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Articles 61 - 90 of 326
Full-Text Articles in Ceramic Materials
Zrc Particle Size Effect On The Mechanical Properties Of Spark Plasma Sintered 60–40 Vol% Zrc–Mo Cermets, Nathaniel Blatt, Jeremy Watts, Brian Taylor, Jhonathan Rosales, Gregory Hilmas
Zrc Particle Size Effect On The Mechanical Properties Of Spark Plasma Sintered 60–40 Vol% Zrc–Mo Cermets, Nathaniel Blatt, Jeremy Watts, Brian Taylor, Jhonathan Rosales, Gregory Hilmas
Materials Science and Engineering Faculty Research & Creative Works
Cermet's of 60 vol% ZrC and 40 vol% Mo with different starting ZrC particle sizes were spark plasma sintered to full density at 1950 °C. Elastic moduli, Vickers hardness and fracture toughness were measured at room temperature and flexural strength was measured up to 1600 °C. Young's modulus was 365 ± 5 GPa, shear modulus was 149 ± 2 GPa, Poisson's ratio was 0.22 ± 0.01, and no significant difference was observed for the moduli with respect to the starting ZrC particle size. Room temperature flexural strength was affected by the ZrC particle size, measured as ∼524 and ∼598 MPa …
Ultrafast Belite (Β-C2s) Production Using Biofuel-Based Combustion Synthesis, Shubham Agrawal, Sayee Srikarah Volaity, Oluwadamilare Charles Adesina, Bryan K. Aylas-Paredes, Taihao Han, Srinivas Kilambi, Aditya Kumar, Narayanan Neithalath
Ultrafast Belite (Β-C2s) Production Using Biofuel-Based Combustion Synthesis, Shubham Agrawal, Sayee Srikarah Volaity, Oluwadamilare Charles Adesina, Bryan K. Aylas-Paredes, Taihao Han, Srinivas Kilambi, Aditya Kumar, Narayanan Neithalath
Materials Science and Engineering Faculty Research & Creative Works
This study presents a novel low-temperature, combustion synthesis (CS) approach for the rapid production of belite-rich cements. CS leverages the exothermic heat released from the combustion of biofuels such as lignin and/or biomass, intermixed with pelletized limestone and quartz. At an imposed furnace temperature of ∼700°C (as opposed to 1200°C–1300°C required in a conventional kiln), the source materials are rapidly transformed to belite, resulting in energy, emissions, and economic benefits. This work explores the influence of various process parameters, viz., fuel types and contents, airflow rate, porosity, holding temperature, and holding time on the efficiency of CS-based belite synthesis. Through …
High-Frequency Gold Price Forecasting: Optimizing Multi-Layer Perceptron With Genetic Algorithm, Vrtagic Sabahudin, Fatih Dogan
High-Frequency Gold Price Forecasting: Optimizing Multi-Layer Perceptron With Genetic Algorithm, Vrtagic Sabahudin, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Accurately forecasting gold price actions is critical in financial markets due to gold's role as a safe-haven asset. This paper addresses the challenge of forecasting gold prices by applying a Genetic Algorithm (GA) with a Multi-Layer Perceptron (MLP) model. The research exploits historical financial data from various instruments, including gold futures, Bitcoin, and key currency pairs, to improve prediction accuracy. By optimizing the MLP's hyper parameters through GA, the model efficiently captures complex relationships in high-frequency data, achieving a remarkable R² score of 0.9993. This level of precision demonstrates the model's potential for providing actionable insights for traders and investors. …
Estimating The Possible Qpos Of M87* From The Parameters Of A Hairy Kerr Black Hole, Orhan Donmez, Fatih Dogan
Estimating The Possible Qpos Of M87* From The Parameters Of A Hairy Kerr Black Hole, Orhan Donmez, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
In this paper, we study the dynamics of the shock cone formed around a hairy Kerr black hole due to Bondi– Hoyle–Lyttleton (BHL) accretion and investigate the quasi-periodic oscillations (QPO) behaviors resulting from the black hole-cone interaction, aiming to predict the QPO frequencies that may occur around the M87∗ black hole. To achieve this, we use the hairy Kerr black hole parameters consistent with the observed shadow parameters of M87∗ as initial conditions in numerical simulations, revealing the structure of the resulting shock cone and QPOs in a strong gravitational field. Numerical calculations show that the deviation of …
