this rule to develop a meshfree discretization of a peridynamic solid mechanics model that requires no background mesh. Existing discretizations of peridynamic models have been shown to exhibit a lack of asymptotic compatibility to the corresponding linearly elastic local solution. By posing the quadrature rule as an equality constrained least squares problem, we obtain asymptotically compatible convergence by introducing polynomial reproduction constraints. Our approach naturally handles traction-free conditions, surface effects, and damage modeling for both static and dynamic problems. We demonstrate high-order convergence to the local theory by comparing to manufactured solutions and to cases with crack singularities for which an analytic solution is available. We verify the applicability of the approach to realistic problems by reproducing high-velocity impact results from the Kalthoff–Winkler experiments.

42 ENGINEERING↗

Compatibility of SiC with ODS FeCrAl in flowing Pb-Li at 600° - 700°C

To establish the maximum operating temperature for the dual coolant lead lithium (DCLL) blanket concept, thermal convection loop (TCL) experiments were conducted for 1000 h with a peak temperature of 700 °C to determine compatibility with commercial eutectic Pb~17at.%Li. Two TCLs were fabricated from alloy APMT (FeCrAlMo) and the baseline TCL experiment contained only APMT specimens. The second TCL experiment exposed more fusion relevant CVD SiC and ODS Fe-10Cr-6Al specimens in the hot and cold legs. In the second experiment, the mass losses were much larger for the ODS FeCrAl specimens and most of the CVD SiC specimens experienced a mass gain as SiC reacted to form an Fe- and Cr-rich carbide reaction product. Dissolved Fe and Cr reacted with the SiC and removing Fe and Cr from the liquid appeared to increase ODS FeCrAl dissolution. Such a dissimilar material interaction appears consistent with thermodynamic calculations. Significant attack at the top of the hot leg in both experiments suggests that the Pb-Li compatibility of FeCrAl alloys is inadequate at 700 °C in a flowing environment and the maximum PbLi temperature is < 675 °C.

36 MATERIALS SCIENCE↗

A compatible Lagrangian hydrodynamic scheme for multicomponent flows with mixing

We present a Lagrangian time integration scheme and compatible discretization for total energy conservation in multicomponent mixing simulations. Mixing behavior results from relative motion between species. Species velocities are determined by solving species momentum equations in a Lagrangian manner. Included in the species momentum equations are species artificial viscosity (since each species can undergo compression) and inter-species momentum exchange. Thermal energy for each species is also solved, including compression work and thermal dissipation caused by momentum exchange. The present procedure is applicable to mixing of an arbitrary number of species that may not be in pressure or temperature equilibrium. A traditional staggered stencil has been adopted to describe motion of each species. The computational mesh for the mixture is constructed in a Lagrangian manner using the mass-averaged mixture velocity. Species momentum equations are solved at the vertices of the mesh, and temporary species meshes are constructed and advanced in time using the resulting species velocities. Following the Lagrangian step, species quantities are advected (mapped) from the species meshes to the mixture mesh. Momentum exchange between species introduces work that must be included in an energy-conserving discretization scheme. This work has to be transformed to dissipation in order to effect a net change in species thermal energy. The dissipation between interacting species pairs is obtained by combining the momentum exchange work. The dissipation is then distributed to the species involved using a distribution factor based on species specific heats. The resulting compatible discretization scheme provides total energy conservation of the whole mixture. In addition, the numerical scheme includes conservative local energy exchange between species in mixture. Due to the relatively large species interaction coefficients, both the species momenta and energies are calculated implicitly. Sample calculations have yielded excellent results, including conservation of total energy in Lagrangian steps, symmetry preservation, and correct steady-state behavior.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

A multi-scale residual-based anti-hourglass control for compatible staggered Lagrangian hydrodynamics

Hourglassing is a well-known pathological numerical artifact affecting the robustness and accuracy of Lagrangian methods. There exist a large number of hourglass control/suppression strategies. In the community of the staggered compatible Lagrangian methods, the approach of sub-zonal pressure forces is among the most widely used. However, this approach is known to add numerical strength to the solution, which can cause potential problems in certain types of simulations, for instance in simulations of various instabilities. To avoid this complication, we have adapted the multi-scale residual-based stabilization typically used in the finite element approach for staggered compatible framework. In this study, we describe two discretizations of the new approach and demonstrate their properties and compare with the method of sub-zonal pressure forces on selected numerical problems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Evaluation of Pb-17Li compatibility of ODS Fe-12Cr-5Al alloys

