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2020

Materials Science and Engineering

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Articles 1 - 30 of 181

Full-Text Articles in Engineering

Cooling Under Applied Stress Rejuvenates Amorphous Alloys And Enhances Their Ductility, Nikolai Priezjev Dec 2020

Cooling Under Applied Stress Rejuvenates Amorphous Alloys And Enhances Their Ductility, Nikolai Priezjev

Mechanical and Materials Engineering Faculty Publications

The effect of tensile stress applied during cooling of binary glasses on the potential energy states and mechanical properties is investigated using molecular dynamics simulations. We study the three-dimensional binary mixture that was first annealed near the glass transition temperature and then rapidly cooled under tension into the glass phase. It is found that at larger values of applied stress, the liquid glass former freezes under higher strain and its potential energy is enhanced. For a fixed cooling rate, the maximum tensile stress that can be applied during cooling is reduced upon increasing initial temperature above the glass transition point. …

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Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li Dec 2020

Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li

Mathematical Sciences Faculty Research

© 2020 The Author(s) In this paper, we investigate a system of governing equations for modeling wave propagation in graphene. Compared to our previous work (Yang et al., 2020), here we re-investigate the governing equations by eliminating two auxiliary unknowns from the original model. A totally new stability for the model is established for the first time. Since the finite element scheme proposed in Yang et al. (2020) is only first order in time, here we propose two new schemes with second order convergence in time for the simplified modeling equations. Discrete stabilities inheriting exactly the same form as the …

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Studies On Glass Fiber-Reinforced Poly(Ethylene-Grafted-Styrene)-Based Cation Exchange Membrane Composite, Di Huang, Zhichao Chen, Jiann-Yang Hwang Dec 2020

Studies On Glass Fiber-Reinforced Poly(Ethylene-Grafted-Styrene)-Based Cation Exchange Membrane Composite, Di Huang, Zhichao Chen, Jiann-Yang Hwang

Michigan Tech Publications

To improve interfacial adhesion between glass fiber (GF) and poly(ethylene-grafted-styrene)-based cation exchange membranes (CEM), GF was modified by four coupling agents: [3-(Methacryloxy)propyl] trimethoxy silane (3-MPS), 1,6-bis (trimethoxysilyl) hexane (1,6 bis), Poly(propylene-graft-maleic anhydride) (PP-g-MA) and Triethoxyvinylsilane (TES). The results indicated the addition of modified GF increased tensile strength, tensile modulus, storage modulus and interfacial adhesion of GF/CEM composite but degraded the strains. The composite with 3-MPS modified GF obtained superior mechanical properties and interfacial adhesion, whereas the modified effect of TES was inconspicuous. The addition of unmodified GF even had negative effects on GF/CEM mechanical properties. The field emission scanning electron …

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Optimization Of Electron Beam-Deposited Silver Nanoparticles On Zinc Oxide For Maximally Surface Enhanced Raman Spectroscopy, Andrew L. Cook, Christopher P. Haycook, Andrea K. Locke, Richard R. Mu, Todd D. Giorgio Dec 2020

Optimization Of Electron Beam-Deposited Silver Nanoparticles On Zinc Oxide For Maximally Surface Enhanced Raman Spectroscopy, Andrew L. Cook, Christopher P. Haycook, Andrea K. Locke, Richard R. Mu, Todd D. Giorgio

TIGER Institute Faculty Research

Surface enhanced Raman spectroscopy enables robust, rapid analysis on highly dilute samples. To be useful, the technique needs sensing substrates that will enhance intrinsically weak Raman signals of trace analytes. In particular, three-dimensional substrates such as zinc oxide nanowires decorated with electron-beam deposited silver nanoparticles are easily fabricated and serve the dual need of structural stability and detection sensitivity. However, little has been done to optimize electron beam-deposited silver nanoparticles for maximal surface enhancement in the unique dielectric environment of the zinc oxide substrate. Herein, fabrication and anneal parameters of electron beam-deposited silver nanoparticles were examined for the purpose of …

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A Computational Investigation Of The Interstitial Oxidation Thermodynamics Of A Mo-Nb-Ta-W High Entropy Alloy Beyond The Dilute Regime, Adib J. Samin Dec 2020