Hafnium Oxide Coating To Improve The Oxidation Behavior Of Zirconium Diboride, Jan E. Förster, William G. Fahrenholtz, Gregory E. Hilmas, Ravisankar Naraparaju
Hafnium Oxide Coating To Improve The Oxidation Behavior Of Zirconium Diboride, Jan E. Förster, William G. Fahrenholtz, Gregory E. Hilmas, Ravisankar Naraparaju
Materials Science and Engineering Faculty Research & Creative Works
Hafnium dioxide (HfO2) coatings were successfully deposited on zirconium diboride (ZrB2) using reactive magnetron sputtering. After the oxidation at 1500°C or 1600°C, the mutual dissolution of HfO2 and thermally grown ZrO2 was observed which has resulted in the formation of a mixed oxide zone. As the enrichment of the mixed oxide zone by ZrO2 progresses, monoclinic/tetragonal phase transition temperature of ∼1790°C for nominally pure HfO2 moves towards ∼1500 °C. Finally, the inevitable phase transition from monoclinic to tetragonal structure results in the development of cracks, pores, and gaps within the mixed oxide …
Machine Learned Interatomic Potentials For Ternary Carbides Trained On The Aflow Database, Josiah Roberts, Biswas Rijal, Simon Divilov, Jon Paul Maria, William G. Fahrenholtz, Douglas E. Wolfe, Donald W. Brenner, Stefano Curtarolo, Eva Zurek
Machine Learned Interatomic Potentials For Ternary Carbides Trained On The Aflow Database, Josiah Roberts, Biswas Rijal, Simon Divilov, Jon Paul Maria, William G. Fahrenholtz, Douglas E. Wolfe, Donald W. Brenner, Stefano Curtarolo, Eva Zurek
Materials Science and Engineering Faculty Research & Creative Works
Large-density functional theory (DFT) databases are a treasure trove of energies, forces, and stresses that can be used to train machine-learned interatomic potentials for atomistic modeling. Herein, we employ structural relaxations from the AFLOW database to train moment tensor potentials (MTPs) for four carbide systems: CHfTa, CHfZr, CMoW, and CTaTi. The resulting MTPs are used to relax ~6300 random symmetric structures and are subsequently improved via active learning to generate robust potentials (RP) that can relax a wide variety of structures, and accurate potentials (AP) designed for the relaxation of low-energy systems. This protocol is shown to yield convex hulls …
Synthesis And Properties Of (Hf,Mo,Ti,W,Zr)B2–(Hf,Mo,Ti,W,Zr)C Dual Phase Ceramics, S. Filipović, S. M. Smith, G. Hilmas, W. Fahrenholtz, N. Obradović, S. Curtarolo
Synthesis And Properties Of (Hf,Mo,Ti,W,Zr)B2–(Hf,Mo,Ti,W,Zr)C Dual Phase Ceramics, S. Filipović, S. M. Smith, G. Hilmas, W. Fahrenholtz, N. Obradović, S. Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
Dense, dual phase (Hf,Mo,Ti,W,Zr)B2–(Hf,Mo,Ti,W,Zr)C ceramics were synthesized with varying contents of Mo and W. The final (Hf0.317Mo0.025Ti0.317W0.025Zr0.317)C–(Hf0.317Mo0.025Ti0.317W0.025Zr0.317)B2 was a nominally pure, dual phase ceramic, while compositions with higher amounts of Mo and W contained multiple phases. The final microstructures had submicron grains due to pinning effects. Vickers hardness values were up to 48.6 ± 2.2 GPa for an applied load of 0.49 N for the ceramic with optimized composition and densification. The solubility limits for Mo and …
Impact Of Tib2 Source On The Microstructure And Properties Of Tib2–Sic–B4c Ceramics, Steven M. Smith, Suzana Filipovic, William G. Fahrenholtz, Gregory E. Hilmas, Carlo Baldisserri, Laura Silvestroni
Impact Of Tib2 Source On The Microstructure And Properties Of Tib2–Sic–B4c Ceramics, Steven M. Smith, Suzana Filipovic, William G. Fahrenholtz, Gregory E. Hilmas, Carlo Baldisserri, Laura Silvestroni
Materials Science and Engineering Faculty Research & Creative Works
