High entropy functional materials
Presented by NETL at World Congress on High Entropy Alloys (HEA 2019), 11/19
Miracle, Daniel B.↗
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Phosphate glass matrix composites incorporating trisilanol phenyl polyhedral oligomeric silsesquioxane prepared by viscous flow sintering method with enhanced benefits
The effect of mixing and sintering processes to prepare tin fluorophosphate glass (Pglass) matrix composites incorporating trisilanol phenyl polyhedral oligomeric silsesquioxane (TSP-POSS) was investigated by comparing manual and suspension mixing, one-step and stepwise sintering processes to explore the structure dynamics and physical properties in the composites as a function of the different process conditions used. Energy Dispersive X-ray analysis confirmed optimal homogeneous dispersion of the TSP-POSS molecules in the composites prepared by the suspension method. The observed increase of glass transition temperature and the reduction of non-bridging bonds in the composites are believed to be the reason for the effective dispersion of TSP-POSS molecules in the composites. The chemical reaction between the TSP-POSS and Pglass was strongly influenced by the mixing/dispersion and sintering processes investigated. 13 C cross polarized magic angle spinning (CP MAS) solid state nuclear magnetic resonance (NMR) spectroscopy confirmed the chemical stability of the TSP-POSS during the sintering process at elevated temperatures. In addition, a chemical reaction between the TSP-POSS and Pglass was evidenced by 29 Si CP MAS NMR analysis. Here, this study will provide a better fundamental understanding of the effective dispersion mechanism of the TSP-POSS molecules in the Pglass matrix that will facilitate tailoring the physicochemical properties of the composites with addition of various small concentrations of TSP-POSS for a number of applications where the pure Pglass is not applicable due to the intrinsic properties of the Pglass.
36 MATERIALS SCIENCE↗
Oxidation controlled phase composition of FeCo(Zr) nanoparticles in CaF{sub 2} matrix
Results of the study of oxidised (FeCoZr){sub x}(CaF{sub 2}){sub 100−x} films in a wide composition range (30 ≤ x ≤ 74 at.%) sintered at oxygen pressures P{sub O} = 4.3 and 9.8 mPa with X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), {sup 57}Fe Mössbauer spectroscopy (MS), and vibrating sample magnetometry (VSM) are reported. A “crystalline metallic core–amorphous oxide shell” structure of nanoparticles (NPs) in films oxidised at lower P{sub O} = 4.3 mPa is observed in TEM images. A combined use of XRD, MS and XAS techniques provides identification of NP phase composition evidencing α-FeCo(Zr) core of the variable content depending on x and a complex oxide shell including amorphous α-Fe{sup 3+}{sub 2}O{sub 3} together with Co{sup 2+}{sub 1−y}Fe{sup 2+}{sub y}O at low x (30–36 at.%). Full oxidation of NPs at higher P{sub O} = 9.8 mPa is indicated by TEM, XRD, MS and XAS patterns evidencing the formation of “crystalline Co{sup 2+}{sub 1−y}Fe{sup 2+}{sub y}O core–amorphous α-Fe{sup 3+}{sub 2}O{sub 3} shell” structure. Progressive oxidation of NPs with decreasing x at P{sub O} = 4.3 mPa as well as with P{sub O} increase is followed by variation of average centre shifts < δ > obtained from deconvoluted {sup 57}Fe Mössbauer spectra. Magnetometry measurements of films sintered at P{sub O} = 4.3 mPa reveal an effect of exchange bias confirming “ferromagnetic metallic core–antiferromagnetic oxide shell” structure of NPs. The results show that phase composition of oxide shells is governed both by concentration of oxygen available during synthesis and on the x. Schemes of progressive NP oxidation with identified phase composition as a function of P{sub O} and x values are proposed. - Highlights: • A selective oxidation of Fe in Fe–Co nanoparticles, NPs, is revealed. • Oxidation controlled composition of Fe–Co NPs in CaF{sub 2} matrix is determined. • “Metallic core–amorphous oxide shell”-like NPs are obtained at low oxygen pressure. • “Crystalline core–amorphous shell” oxide structures appear at high oxygen pressure. • A scheme of phase occurrence and structure of nanoparticles is proposed.
36 MATERIALS SCIENCE↗
Spallation-altered Accreted Compositions for X-Ray Bursts: Impact on Ignition Conditions and Burst Ashes
Model predictions of X-ray burst ashes and light curves depend on the composition of the material accreted from the companion star, in particular the abundance of CNO elements. It has previously been pointed out that spallation in the atmosphere of the accreting neutron star can destroy heavy elements efficiently. In this work we study this spallation using a realistic reaction network that follows the complete spallation cascade and takes into account not only destruction, but also production of elements by the spallation of heavier species. We find an increased survival probability of heavier elements compared to previous studies, resulting in significantly higher CNO abundances.We provide resulting compositions as a function of accretion rate, and explore their impact on 1D multi-zone X-ray burst models. Finally, we find significant changes in the composition of the burst ashes, which will affect the thermal and compositional structure of accreted neutron star crusts.