A Computational Investigation Of The Interstitial Oxidation Thermodynamics Of A Mo-Nb-Ta-W High Entropy Alloy Beyond The Dilute Regime, Adib J. Samin

Faculty Publications

High entropy alloys (HEAs) are promising candidates for high-temperature structural material applications. Oxidation is a major factor that must be accounted for when designing such materials and it is thus important to study the oxidation behavior of HEAs to enable the optimum design of next generation materials. In this study, the thermodynamic behavior of interstitial oxygen in a Mo-Nb-Ta-W high entropy alloy was explored beyond the dilute limit. This was accomplished by sampling configurations of the HEA and HEA-oxygen systems from an isothermal–isobaric ensemble using a series of first-principle-based Monte Carlo simulations. It was found that the interstitial oxygen had …

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Bio-Binder—Innovative Asphalt Technology, Amir Tabakovic Dec 2020

Bio-Binder—Innovative Asphalt Technology, Amir Tabakovic

Articles

The global road network spans 16.3 million km [1], of which 5 million km is in the EU. These road networks fulfil major economic and social goals by facilitating the movement of goods and people throughout the EU, and are therefore of the utmost importance to the economic and social life of the EU [2]. National governments invest heavily in their road networks, e.g., in 2014, EUR 53.33 billion was invested in the development and maintenance of the EU road network [3]. Each year, the world produces 1.6 trillion tonnes of asphalt [4], of which 218 million tonnes is produced …

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Ultrafast Spin-Currents And Charge Conversion At 3d-5d Interfaces Probed By Time-Domain Terahertz Spectroscopy, T. H. Dang, J. Hawecker, E. Rongione, G. Baez Flores, D. Q. To, J. C. Rojas-Sanchez, H. Nong, J. Mangeney, J. Tignon, F. Godel, S. Collin, P. Seneor, M. Bibes, A. Fert, M. Anane, J. M. George, L. Vila, M. Cosset-Cheneau, D. Dolfi, R. Lebrun, P. Bortolotti, Kirill Belashchenko, S. Dhillon, H. Jaffrès Dec 2020

Ultrafast Spin-Currents And Charge Conversion At 3d-5d Interfaces Probed By Time-Domain Terahertz Spectroscopy, T. H. Dang, J. Hawecker, E. Rongione, G. Baez Flores, D. Q. To, J. C. Rojas-Sanchez, H. Nong, J. Mangeney, J. Tignon, F. Godel, S. Collin, P. Seneor, M. Bibes, A. Fert, M. Anane, J. M. George, L. Vila, M. Cosset-Cheneau, D. Dolfi, R. Lebrun, P. Bortolotti, Kirill Belashchenko, S. Dhillon, H. Jaffrès

Kirill Belashchenko Publications

Spintronic structures are extensively investigated for their spin-orbit torque properties, required for magnetic commutation functionalities. Current progress in these materials is dependent on the interface engineering for the optimization of spin transmission. Here, we advance the analysis of ultrafast spin-charge conversion phenomena at ferromagnetic-Transition metal interfaces due to their inverse spin-Hall effect properties. In particular, the intrinsic inverse spin-Hall effect of Pt-based systems and extrinsic inverse spin-Hall effect of Au:W and Au:Ta in NiFe/Au:(W,Ta) bilayers are investigated. The spin-charge conversion is probed by complementary techniques-ultrafast THz time-domain spectroscopy in the dynamic regime for THz pulse emission and ferromagnetic resonance spin-pumping …

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Effects Of Ca Doping On Structural And Optical Properties Of Pzt Nanopowders, K. H. Omran, M. Mostafa, M. S. Abd El-Sadek, O. M. Hemeda, R. Ubic Dec 2020

Effects Of Ca Doping On Structural And Optical Properties Of Pzt Nanopowders, K. H. Omran, M. Mostafa, M. S. Abd El-Sadek, O. M. Hemeda, R. Ubic

Materials Science and Engineering Faculty Publications and Presentations

The influence of the addition of calcium ions (Ca2+) in the Pb(1-x)CaxZr0.52Ti0.48O3 system (PCZT) for x = 0.05, 0.10, 0.15, 0.20, and 0.25 on the structural and optical properties was systematically studied. The compositions were synthesized through a polymerized-complex approach based on the Pechini polymeric precursor route. The solubility limit of calcium ions within the PCZT lattice is in between x = 0.10 and x = 0.15, at which a CaTiO3 secondary phase is detected. The Goldschmidt tolerance factors, modified tolerance factors, and the effective vacancy sizes were …