To date, the thermal and electrical properties of three-phase ceramics containing a boride phase, silicon carbide, and boron carbide have not been studied in detail. Further, the effect of the source of the boride powder has also not been investigated. This study produced three-phase ceramics containing titanium diboride, silicon carbide, and boron carbide using three different TiB2 sources: commercial powder, TiB2 synthesized by boro/carbothermal reduction, or (Ti,Cr)B2 synthesized by boro/carbothermal reduction to address the effect of the TiB2 source. Ceramics containing synthesized TiB2 or (Ti,Cr)B2 reached >99% relative density, while the ceramic produced from …
Response Of ¹¹B Enriched Zrb2 Ultra-High Temperature Ceramic To Neutron Irradiation At Elevated Temperatures, Yan Ru Lin, Takaaki Koyanagi, David J. Sprouster, Christian M. Petrie, William Fahrenholtz, Greg Hilmas, Yutai Katoh
Response Of ¹¹B Enriched Zrb2 Ultra-High Temperature Ceramic To Neutron Irradiation At Elevated Temperatures, Yan Ru Lin, Takaaki Koyanagi, David J. Sprouster, Christian M. Petrie, William Fahrenholtz, Greg Hilmas, Yutai Katoh
Materials Science and Engineering Faculty Research & Creative Works
ZrB2, an ultra-high temperature ceramic (UHTC) is being considered for use in fusion reactor first-wall structures, yet its response to irradiation remains poorly understood. This study employed scanning/transmission electron microscopy (S/TEM), synchrotron X-ray diffraction (XRD), finite element calculations, and thermal property measurements to thoroughly investigate the neutron-irradiation effects on 11B-enriched ZrB2. Neutron irradiations were conducted at 220 °C and 620 °C, with a neutron fluence of 2.2 x 1025 neutron/m2 (energy > 0.1 MeV), resulting in 3.9 dpa and 4200 appm He. The study revealed the unusual prevalence of prism loops and a > c anisotropic lattice …
Hardness Of Single Phase High Entropy Carbide Ceramics With Different Compositions, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz, Jeremy Lee Watts, Caillin J. Ryan, Chris M. Desalle, Douglas E. Wolfe, Stefano Curtarolo
Hardness Of Single Phase High Entropy Carbide Ceramics With Different Compositions, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz, Jeremy Lee Watts, Caillin J. Ryan, Chris M. Desalle, Douglas E. Wolfe, Stefano Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
Five High Entropy Carbide Ceramics, (Hf0.2,Nb0.2,Ta0.2,Ti0.2,Zr0.2)C, (Cr0.2,Hf0.2,Ta0.2,Ti0.2,Zr0.2)C, (Hf0.2,Mo0.2,Ta0.2,Ti0.2,Zr0.2)C, (Hf0.2,Ta0.2,Ti0.2,W0.2,Zr0.2)C, and (Hf0.2,Mo0.2,Ti0.2,W0.2,Zr0.2)C, Were Synthesized by Carbothermal Reduction of Oxides and Direct Current Sintering. the Five High Entropy Carbide Ceramics Were Determined to Be Nominally Phase-Pure with Relative Densities of More Than 98.9% and Mean Grain Sizes of Less Than 5 Μm. Average Vickers Hardness Values Ranged from 19.2 ± 0.4 GPa for (Hf0.2,Nb0.2,Ta0.2,Ti0.2,Zr0.2)C at a Load of 2 Kgf to 43.5 ± 0.4 GPa for (Hf0.2,Mo0.2,Ti0.2,W0.2,Zr0.2)C at a Load of 0.05 Kgf. Hardness Generally Increased with Increasing the Valence Electron Concentration and Strain as Measured by the Williamson-Hall Analysis. However, Neither …
Effect Of The Filler Morphology On The Crystallization Behavior And Dielectric Properties Of The Polyvinylidene Fluoride-Based Composite, Suzana Filipović, Nina Obradović, Cole Corlett, William G. Fahrenholtz, Martin Rosenschon, Ekkehard Füglein, Radovan Dojčilović, Dragana Tošić, Jovana Petrović, Antonije Đorđević, Branislav Vlahović, Vladimir B. Pavlović
Effect Of The Filler Morphology On The Crystallization Behavior And Dielectric Properties Of The Polyvinylidene Fluoride-Based Composite, Suzana Filipović, Nina Obradović, Cole Corlett, William G. Fahrenholtz, Martin Rosenschon, Ekkehard Füglein, Radovan Dojčilović, Dragana Tošić, Jovana Petrović, Antonije Đorđević, Branislav Vlahović, Vladimir B. Pavlović
Materials Science and Engineering Faculty Research & Creative Works
Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low dielectric permittivity, but increased dielectric permittivity can be achieved by the addition of the ceramic fillers with high dielectric constant. With the aim to enhance dielectric properties of the composite without loss of flexibility, 5 wt.% of BaTiO3-Fe2O3 powder was added into a polyvinylidene fluoride matrix. The powder was …