79 ASTRONOMY AND ASTROPHYSICS↗
Carbon dioxide adsorption on micro-mesoporous composite materials of ZSM-12/MCM-48 type: The role of the contents of zeolite and functionalized amine
Highlights: • Synthesis of the micro-mesoporous composite materials of ZSM-12/MCM-48 type. • Application of these adsorbents in the carbon dioxide adsorption. • Effects of the contents of zeolite and amino group in the material surface on the CO{sub 2} capture efficiency. - Abstract: In this study ZSM-12/MCM-48 adsorbents have been synthesized at three ZSM-12 content, and also were functionalizated with amine groups by grafting. All the adsorbents synthesized were evaluated for CO{sub 2} capture. The X-ray diffraction analysis of the ZSM-12/MCM-48 composite showed the main characteristic peaks of ZSM-12 and MCM-48, and after the functionalization, the structure of MCM-48 on the composite impregnated was affected due amine presence. For the composites without amine, the ZSM-12 content was the factor determining in the adsorption capacity of CO{sub 2} and for the composites with amine the amount of amine was that influenced in the adsorption capacity.
36 MATERIALS SCIENCE↗
Controlled High Filler Loading of Functionalized Al{sub 2}O{sub 3}-Filled Epoxy Composites for LED Thermal Management
Thermal management in light-emitting diode (LED) has been extensively researched recently. This study is intended to develop an effective thermally conductive epoxy composite as thermal interface material (TIM) for headlamp LEDs. Silane-functionalized aluminum oxide (Al{sub 2}O{sub 3}) powder of different average particle sizes (44 and 10 µm) was studied for its feasibility as filler at its maximum loading. A detailed comparison of three different methods of particle dispersions, hand-mix, speed-mix and calendaring process (3-roll mill), has been reported. The dispersion of Al{sub 2}O{sub 3} particles, the thermal conductivity and thermal degradation characteristics of the composites were investigated and explained in detail. At 75 wt.% filler loading, 10 and 44 µm Al{sub 2}O{sub 3} achieved composite thermal conductivities of 1.13 and 2.08 W/mK, respectively, which is approximately 528 and 1055% of enhancement with respect to neat epoxy. The package-level thermal performance of the LED employing the Al{sub 2}O{sub 3}-filled TIMs was carried out using thermal transient analysis. The experimental junction-to-ambient thermal resistances (R{sub thJ-A}) achieved were 6.65, 7.24, and 8.63 K/W for Al{sub 2}O{sub 3-44µm}, Al{sub 2}O{sub 3-10µm} and neat epoxy, respectively. The results revealed that the Al{sub 2}O{sub 3-44µm} fillers-filled composite performed better in both material-level and package-level thermal characteristics.
36 MATERIALS SCIENCE↗
Atomic layer deposition of Cd x Zn 1-x S films
Deposition of Cdsub>x Zn 1-x S has been demonstrated with atomic layer deposition (ALD) using diethylzinc (DEZn), dimethylcadmium (DMCd), and hydrogen sulfide as the precursors, and DFT calculations were performed to simulate the ALD process and the properties of the deposited films. The relative ratio of the pulses is varied for DMCd and DEZn to achieve different compositions over the spectrum from pure CdS to pure ZnS. Overall, the cadmium content in the films is higher than would be expected both as a function of pulse ratio and of temperature based on the growth rates of the binary films. At 150 °C pure ZnS shows almost pure cubic nature; however, the wurtzite content increases with the presence of cadmium until the film is approximately 10% wurtzite for pure CdS. Transmission electron microscopy (TEM) with high resolution confirms the coexistence of zincblende and wurtzite within grains due to the presence of stacking faults. The roughness of the films is a function of the composition, and the band gap and index of refraction can be finely tuned with composition.
33 ADVANCED PROPULSION SYSTEMS↗
Tribological Properties and Self-Repairing Functionality of Ti6Al4V-Multilayer Graphene-Ag Composites
Ti6Al4V alloy has broad application prospects in the aircraft industry. However, when it is served as frictional motion components, the poor friction and wear properties may greatly influence the reliability and working life of the entire mechanical system. Therefore, this paper mainly investigates the tribological performance and self-repairing functionality of Ti6Al4V-multilayer graphene (MLG)-Ag composites (TMAC) from 25 to 600 °C. The results show that TMAC obtains better tribological behavior in comparison with Ti6Al4V alloy (TC4), Ti6Al4V-MLG composites (TMC) and Ti6Al4V-Ag composites (TAC). It should be ascribed to the synergistic action of the reinforcement MLG and lubricant Ag, which are crushed and spread out by mechanical and thermal stress in the friction process, leading to the formation of a lubricating film on the wear scar. Along with the spreading of lubricating film, Ag and MLG can precipitate onto the microdefective areas, thus playing an important role in repairing the wear scar of TMAC.