The Dual Coolant Lead Lithium (DCLL: eutectic Pb–17Li and He) blanket concept requires improved Pb–17Li compatibility with ferritic steels in order to demonstrate acceptable performance in fusion reactors. As an initial step, static Pb-17at.%Li (Pb-17Li) capsule experiments were conducted on new oxide dispersion strengthened (ODS) FeCrAl alloys ((1) Y 2 O 3 (125Y), (2) Y 2 O 3 +ZrO 2 (125YZ), (3) Y 2 O 3 +HfO 2 (125YH), and (4) Y 2 O 3 +TiO 2 (125YT)) produced at ORNL via mechanical alloying (MA). Tests were conducted in static Pb–17Li for 1000 h at 700°C. Alloys showed promising compatibility with Pb–17Li with small mass change after testing for 125YZ, 125YH and 125YT, while the 125Y alloy experienced the highest mass loss associated with some oxide spallation and subsequent alloy dissolution. X-ray diffraction methods identified the surface reaction product as LiAlO 2 on all four alloys. A small decrease (~1 at.%) in Al content beneath the oxide scale was observed in all 4 ODS alloys, which extended through 60 μm beneath the oxide/metal interface. This indicates improvements in alloy dissolution by decreasing the amount of Al loss from the alloy. Scales formed on 125YZ, 125YH and 125YT were examined via scanning transmission electron microscopy (S/TEM) and revealed incorporation of Zr-, Hf-, and Ti-rich precipitates within the LiAlO2 product, respectively. This indicates an inward scale growth mechanism. Future work in flowing Pb–17Li is needed to further evaluate the effectiveness of this strategy in a test blanket module.

36 MATERIALS SCIENCE↗

Solid state cathode materials for secondary magnesium-ion batteries that are compatible with magnesium metal anodes in water-free electrolyte

With high elemental abundance, large volumetric capacity, and dendrite-free metal deposition, magnesium metal anodes offer promise in beyond-lithium-ion batteries. However, the increased charge density associated with the divalent magnesium-ion (Mg{sup 2+}), relative to lithium-ion (Li{sup +}) hinders the ion-insertion and extraction processes within many materials and structures known for lithium-ion cathodes. As a result, many recent investigations incorporate known amounts of water within the electrolyte to provide temporary solvation of the Mg{sup 2+}, improving diffusion kinetics. Unfortunately with the addition of water, compatibility with magnesium metal anodes disappears due to forming an ion-insulating passivating layer. In this short review, recent advances in solid state cathode materials for rechargeable magnesium-ion batteries are highlighted, with a focus on cathode materials that do not require water contaminated electrolyte solutions for ion insertion and extraction processes. - Graphical abstract: In this short review, we present candidate materials for reversible Mg-battery cathodes that are compatible with magnesium metal in water-free electrolytes. The data suggest that soft, polarizable anions are required for reversible cycling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Initiation and strain compatibility of connected extension twins in AZ31 magnesium alloy at high temperature

Uniaxial compression tests were carried out at 350 °C and a strain rate of 0.3 s{sup −1} on as-extruded AZ31 magnesium alloy samples. At a true strain of − 0.1, extension twin pairs in a grain and twin chains across adjacent grains were detected. The orientation of selected twins and their host grains were determined by electron backscattered diffraction (EBSD) techniques. The Schmid factors (SFs), accommodation strains and geometric compatibility factors (m{sup ′}) were calculated. Analysis of the data indicated that the formation of twin pair and twin chain was related to the SF and m{sup ′}. Regarding to twin chain across adjacent grains, accommodation strain was also involved. The selection of twin variants in twin chain was generally determined by m{sup ′}. When the twins required the operation of pyramidal slip or twinning in adjacent grain, the corresponding connected twins with a relative high m{sup ′} were selected in this adjacent grain. - Highlights: •The formation of paired twins is studied during high temperature deformation. •The initiation of twinning in twin pair and twin chain obeys the Schmid law. •The twin variants' selection in twin chain is related to the geometric compatibility factor. •The accommodation strain plays an important role on the formation of twin chain.