Dielectric Properties Of Polycrystalline And Single-Crystal Magnesium Oxide At High Temperatures, Alan Devoe, Hung Trinh, Fatih Dogan
Dielectric Properties Of Polycrystalline And Single-Crystal Magnesium Oxide At High Temperatures, Alan Devoe, Hung Trinh, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
The electrical properties of high-purity magnesium oxide (MgO) samples sintered between 1500 and 1650°C were investigated up to 800°C. Dielectric constant, loss tangent and electrical conductivity were measured between 25 and 800°C. Optimum electrical properties were obtained for the sample sintered at 1600°C. The impurities in polycrystalline and single crystal MgO were discussed to understand their effect on electrical properties and the role of grain boundaries. Higher dielectric losses of polycrystalline samples as compared to the single crystal MgO were attributed to the presence of grain boundaries. MgO could be a useful dielectric material for capacitor applications up to 600°C.
A Priori Procedure To Establish Spinodal Decomposition In Alloys, Simon Divilov, Hagen Eckert, Cormac Toher, Rico Friedrich, Adam C. Zettel, Donald W. Brenner, William G. Fahrenholtz, Douglas E. Wolfe, Eva Zurek, Jon Paul Maria, Nico Hotz, Xiomara Campilongo, Stefano Curtarolo
A Priori Procedure To Establish Spinodal Decomposition In Alloys, Simon Divilov, Hagen Eckert, Cormac Toher, Rico Friedrich, Adam C. Zettel, Donald W. Brenner, William G. Fahrenholtz, Douglas E. Wolfe, Eva Zurek, Jon Paul Maria, Nico Hotz, Xiomara Campilongo, Stefano Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
Spinodal decomposition can improve a number of essential properties in materials, especially hardness. Yet, the theoretical prediction of the onset of this phenomenon (e.g., temperature) and its microstructure (e.g., wavelength) often requires input parameters coming from costly and time-consuming experimental efforts, hindering rational materials optimization. Here, we present a procedure where such parameters are not derived from experiments. First, we calculate the spinodal temperature by modeling nucleation in the solid solution while approaching the spinode boundary. Then, we compute the spinodal wavelength self-consistently using a few reasonable approximations. Our results show remarkable agreement with experiments and, for NiRh, the calculated …
Dielectric Properties Of Polycrystalline And Single Crystal (100) Strontium Titanate From 4 To 295 K, Hung Trinh, Alan Devoe, Fatih Dogan
Dielectric Properties Of Polycrystalline And Single Crystal (100) Strontium Titanate From 4 To 295 K, Hung Trinh, Alan Devoe, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
The dielectric properties of single crystal and polycrystalline SrTiO3 (ST) were investigated from 295 to 4 K. Relative permittivity (εr) and loss tangent (tan(δ)) were measured systematically as a function of direct current (DC) voltage (0 V/cm to 800 V/cm), frequency (100 Hz to 1 MHz), and temperature (295 K to 4 K) for type (100) single crystal SrTiO3 (SC-ST) and for polycrystalline SrTiO3 (PC-ST). Calculated equivalent series resistance (ESR) data are also reported. Overall, the permittivity of ST showed a dependence on temperature, DC voltage, and frequency. Dependences on voltage and frequency were only observed at …
A Concept Of Producing Aluminum In-Situ On The Moon Through Molten Salt Electrolysis, Jacob N. Ortega, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daniel Stutts, Daoru Han
A Concept Of Producing Aluminum In-Situ On The Moon Through Molten Salt Electrolysis, Jacob N. Ortega, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daniel Stutts, Daoru Han
Materials Science and Engineering Faculty Research & Creative Works