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Soil-Cement Bricks Produced From Local Clay Brick Waste And Soft Sludge From Fiber Cement Production, Nuntaporn Kongkajun, Edward A. Laitila, Pitcharat Ineure, Wichit Prakaypan, Benya Cherdhirunkorn, Parinya Chakartnarodom Dec 2020

Soil-Cement Bricks Produced From Local Clay Brick Waste And Soft Sludge From Fiber Cement Production, Nuntaporn Kongkajun, Edward A. Laitila, Pitcharat Ineure, Wichit Prakaypan, Benya Cherdhirunkorn, Parinya Chakartnarodom

Michigan Tech Publications

Soil-cement bricks were produced using local clay brick waste (CBW) and soft sludge (SS) from fiber-cement industries, preserving raw resources by substituting with industrial wastes. The control formula to produce soil-cement bricks, is 15 wt% Portland cement, 15 wt% sand, and 70 wt% laterite. Clay brick waste was added with values from 10 to 50 % of laterite weight in the control formula. For SS, 5 and 10 % was used to replace the total weight of the dry mixture in the control formula. The samples were shaped by using a manual brick making machine. The results showed that the …

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Properties And Performance Of The Basalt-Fiber Reinforced Texture Roof Tiles, Parinya Chakartnarodom, Wichit Prakaypan, Pitcharat Ineure, Nutthita Chuankrerkkul, Edward A. Laitila, Nuntaporn Kongkajun Dec 2020

Properties And Performance Of The Basalt-Fiber Reinforced Texture Roof Tiles, Parinya Chakartnarodom, Wichit Prakaypan, Pitcharat Ineure, Nutthita Chuankrerkkul, Edward A. Laitila, Nuntaporn Kongkajun

Michigan Tech Publications

The mechanical and the physical properties, and the performance of texture roof tiles reinforced with the basalt fibers were observed. The samples of the basalt-fiber reinforced texture roof tiles were produced on the industrial scale by using filter pressing method. After forming, the as-molded samples were air cured and characterized based on ASTM C1185 standard for their mechanical properties and physical properties. In addition, the roof-tile installation test was also performed. The results showed that the samples of the basalt-fiber reinforced texture roof tile (BFRT) could be produced on the industrial scale by using the common setting of the forming …

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Toward Understanding Underlying Mechanisms Of Drag Reduction In Turbulent Flow Control, Alex Rogge Dec 2020

Toward Understanding Underlying Mechanisms Of Drag Reduction In Turbulent Flow Control, Alex Rogge

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The underlying mechanisms of three different flow-control strategies on drag reduction in a turbulent channel flow are investigated by direct numerical simulations. These strategies include the addition of a small concentration of long-chain polymers into a fluid, the incorporation of slip surfaces, and the application of an external body force. While it has been believed that such methods lead to a skin-friction reduction by controlling near-wall flow structures, the underlying mechanisms at play are still not as clear. In this study, a temporal analysis is employed to elucidate underlying drag-reduction mechanisms among these methods. The analysis is based on the …

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Fluid Modeling And Analysis Of A Mash Tl-6 Vehicle Model, Elisa Vasquez Dec 2020

Fluid Modeling And Analysis Of A Mash Tl-6 Vehicle Model, Elisa Vasquez

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The objective of this research project was to replicate the dynamic behavior of a truck-tank trailer combination vehicle using representative dimensions, properties, and inertias of the trailer/fluid ballast combination. A literature review was completed describing techniques for modeling fluids and fluid-container interactions using finite element analysis. Various fluid modeling techniques were identified, and parameters associated with those models were archived. Next, researchers utilized the tank geometry of the elliptical straight-frame 5949 trailer produced by LBT Inc. to generate a finite element mesh using finite element analysis preprocessors HyperMesh and LS PrePost. Material properties were taken from reference guides, research papers, …

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An Overview Of Ceramic Molds For Investment Casting Of Nickel Superalloys, Janos E. Kanyo, Stefan Schafföner, R. Sharon Uwanyuze, Kaitlynn S. Leary Dec 2020