36 MATERIALS SCIENCE↗

Resistive switching phenomena of tungsten nitride thin films with excellent CMOS compatibility

Graphical abstract: - Highlights: • The resistive switching characteristics of WN{sub x} thin films. • Excellent CMOS compatibility WN{sub x} films as a resistive switching material. • Resistive switching mechanism revealed trap-controlled space charge limited conduction. • Good endurance and retention properties over 10{sup 5} cycles, and 10{sup 5} s, respectively - Abstract: We report the resistive switching (RS) characteristics of tungsten nitride (WN{sub x}) thin films with excellent complementary metal-oxide-semiconductor (CMOS) compatibility. A Ti/WN{sub x}/Pt memory cell clearly shows bipolar RS behaviors at a low voltage of approximately ±2.2 V. The dominant conduction mechanisms at low and high resistance states were verified by Ohmic behavior and trap-controlled space-charge-limited conduction, respectively. A conducting filament model by a redox reaction explains the RS behavior in WN{sub x} films. We also demonstrate the memory characteristics during pulse operation, including a high endurance over >10{sup 5} cycles and a long retention time of >10{sup 5} s.

36 MATERIALS SCIENCE↗

Low-cost spray-processed Ag{sub 1−x}Cu{sub x}InS{sub 2} nano-films: Structural and functional investigation within the Lattice Compatibility Theory framework

Highlights: • Cu{sub x}Ag{sub 1−x}InS{sub 2} with a minimal lattice mismatch between absorbers and buffers. • The lattice compatibility for understanding silver–copper kinetics. • Controlled and enhanced spray pyrolisis method as a low-cost synthesis protocol. - Abstract: This work deals with some structural and optical investigations about Cu{sub x}Ag{sub 1−x}InS{sub 2} alloys sprayed films and the beneficial effect of copper incorporation in AgInS{sub 2} ternary matrices. The main purpose of this work is to obtain the band gap energy E{sub g} as well as different lattice parameters. The studied properties led to reaching minimum of lattice mismatch between absorber and buffer layers within solar cell devices. As a principal and original finding, the lattice compatibility between both silver and copper indium disulfide structures has been proposed as a guide for understanding kinetics of these materials crystallization.

36 MATERIALS SCIENCE↗

NEXT GENERATION SOLVENT MATERIALS COMPATIBILITY WITH POLYMER COMPONENTS WITHIN MODULAR CAUSTIC-SIDE SOLVENT EXTRACTION UNIT

The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. The technical effort is collaboration between Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory. The first deployment target for the technology is within the Modular Caustic-Side Solvent Extraction Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with organic polymers used in the facility. This report provides the data from exposing these polymers to the Next Generation Solvent (NGS). The test was conducted over six months. An assessment of the dimensional stability of polymers present in MCU (i.e., PEEK, Grafoil{reg_sign}, Tefzel{reg_sign} and Isolast{reg_sign}) in the modified NGS (where the concentration of the guanidine suppressor and MaxCalix was varied systematically) showed that guanidine (LIX{reg_sign}79) selectively affected Tefzel{reg_sign} (by an increase in size and lowering its density). The copolymer structure of Tefzel{reg_sign} and possibly its porosity allows for the easier diffusion of guanidine. Tefzel{reg_sign} is used as the seat material in some of the valves at MCU. Long term exposure to guanidine, may make the valves hard to operate over time due to the seat material (Tefzel{reg_sign}) increasing in size. However, since the physical changes of Tefzel{reg_sign} in the improved solvent are comparable to the changes in the CSSX baseline solvent, no design changes are needed with respect to the Tefzel{reg_sign} seating material. PEEK, Grafoil{reg_sign} and Isolast{reg_sign} were not affected by guanidine and MaxCalix within six months of exposure. The initial rapid weight gain observed in every polymer is assigned to the finite and limited uptake of Isopar{reg_sign} L/Modifier by the polymers probably due to the polymers porosity and rough surfaces. Spectroscopic data on the organic liquid and the polymer surfaces showed no preferential adsorption of any component in the NGS to the polymers and no leachate was observed in the NGS from any of the polymers studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Corrosion Compatibility of Stainless Steels and Nickel in Pyrolysis Biomass-Derived Oil at Elevated Storage Temperatures