36 MATERIALS SCIENCE↗
High Char Yield and Flowable Preceramic Resin Enabled with the Monomer Functionalized SiC Particle
Ceramic matrix composites (CMCs) are used in diverse high temperature applications; however, manufacturing CMCs is highly time consuming and costly. We address this challenge by introducing a methodology for fabricating CMCs using an innovative composite preceramic resin. This composite resin contains 40% mass loading of SiC particles, which are chemically functionalized with a resin monomer. The functionalization facilitates a homogenous dispersion of SiC particles within the resin matrix, resulting in high char yield (83.6%) and enhanced impregnation efficiency through reduced melt viscosity, ~10 Pa.s for relevant shear rates. This breakthrough represents a significant stride towards developing a more economically viable and efficient manufacturing process for CMCs.
14 SOLAR ENERGY↗
Mode I fracture toughness prediction for multiwalled-carbon-nanotube reinforced ceramics
Not Available
Nguyen, Ba Nghiep↗
Boson–fermion duality in a gravitational background
We study the 2+1 dimensional boson–fermion duality in the presence of background curvature and electromagnetic fields. The main players are, on the one hand, a massive complex |ϕ|{sup 4} scalar field coupled to a U(1) Maxwell–Chern–Simons gauge field at level 1, representing a relativistic composite boson with one unit of attached flux, and on the other hand, a massive Dirac fermion. We show that, in a curved background and at the level of the partition function, the relativistic composite boson, in the infinite coupling limit, is dual to a short-range interacting Dirac fermion. The coupling to the gravitational spin connection arises naturally from the spin factors of the Wilson loop in the Chern–Simons theory. A non-minimal coupling to the scalar curvature is included on the bosonic side in order to obtain agreement between partition functions. Although an explicit Lagrangian expression for the fermionic interactions is not obtained, their short-range nature constrains them to be irrelevant, which protects the duality in its strong interpretation as an exact mapping at the IR fixed point between a Wilson–Fisher–Chern–Simons complex scalar and a free Dirac fermion. We also show that, even away from the IR, keeping the |ϕ|{sup 4} term is of key importance as it provides the short-range bosonic interactions necessary to prevent intersections of worldlines in the path integral, thus forbidding unknotting of knots and ensuring preservation of the worldline topologies.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Approach to using 3D laser-induced breakdown spectroscopy (LIBS) data to explore the interaction of FLiNaK and FLiBe molten salts with nuclear-grade graphite
Nuclear graphite has historically been a key component of many nuclear reactor designs and has emerged as key to numerous advanced nuclear reactor design concepts. Molten salt reactors (MSRs) are one broad group of advanced reactor designs currently being pursued by industry for commercialization. Several MSR designs under consideration use graphitic materials that directly interface with a molten salt, whether it is a fuel salt, coolant salt, or both. Therefore, the interaction of graphite materials with molten salts must be understood. To gain this required understanding, a range of data is needed including porosity, strength, and composition as a function of different salt exposure parameters. In this study, a laser-induced breakdown spectroscopy (LIBS) measurement and data analysis methodology was developed to obtain spatially resolved elemental composition information for graphite samples exposed to a molten fluoride salt. Traditional univariate emission line analysis of atomic, ionic, and molecular optical emission signals was coupled via correlation analysis with spectral decomposition of the data using principal component analysis. Elemental depth profiling and elemental mapping were also performed to visualize salt–graphite interactions. LIBS was demonstrated to be useful for measuring key analytes such as fluorine and hydrogen, which are troublesome for other analysis techniques. Evidence for complex behavior was found, thereby demonstrating the usefulness of the developed approach for future systematic studies.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
3D printed porous silicone polymer composites using table salt as a sacrificial template
The incorporation of different functional fillers into the DIW composite resin can expand the functionality of 3D printed porous materials for different applications.