An Overview Of Ceramic Molds For Investment Casting Of Nickel Superalloys, Janos E. Kanyo, Stefan Schafföner, R. Sharon Uwanyuze, Kaitlynn S. Leary

Materials Science and Engineering Faculty Research & Creative Works

Accelerating advancements in technological systems have demonstrated a need for alloys with drastically improved thermomechanical and chemical properties, called superalloys. Ceramic molds are typically used in near-net shape investment casting processes of superalloy components due to their chemical inertness and high-temperature capabilities. Ceramic molds, however, often suffer from shortcomings in vital properties including flexural strength, thermal shock resistance, permeability, dimensional stability, corrosion resistance, and leachability, which have restricted their ability to adequately process modern alloy castings. This study analyses these limitations and illustrates how to address them, particularly regarding ceramic mold and slurry design, processing of shells and cores, material …

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Optimization And Characterization Of Novel Injection Molding Process For Metal Matrix Syntactic Foams, Myranda Spratt, Joseph William Newkirk Dec 2020

Optimization And Characterization Of Novel Injection Molding Process For Metal Matrix Syntactic Foams, Myranda Spratt, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Metal matrix syntactic foams are particulate composites comprised of hollow or porous particles embedded in a metal matrix. These composites are difficult to manufacture due primarily to the lightweight, relatively fragile filler material. In this work, an injection molding process was developed for metal matrix syntactic foams. First, an aqueous binder was optimized for low-pressure injection molding. A mixture model was used to optimize the composition of the binder to achieve the highest relative density. The model predicted the maximum relative density was at a binder composition (in vol.%) of 7% agar, 4% glycerin, and 89% water. Second, this binder …

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3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim Dec 2020

3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim

Faculty Publications

This paper presents 3-D Fabry–Pérot (FP) cavities fabricated directly onto cleaved ends of low-loss optical fibers by a two-photon polymerization (2PP) process. This fabrication technique is quick, simple, and inexpensive compared to planar microfabrication processes, which enables rapid prototyping and the ability to adapt to new requirements. These devices also utilize true 3-D design freedom, facilitating the realization of microscale optical elements with challenging geometries. Three different device types were fabricated and evaluated: an unreleased single-cavity device, a released dual-cavity device, and a released hemispherical mirror dual-cavity device. Each iteration improved the quality of the FP cavity's reflection spectrum. The …

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Review Of Γ’ Rafting Behavior In Nickel-Based Superalloys: Crystal Plasticity And Phase-Field Simulation, Zhiyuan Yu, Xinmei Wang, Fuqian Yang, Zhufeng Yue, James C. M. Li Nov 2020

Review Of Γ’ Rafting Behavior In Nickel-Based Superalloys: Crystal Plasticity And Phase-Field Simulation, Zhiyuan Yu, Xinmei Wang, Fuqian Yang, Zhufeng Yue, James C. M. Li

Chemical and Materials Engineering Faculty Publications

Rafting is an important phenomenon of the microstructure evolution in nickel-based single crystal superalloys at elevated temperature. Understanding the rafting mechanism and its effect on the microstructure evolution is of great importance in determining the structural stability and applications of the single crystal superalloys. Phase-field method, which is an excellent tool to analyze the microstructure evolution at mesoscale, has been gradually used to investigate the rafting behavior. In this work, we review the crystal plasticity theory and phase-field method and discuss the application of the crystal plasticity theory and phase-field method in the analysis of the creep deformation and microstructure …

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The Economics Of Classroom 3-D Printing Of Open-Source Digital Designs Of Learning Aids, Nicole Gallup, Joshua M. Pearce Nov 2020

The Economics Of Classroom 3-D Printing Of Open-Source Digital Designs Of Learning Aids, Nicole Gallup, Joshua M. Pearce

Michigan Tech Publications

While schools struggle financially, capital for purchasing physical learning aids is often cut. To determine if costs could be reduced for learning aids, this study analyzed classroom-based distributed digital manufacturing using 3-D printing of open-source learning aid designs. Learning aid designs are analyzed in detail for their economic viability considering printing and assembly costs with purchased components and compared to equivalent or inferior commercial products available on Amazon. The results show current open-source 3-D printers are capable of manufacturing useful learning aids and that doing so provides high economic savings in the classroom. Overall, the average learning aid would save …