Corrosion compatibility of stainless steels and nickel (Ni200) was assessed in fast pyrolysis bio-oil produced from pyrolysis of high ash and high moisture forest residue biomass. Sample mass change, ICP-MS and post-exposure electron microscopy characterization was used to investigate the extent of corrosion. Among the tested samples, type 430F and type 316 stainless steels (SS430F and SS316) and Ni200 (~98.5% Ni) showed minimal mass changes (less than 2 mg∙cm−2) after the bio-oil exposures at 50 and 80 °C for up to 168 h. SS304 was also considered to be compatible in the bio-oil due to its relatively low mass change (1.6 mg∙cm−2 or lower). SS410 samples showed greater mass loss values even after exposures at a relatively low temperature of 35 °C. Fe/Cr values from ICP-MS data implied that Cr enrichment in stainless steels would result in a protective oxide layer associated with corrosion resistance against the bio-oil. Post exposure characterization showed continuous and uniform Cr distribution in the surface oxide layer of SS430F, which showed a minimal mass change, but no oxide layer on a SS430 sample, which exhibited a significant mass loss.

09 BIOMASS FUELS↗

Compatibility Assessment of Advanced Stainless Steels in Sodium

Type 316L stainless steel capsules containing commercially pure sodium and miniature tensile specimens of HT-UPS (austenitic, 14Cr-16Ni), NF-616 (ferritic/martensitic, 9Cr-2W-0.5Mo), or 316L (austenitic, 17Cr-10Ni-2Mo) stainless steel were exposed at 600 or 700 C for 100 and 400 h as a screening test for compatibility. Using weight change, tensile testing, and metallographic analysis, HT-UPS and 316L were found to be largely immune to changes resulting from sodium exposure, but NF-616 was found susceptible to substantial decarburization at 700 C. Subsequently, two thermal convection loops (TCLs) constructed of 316L and loaded with commercially pure sodium and miniature tensile specimens of HT-UPS and 316L were operated for 2000 h each one between 500 and 650 C, the other between 565 and 725 C at a flow rate of about 1.5 cm/s. Changes in specimen appearance, weight, and tensile properties were observed to be very minor in all cases, and there was no metallographic evidence of microstructure changes, composition gradients, or mass transfer resulting from prolonged exposure in a TCL. Thus, it appears that HT-UPS and 316L stainless steels are similarly compatible with commercially pure sodium under these exposure conditions.

36 MATERIALS SCIENCE↗

Material Compatibility with Isothermal Pb-Li

Eutectic Pb-Li is a leading candidate for current fusion blanket concepts as a coolant. However, there is very little data about the compatibility of most materials with Pb-Li above 500 C where the dissolution rate of many conventional alloys increases rapidly. Current work is beginning to assess Pb-Li compatibility from 500 to 800 C using isothermal capsule experiments. Aluminide coatings hold some promise in protecting conventional Fe-base alloys at 600-700 C. However, there is a significant initial Al loss that has not been clearly explained. Furthermore, the reaction product with coated materials is LiAlO{sub 2} rather than Al{sub 2}O{sub 3} at 600 and 700 C. Even when pre-oxidized to form {alpha}-Al{sub 2}O{sub 3}, an alumina layer on FeCrAl transformed to LiAlO{sub 2} at 700 and 800 C. At 500 C, the preformed oxide partially transformed from alumina and some Li was detected in the oxide layer.

36 MATERIALS SCIENCE↗

Synthesis of Biodegradable and Blood-Compatible Polyurethane Based on Poly(vinylpyrrolidone)

Three kinds of degradable and blood-compatible polyurethane (PU) were synthesized by coupling hydroxyl-terminated poly(vinylpyrrolidone) (PVP) with diisocyanate-terminated PU. The chemical structure and molecular weight of the synthesized copolymer were systematically characterized by nuclear magnetic resonance spectrum ({sup 1}HNMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The hydrophilicity and water absorption of the synthesized PU was increased by introducing PVP segment. To evaluate the hemocompatibility and degradability of the modified PU films, the extent of platelet adsorption, plasma recalcification time, hemolysis and degradation were measured. All results indicated that the blood compatibility and degradability of the PU films were improved significantly after introduction PVP segment into PU.

36 MATERIALS SCIENCE↗