This paper presents a concept of producing aluminum in-situ on the lunar surface, namely, the Lunar In-Situ Aluminum Production through Molten Salt Electrolysis (LISAP-MSE) method developed at Missouri University of Science and Technology. This paper aims to demonstrate the use of electro-deoxidation to reduce aluminum oxide (i.e., alumina) into aluminum and oxygen gas via electrolysis in a molten salt bath for the production of aluminum on the Moon. It is shown that with a steady supply of hydrogen chloride, this in-situ resource utilization (ISRU) method could supply several necessary materials consumed in the electro-deoxidation process except hydrogen chloride to produce …
Pressureless Sintering And Properties Of Additively Manufactured Zrb2–Sic, Marharyta Lakusta, Nicholas M. Timme, Jeremy L. Watts, William G. Fahrenholtz, Gregory E. Hilmas, David W. Lipke
Pressureless Sintering And Properties Of Additively Manufactured Zrb2–Sic, Marharyta Lakusta, Nicholas M. Timme, Jeremy L. Watts, William G. Fahrenholtz, Gregory E. Hilmas, David W. Lipke
Materials Science and Engineering Faculty Research & Creative Works
Densification behavior, grain growth kinetics, mechanical and thermal properties of pressurelessly sintered zirconium diboride–silicon carbide (ZrB2–SiC) fabricated by extrusion of high solids loading pastes have been studied. The effects of sintering temperature (1600–2300°C), heating rate during constant heating rate sintering (10–50°C/min), and time during isothermal sintering (3–24 h) on density and grain size were examined. The apparent activation energy for densification was determined to be 940 ± 90 kJ/mol, suggesting lattice diffusion as the dominant sintering mechanism. Grain growth of both ZrB2 and SiC followed a normal grain growth power law with grain growth exponent n = 2 indicating diffusion-controlled …
Kinetic Modeling Of Electrostatic Sieving For Lunar Regolith Beneficiation: Case Studies, Easton Ingram, Emmanuela Amen Eze, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Kinetic Modeling Of Electrostatic Sieving For Lunar Regolith Beneficiation: Case Studies, Easton Ingram, Emmanuela Amen Eze, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Materials Science and Engineering Faculty Research & Creative Works
A new kinetic particle modeling framework was developed to investigate electrostatic transport of lunar regolith particles with applications to the concept of electrostatic sieving. the new approach is based on kinetic particle dynamics and includes major modules of sampling the particle size distribution, solving electric fields, and tracking motion of charged dust grains. Case studies for a concept of electrostatic sieving were chosen to validate the new model. the simulation achieved similar yields reported in previous works, which served as validation of the model. the new model is computationally efficient and could serve as a design, analysis, and optimization tool.
Experimental Investigation Of A Viscoelastic Liner To Reduce Under Helmet Overpressures And Shock Wave Reflections, Cody J.H. Thomas, Fatih Dogan, Catherine E. Johnson
Experimental Investigation Of A Viscoelastic Liner To Reduce Under Helmet Overpressures And Shock Wave Reflections, Cody J.H. Thomas, Fatih Dogan, Catherine E. Johnson
Materials Science and Engineering Faculty Research & Creative Works
Introduction: Shock wave overpressure exposures can result in blast-induced traumatic brain injury (bTBI) in warfighters. Although combat helmets provide protection against blunt impacts, the protection against blast waves is limited due to the observed high overpressures occurring underneath the helmet. One route to enhance these helmets is by incorporating viscoelastic materials into the helmet designs, reducing pressures imposed on the head. This study aims to further investigate this mitigation technique against under-helmet overpressures by adding a viscoelastic liner to the inside of a combat helmet. Methods: The liner's effectiveness was evaluated by exposing it to free-field blasts of Composition C-4 …
Cf/Sic Ceramic Matrix Composites With Extraordinary Thermomechanical Properties Up To 2000 °C, Min Sung Park, Jian Gu, Heesoo Lee, Sea Hoon Lee, Lun Feng, William Fahrenholtz