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Water Conservation Potential Of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics, Kaomi Soulemane Hayibo, Pierce Mayville, Ravneet Kaur Kailey Nov 2020

Water Conservation Potential Of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics, Kaomi Soulemane Hayibo, Pierce Mayville, Ravneet Kaur Kailey

Michigan Tech Publications

A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per …

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A First Investigation Of Agriculture Sector Perspectives On The Opportunities And Barriers For Agrivoltaics, Alexis Pascaris, Chelsea Schelly, Joshua M. Pearce Nov 2020

A First Investigation Of Agriculture Sector Perspectives On The Opportunities And Barriers For Agrivoltaics, Alexis Pascaris, Chelsea Schelly, Joshua M. Pearce

Michigan Tech Publications

Agrivoltaic systems are a strategic and innovative approach to combine solar photovoltaic (PV)-based renewable energy generation with agricultural production. Recognizing the fundamental importance of farmer adoption in the successful diffusion of the agrivoltaic innovation, this study investigates agriculture sector experts’ perceptions on the opportunities and barriers to dual land-use systems. Using in-depth, semistructured interviews, this study conducts a first study to identify challenges to farmer adoption of agrivoltaics and address them by responding to societal concerns. Results indicate that participants see potential benefits for themselves in combined solar and agriculture technology. The identified barriers to adoption of agrivoltaics, however, include: …

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Aerosol Jet Printed Capacitive Strain Gauge For Soft Structural Materials, Kiyo T. Fujimoto, Jennifer K. Watkins, Timothy Phero, Takoda Bingham, Kshama Lakshmi Ranganatha, Benjamin C. Johnson, Zhangxian Deng, Brian Jaques, David Estrada Nov 2020

Aerosol Jet Printed Capacitive Strain Gauge For Soft Structural Materials, Kiyo T. Fujimoto, Jennifer K. Watkins, Timothy Phero, Takoda Bingham, Kshama Lakshmi Ranganatha, Benjamin C. Johnson, Zhangxian Deng, Brian Jaques, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

Soft structural textiles, or softgoods, are used within the space industry for inflatable habitats, parachutes and decelerator systems. Evaluating the safety and structural integrity of these systems occurs through structural health monitoring systems (SHM), which integrate non-invasive/non-destructive testing methods to detect, diagnose, and locate damage. Strain/load monitoring of these systems is limited while utilizing traditional strain gauges as these gauges are typically stiff, operate at low temperatures, and fail when subjected to high strain that is a result of high loading classifying them as unsuitable for SHM of soft structural textiles. For this work, a capacitance based strain gauge (CSG) …

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Machine Learning Augmentation Micro-Sensors For Smart Device Applications, Mohammad H. Hasan Nov 2020

Machine Learning Augmentation Micro-Sensors For Smart Device Applications, Mohammad H. Hasan

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Novel smart technologies such as wearable devices and unconventional robotics have been enabled by advancements in semiconductor technologies, which have miniaturized the sizes of transistors and sensors. These technologies promise great improvements to public health. However, current computational paradigms are ill-suited for use in novel smart technologies as they fail to meet their strict power and size requirements. In this dissertation, we present two bio-inspired colocalized sensing-and-computing schemes performed at the sensor level: continuous-time recurrent neural networks (CTRNNs) and reservoir computers (RCs). These schemes arise from the nonlinear dynamics of micro-electro-mechanical systems (MEMS), which facilitates computing, and the inherent ability …

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Laser Powder Bed Fusion Of Nitihf High-Temperature Shape Memory Alloy: Effect Of Process Parameters On The Thermomechanical Behavior, Mohammadreza Nematollahi, Guher P. Toker, Keyvan Safaei, Alejandro Hinojos, S. Ehsan Saghaian, Othmane Benafan, Michael J. Mills, Haluk E. Karaca, Mohammad Elahinia Nov 2020