36 MATERIALS SCIENCE↗
DNA-functionalized scaffolds for drug capture applications
This disclosure is directed to structured compositions, including DNA-functionalized scaffolds, for drug capture, and methods and devices for sequestering chemotherapeutics from physiological fluids using the functionalized scaffolds.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Light-Stress Influences the Composition of the Murine Gut Microbiome, Memory Function, and Plasma Metabolome
The gut microbiome plays an important role in the mammalian host and when in proper balance helps protect health and prevent disease. Host environmental stress and its influence on the gut microbiome, health and disease is an emerging area of research. Exposures to unnatural light cycles are becoming increasingly common due to travel and shift work. However, much remains unknown about how these changes influence the microbiome and host health. This information is needed to understand and predict the relationship between the microbiome and host response to altered sleep cycles. In the present study, we exposed three cohorts of mice to different light cycle regimens for 12 consecutive weeks; including continuous light, continuous dark and a standard light dark regimen consisting of 12 hours light followed by 12 hours of dark. After exposure, motor and memory behavior, and the composition of the fecal microbiome and plasma metabolome were measured. Memory potential was significantly reduced in mice exposed to continuous light, whereas rotarod performance was minimally affected. The overall structure of the microbiome was relatively constant over time. However, Bacteroidales Rikenellaceae was relatively more abundant in mice exposed to continuous dark, while Bacteroidales S24-7 was relatively more abundant in mice exposed to continuous light. Several plasma metabolites, including glucose, tryptophan, pyruvate and several unidentified metabolites, were correlated to continuous dark and light exposure conditions. Specific metabolites were correlated to the abundances of specific microorganisms based on light exposure. This study provides the foundation for future studies into the mechanisms underlying the role of the gut microbiome on the murine host during light-dark stress.
59 BASIC BIOLOGICAL SCIENCES↗
First-principles analysis of the Al-rich corner of Al-Li-Cu phase diagram
The phase diagram of Al-Li-Cu system in the Al-rich region was determined by means of first-principles calculations and statistical mechanics. The mixing enthalpies of many configurations for different lattices in the whole Al-Li-Cu system were determined by density functional theory simulations to find the stable phases in the convex hull. They were fitted with a cluster expansion to calculate the free energy of the configurations with different compositions as a function of temperature in the Al-rich region (Al content > 40 at.%) by means of Monte Carlo simulations. It was found that the ground state phases in the Al-rich part of the Al-Li-Cu phase diagram were α-Al, θ' (Al 2 Cu), $δ$' (Al 3 Li), $δ$ (AlLi) and T 1 (Al 6 Cu 4 Li 3 ), while θ'' (Al 3 Cu), T 1' (Al 2 CuLi) and Al 3 Cu 2 Li were found on the lowest mixing enthalpy surfaces of their lattices and were metastable. α-Al, $δ$ and T 1 are stable phases in the whole temperature range while $δ$' becomes metastable at very low temperature and θ (Al 2 Cu) replaces θ' as the stable phase at approximately 550 K due to the vibrational entropic contribution. In addition, the phase diagram in the Al-rich region was built and it was shown in isothermal sections from 100 to 900 K. They were in good agreement with the limited experimental data in the literature and provided new information regarding the stability, solubility and stoichiometry of the different phases. This information is important to understand the precipitation mechanisms during high temperature aging.
36 MATERIALS SCIENCE↗
FY-13 FCRD Milestone M3FT-13OR0202311 Weldability of ORNL Accident Tolerant Fuel Cladding Model Alloys For Thin Walled Tubes
Ferritic FeCrAl-based alloys show increased oxidation resistance for accident tolerant applications as fuel cladding. This study focuses on investigating the weldability of three model FeCrAl alloys with varying alloy compositions using laser-welding techniques. A detailed study of the mechanical properties of bead-on-plate welds was used to determine the quality of welds as a function of alloy composition. Laser welding resulted in defect free welds devoid of cracking or inclusions. Initial results indicate a reduction in the yield strength of weldments compared to the base material due to distinct changes in the microstructure within the fusion zone. Although a loss of yield strength was observed, there was no significant difference in the magnitude of the tensile property changes with varying Cr or Al content. Also, there was no evidence of embrittlement; the material in the fusion zones demonstrated ductile behavior with high local ductility.
Field, Kevin G↗
Electronic transport in copper–graphene composites
In this work, we investigate electronic transport properties of copper–graphene (Cu–G) composites using a density-functional theory (DFT) framework. Conduction in composites is studied by varying the interfacial distance of copper/graphene/copper (Cu/G/Cu) interface models. Electronic conductivity of the models computed using the Kubo–Greenwood formula shows that the conductivity increases with decreasing Cu–G distance and saturates below a threshold Cu–G distance. The DFT-based Bader charge analysis indicates increasing charge transfer between Cu atoms at the interfacial layers and the graphene with decreasing Cu–G distance. The electronic density of states reveals increasing contributions from both copper and carbon atoms near the Fermi level with decreasing Cu–G interfacial distance. By computing the space-projected conductivity of the Cu/G/Cu models, we show that the graphene forms a bridge to the electronic conduction at small Cu–G distances, thereby enhancing the conductivity.
36 MATERIALS SCIENCE↗