Cf/Sic Ceramic Matrix Composites With Extraordinary Thermomechanical Properties Up To 2000 °C, Min Sung Park, Jian Gu, Heesoo Lee, Sea Hoon Lee, Lun Feng, William Fahrenholtz
Materials Science and Engineering Faculty Research & Creative Works
The thermomechanical properties of carbon fiber reinforced silicon carbide ceramic matrix composites (Cf/SiC CMCs) were studied up to 2000 °C using high temperature in situ flexural testing in argon. The CMC specimens were fabricated using an ultrahigh concentration (66 vol%) aqueous slurry containing nano-sized silicon carbide powder. The SiC powder compacts were obtained by drying the slurry and were densified using the precursor impregnation and pyrolysis (PIP) method with field assisted sintering technology/spark plasma sintering (FAST/SPS). The high relative density of the SiC green body (77.6%) enabled densification within 2.5 days using four PIP cycles. In contrast, conventional PIP processes …
Thermodynamic Analysis Of Metal Segregation In Dual Phase High Entropy Ceramics, Steven M. Smith, William G. Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo
Thermodynamic Analysis Of Metal Segregation In Dual Phase High Entropy Ceramics, Steven M. Smith, William G. Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
Equilibrium Gibbs' free energy calculations were used to determine metal segregation trends between boride and carbide solid solutions containing two metals that are relevant to dual phase high entropy ceramics. The model predicted that Ti had the strongest tendency to segregate to the boride phase followed by Zr, Nb, Mo, V, Hf, and Ta, which matches experimental results of measured compositions. The ratio of a metal in the carbide phase to the content of the same metal in the corresponding metal boride had a linear trend with the change in standard Gibbs' free energy of reaction for a metal carbide …
Spark Plasma Sintering Of Magnesium Titanate Ceramics, Suzana Filipović, Nina Obradović, William G. Fahrenholtz, Steven Smith, Miljana Mirković, Adriana Peleš Tadić, Jovana Petrović, Antonije Đorđević
Spark Plasma Sintering Of Magnesium Titanate Ceramics, Suzana Filipović, Nina Obradović, William G. Fahrenholtz, Steven Smith, Miljana Mirković, Adriana Peleš Tadić, Jovana Petrović, Antonije Đorđević
Materials Science and Engineering Faculty Research & Creative Works
Magnesium titanate ceramics were prepared by reactive spark plasma sintering (SPS) at 1200 °C for 5 min. Prior to sintering, MgO and TiO2 powders were mixed by high energy ball milling (HEBM) for 15, 30, or 60 min. The effect of milling time on phase composition was analyzed by X-ray diffraction (XRD) for milled powders and sintered specimens. The morphology of the sintered ceramics was investigated by scanning electron microscopy (SEM), while elemental distribution was determined by energy dispersive spectroscopy (EDS). The presence of the MgTi2O5 phase was detected in XRD and was confirmed by EDS analysis. Microcracking was …
A Super-Hard High Entropy Boride Containing Hf, Mo, Ti, V, And W, Suzana Filipovic, Nina Obradovic, Greg E. Hilmas, William G. Fahrenholtz, Donald W. Brenner, Jon Paul Maria, Douglas E. Wolfe, Eva Zurek, Xiomara Campilongo, Stefano Curtarolo
A Super-Hard High Entropy Boride Containing Hf, Mo, Ti, V, And W, Suzana Filipovic, Nina Obradovic, Greg E. Hilmas, William G. Fahrenholtz, Donald W. Brenner, Jon Paul Maria, Douglas E. Wolfe, Eva Zurek, Xiomara Campilongo, Stefano Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
Super-Hard (Hf,Mo,Ti,V,W)B2 Was Synthesized by Boro-Carbothermal Reduction and Densified by Spark Plasma Sintering. This Composition Was Produced for the First Time as a Single-Phase Ceramic in the Present Research. the Optimized Ceramic Had a Single Hexagonal AlB2-Type Crystalline Phase with a Grain Size of 3.8 µm and Homogeneous Distribution of the Constituent Metals. the Vickers Hardness Exhibited the Indentation Size Effect, Increasing from 27 GPa at a Load of 9.8 N to as High as 66 GPa at a Load of 0.49 N. This is the Highest Hardness Reported to Date for High Entropy Boride Ceramics.