Laser Powder Bed Fusion Of Nitihf High-Temperature Shape Memory Alloy: Effect Of Process Parameters On The Thermomechanical Behavior, Mohammadreza Nematollahi, Guher P. Toker, Keyvan Safaei, Alejandro Hinojos, S. Ehsan Saghaian, Othmane Benafan, Michael J. Mills, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Laser powder bed fusion has been widely investigated for shape memory alloys, primarily NiTi alloys, with the goal of tailoring microstructures and producing complex geometries. However, processing high temperature shape memory alloys (HTSMAs) remains unknown. In our previous study, we showed that it is possible to manufacture NiTiHf HTSMA, as one of the most viable alloys in the aerospace industry, using SLM and investigated the effect of parameters on defect formation. The current study elucidates the effect of process parameters (PPs) on the functionality of this alloy. Shape memory properties and the microstructure of additively manufactured Ni-rich NiTiHf alloys were …

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A Bibliometric Survey On Polymer Composites In Energy Storage Applications, Babaji Ghule, Meena Laad Nov 2020

A Bibliometric Survey On Polymer Composites In Energy Storage Applications, Babaji Ghule, Meena Laad

Library Philosophy and Practice (e-journal)

Ceramic polymer composites have gained a significant place in energy storage applications for electrical capacitors due to their distinguished properties. There is a huge demand of capacitors with high energy density, high dielectric strength, negligibly low dielectric loss, light weight, chemically less reactive in energy storage applications. These requirements can be fulfilled by ceramic polymer composites only which exhibit all the above-mentioned characteristics. Considering the huge demand of such capacitors, it has attracted the attention of researchers around the world. The present work attempts to summarise all the research conducted on Polymer Composites for energy storage applications and provides an …

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Desorption From Hot Scandate Cathodes: Effects On Vacuum Device Interior Surfaces After Long-Term Operation, Mujan N. Seif, Thomas John Balk, Matthew J. Beck Nov 2020

Desorption From Hot Scandate Cathodes: Effects On Vacuum Device Interior Surfaces After Long-Term Operation, Mujan N. Seif, Thomas John Balk, Matthew J. Beck

Chemical and Materials Engineering Faculty Publications

Scandate cathodes have exhibited superior emission properties compared to current state-of-the-art “M-type” thermionic cathodes. However, their integration into vacuum devices is limited in part by a lack of knowledge regarding their functional lifespan and behavior during operation. Here, we consider thermal desorption from scandate cathodes by examining the distribution of material deposited on interior surfaces of a sealed vacuum device after ~26,000 h of cathode operation. XPS, EDS, and TEM analyses indicate that on the order of 1 wt.% of the initial impregnate is desorbed during a cathode’s lifetime, Ca does not desorb uniformly with time, and little to no …

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Effects Of Laser Power And Substrate On The Raman Shift Of Carbon-Nanotube Papers, Fuqian Yang, Shanshan Wang, Yuling Zhang Nov 2020

Effects Of Laser Power And Substrate On The Raman Shift Of Carbon-Nanotube Papers, Fuqian Yang, Shanshan Wang, Yuling Zhang

Chemical and Materials Engineering Faculty Publications

The progress in the fabrication of carbon-nanotube-based structures has made it possible to use Raman spectroscopy to measure the deformation states of carbon nanotubes and abutting materials. In this work, we investigate the effects of laser power and surrounding materials on the Raman shift of carbon-nanotube (CNT) papers for the laser intensity in a range of 0.071 to 1.415 kW/mm2 without action of mechanical loading. Two different configurations of the CNT papers are used in the Raman measurement; one uses a suspended CNT paper, and the other places a CNT paper on a glass or aluminum substrate. The experimental …

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Proximity-Induced Magnetization In Graphene: Towards Efficient Spin Gating, Mihovil Bosnar, Ivor Lončarić, P. Lazić, Kirill Belashchenko, Igor Žutić Nov 2020

Proximity-Induced Magnetization In Graphene: Towards Efficient Spin Gating, Mihovil Bosnar, Ivor Lončarić, P. Lazić, Kirill Belashchenko, Igor Žutić

Kirill Belashchenko Publications

Gate-tunable spin-dependent properties could be induced in graphene at room temperature through the magnetic proximity effect by placing it in contact with a metallic ferromagnet. Because strong chemical bonding with the metallic substrate makes gating ineffective, an intervening passivation layer is needed. Previously considered passivation layers result in a large shift of the Dirac point away from the Fermi level, so that unrealistically large gate fields are required to tune the spin polarization in graphene (Gr). We show that a monolayer of Au or Pt used as the passivation layer between Co and graphene brings the Dirac point closer to …