Oxidation Of Additively Manufactured Zrb2–Sic In Air And In Co2 At 700–1000 °C, Marharyta Lakusta, Nicholas M. Timme, Abid H. Rafi, Jeremy Lee Watts, M. (Ming) C. (Chuan) Leu, Gregory E. Hilmas, William G. Fahrenholtz, David W. Lipke
Oxidation Of Additively Manufactured Zrb2–Sic In Air And In Co2 At 700–1000 °C, Marharyta Lakusta, Nicholas M. Timme, Abid H. Rafi, Jeremy Lee Watts, M. (Ming) C. (Chuan) Leu, Gregory E. Hilmas, William G. Fahrenholtz, David W. Lipke
Materials Science and Engineering Faculty Research & Creative Works
Oxidation behavior of additively manufactured zrb2–sic in air and in co2 is reported in the temperature range of 700–1000 °c. Observed scale morphologies in air and in co2 were similar, featuring an outer borosilicate layer and an inner porous zirconia layer containing partially oxidized silicon carbide particles and remnant borosilicate products. Oxide scale thicknesses and parabolic scaling constants in air were approximately twice those observed in co2 across all studied temperatures. Activation energies for oxidation of 140 ± 20 kj/mol in air and 110 ± 20 kj/mol in co2 were determined, indicating similar diffusion processes that appear to be rate-limiting. …
Thermal And Electrical Properties Of Single-Phase High Entropy Carbide Ceramics, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz, Jeremy Lee Watts, Stefano Curtarolo
Thermal And Electrical Properties Of Single-Phase High Entropy Carbide Ceramics, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz, Jeremy Lee Watts, Stefano Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
Thermal and Electrical Properties Were Investigated for Five Nominally Phase-Pure High Entropy Carbide Ceramics. the Compositions (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)C, (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C, (Hf0.2Mo0.2Ta0.2Ti0.2Zr0.2)C, (Hf0.2Ta0.2Ti0.2W0.2Zr0.2)C, and (Hf0.2Mo0.2Ti0.2W0.2Zr0.2)C Were Synthesized by Carbothermal Reduction of Oxides. the Thermal Diffusivity and Heat Capacity Were Measured from Room Temperature to 1800°C. the Room Temperature Thermal Conductivity Ranged from 5.1 W/mK for (Hf0.2Mo0.2Ti0.2W0.2Zr0.2)C to 9.0 W/mK for (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C. the Thermal Conductivity Increased over the Temperature Range with Maximum Conductivities of 19.6 W/mK Measured for (Hf0.2Mo0.2Ta0.2Ti0.2Zr0.2)C to 29.7 W/mK for (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C at 1800°C. the Electron Contribution to Thermal Conductivity Calculated from Measured Electrical Resistivity Varied from 41% to 52% of the …
Beneficiation Of Lunar Regolith Simulants Through Electrostatic Sieving And Magnetic Separation, Peter Bachle, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Beneficiation Of Lunar Regolith Simulants Through Electrostatic Sieving And Magnetic Separation, Peter Bachle, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Materials Science and Engineering Faculty Research & Creative Works
In the light of future development of lunar structures, in-situ feldspar beneficiation is imperative for metal extraction. This research incorporates the tandem use of electrostatic sieving and magnetic separation for collecting a specific size range and mineral composition from lunar soil that optimizes subsequent chemical processing. While earlier works focused on silt-sized particles, this work expands that range up to medium-grained sand with a greater variety of potential lunar regolith compositions. This work shows that a 2.5 kV, 7 Hz to 30Hz frequency, single-phase square wave can lift silt and fine sand for collection. This lifting is successful directly from …
Strength Comparison For Fully Dense Zirconium Diboride Ceramics Tested By Different Methods, Darko Kosanović, Suzana Filipović, Isaak Trajković, Nina Obradović, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz
Strength Comparison For Fully Dense Zirconium Diboride Ceramics Tested By Different Methods, Darko Kosanović, Suzana Filipović, Isaak Trajković, Nina Obradović, Paul M. Brune, Gregory E. Hilmas, William G. Fahrenholtz
Materials Science and Engineering Faculty Research & Creative Works
The strength of zirconium diboride ceramics was tested by three different methods, 3-point flexure, 4-point flexure, and compression. Nearly full-density ceramics were obtained by hot pressing commercial ZrB2 powder with the addition of.5 wt.% carbon as a sintering aid. The thermal properties and hardness were studied for ZrB2 milled with ZrB2 and WC media. Based on phase purity and higher thermal conductivity, ZrB2 ceramics prepared from powders milled with ZrB2 media were selected for mechanical property studies. The strength in 3-point flexure was 546 ± 55 MPa. The flexure strength was 476 ± 41 MPa …
Kinetic Modeling Of Electrostatic Sieving For Lunar Regolith Beneficiation: Case Studies, Easton Ingram, Emmanuela Amen Eze, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Kinetic Modeling Of Electrostatic Sieving For Lunar Regolith Beneficiation: Case Studies, Easton Ingram, Emmanuela Amen Eze, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Materials Science and Engineering Faculty Research & Creative Works
A new kinetic particle modeling framework was developed to investigate electrostatic transport of lunar regolith particles with applications to the concept of electrostatic sieving. The new approach is based on kinetic particle dynamics and includes major modules of sampling the particle size distribution, solving electric fields, and tracking motion of charged dust grains. Case studies for a concept of electrostatic sieving were chosen to validate the new model. The simulation achieved similar yields reported in previous works, which served as validation of the model. The new model is computationally efficient and could serve as a design, analysis, and optimization tool.
Synergistic Hardening In A Dual Phase High-Entropy (Hf,Nb,Ta,Ti,Zr)C–(Hf,Nb,Ta,Ti,Zr)B2 Ultra-High Temperature Ceramic, Rubia Hassan, William G. Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo
Synergistic Hardening In A Dual Phase High-Entropy (Hf,Nb,Ta,Ti,Zr)C–(Hf,Nb,Ta,Ti,Zr)B2 Ultra-High Temperature Ceramic, Rubia Hassan, William G. Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo
Materials Science and Engineering Faculty Research & Creative Works
A dual phase high-entropy (Hf,Nb,Ta,Ti,Zr)C–(Hf,Nb,Ta,Ti,Zr)B2 ultra-high temperature ceramic was synthesized using a single step boro-carbothermal reduction route. The synthesized powder was densified by spark plasma sintering at 2000°C, resulting in complete solid solution formation and a relative density of ≈99%. The dual phase ceramic was 43 vol% high-entropy carbide and 57 vol% high-entropy boride. The grain sizes were 0.85 ± 0.34 µm for the carbide and 0.87 ± 0.33 µm for the boride with minimal residual oxide (0.2 vol%) detected in the microstructure. The resulting composition had a higher microhardness than the individual boride and carbide ceramics across the range …
Development Of A Highly Loaded Zirconium Carbide Paste For Material Extrusion Additive Manufacturing, Clare Sabata, Austin J. Martin, Jeremy L. Watts, Gregory E. Hilmas
Development Of A Highly Loaded Zirconium Carbide Paste For Material Extrusion Additive Manufacturing, Clare Sabata, Austin J. Martin, Jeremy L. Watts, Gregory E. Hilmas
Materials Science and Engineering Faculty Research & Creative Works
A highly loaded, aqueous-based zirconium carbide (ZrC) paste was developed for ceramic on-demand extrusion (CODE). Commercial ZrC powder was ball milled to reduce the particle size to ∼1 μm. Paste composition was determined by rheological characterization and observation of printing behavior; the final paste consisted of 46–47 vol% ZrC, 43.5 vol% distilled water, 8.1 vol% dispersant, and 1.6 vol% binder. Rheological characterization of the paste showed a yield stress of ∼8 Pa and shear thinning behavior (ΔG′/Δσ* = −55). The paste was printed using a 610 μm nozzle; a test print showed shape fidelity using the developed paste. A pressureless …
Magnetic Separation Of Lunar Regolith Simulants With Applications To In Situ Resource Utilization On The Moon, Peter Bachle, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Magnetic Separation Of Lunar Regolith Simulants With Applications To In Situ Resource Utilization On The Moon, Peter Bachle, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han
Materials Science and Engineering Faculty Research & Creative Works
The development of in situ resource utilization (ISRU) for metal extraction is imperative as a steppingstone for habitation construction in lunar and non-terrestrial environments. Separation of minerals by chemical composition is important to optimize metal and oxygen liberation from lunar ore. to this effect, devices capable of separating aluminum bearing minerals from iron-bearing minerals from the lunar regolith simulants have been developed. Twenty-eight different simulants have been used in this study. a dual-belt separator was designed to reduce middlings. Para-magnetic minerals were reliably separated using a neodymium N52-magnet-separator system. Effective separation of aluminum-bearing minerals from iron-bearing minerals was greater than …