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Detection Of Uncompensated Magnetization At The Interface Of An Epitaxial Antiferromagnetic Insulator, Pavel N. Lapa, Min Han Lee, Igor V. Roshchin, Kirill Belashchenko, Ivan K. Schuller Nov 2020

Detection Of Uncompensated Magnetization At The Interface Of An Epitaxial Antiferromagnetic Insulator, Pavel N. Lapa, Min Han Lee, Igor V. Roshchin, Kirill Belashchenko, Ivan K. Schuller

Kirill Belashchenko Publications

We have probed directly the temperature and magnetic field dependence of pinned uncompensated magnetization at the interface of antiferromagnetic FeF2 with Cu, using FeF2-Cu-Co spin valves. Electrons polarized by the Co layer are scattered by the pinned uncompensated moments at the FeF2-Cu interface giving rise to giant magnetoresistance. We determined the direction and magnitude of the pinned uncompensated magnetization at different magnetic fields and temperatures using the angular dependencies of resistance. The strong FeF2 anisotropy pins the uncompensated magnetization along the easy axis independent of the cooling field orientation. Most interestingly, magnetic fields as …

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Organic-Inorganic Halide Perovskite Nanocrystals And Solar Cells, Rui Guo Nov 2020

Organic-Inorganic Halide Perovskite Nanocrystals And Solar Cells, Rui Guo

FIU Electronic Theses and Dissertations

A great challenge facing humanity in the 21st century is finding inexhaustible and inexpensive energy sources to power the planet. Renewable energies are the best solutions because of their abundance, diversity, and pollution-free emission. Solar energy is the cleanest and most abundant renewable energy source available. In the continuing quest for efficient and low-cost solar cells, perovskite solar cells (PSCs) have emerged as a potential replacement for silicon solar cells. Since 2009, the record efficiencies of PSCs have been skyrocketing from 3.8 % to 25.2 % and are now approaching the theoretical limit. Along with the three-dimensional perovskites used …

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Effects Of Inert Additives On Cyclotrimethylene-Trinitramine (Rdx)/Trinitrotoluene (Tnt) Detonation Parameters To Predict Detonation Synthesis Phase Production, Martin Langenderfer, William Fahrenholtz, Catherine E. Johnson Nov 2020

Effects Of Inert Additives On Cyclotrimethylene-Trinitramine (Rdx)/Trinitrotoluene (Tnt) Detonation Parameters To Predict Detonation Synthesis Phase Production, Martin Langenderfer, William Fahrenholtz, Catherine E. Johnson

Materials Science and Engineering Faculty Research & Creative Works

A methodology was developed to predict pressure and temperature regimes achieved during detonation of RDX/TNT compositions with inert granular inclusions. The predicted pressures and temperatures are used as inputs for thermochemical simulations to design detonation synthesis experiments that utilize shock-induced chemical reactions to produce ceramic nanomaterials. This study computationally assessed the effects of inert spherical sand inclusions and porosity produced by inert additives on the sensitivity of the explosive composition during the shock-to-detonation transition using a limited scope approach through Lee-Tarver ignition and growth modeling. On the continuum scale, the effects of inert additives on pressure generation behind the detonation …

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Reinvestigation Of The Intrinsic Magnetic Properties Of (Fe1-Xcox)2b Alloys And Crystallization Behavior Of Ribbons, Tej Nath Lamichhane, Olena Palasyuk, Vladimir P. Antropov, Ivan A. Zhuravlev, Kirill Belashchenko, Ikenna C. Nlebedim, Kevin W. Dennis, Anton Jesche, Matthew J. Kramer, Sergey L. Bud'ko, R. William Mccallum, Paul C. Canfield, Valentin Taufour Nov 2020

Reinvestigation Of The Intrinsic Magnetic Properties Of (Fe1-Xcox)2b Alloys And Crystallization Behavior Of Ribbons, Tej Nath Lamichhane, Olena Palasyuk, Vladimir P. Antropov, Ivan A. Zhuravlev, Kirill Belashchenko, Ikenna C. Nlebedim, Kevin W. Dennis, Anton Jesche, Matthew J. Kramer, Sergey L. Bud'ko, R. William Mccallum, Paul C. Canfield, Valentin Taufour

Kirill Belashchenko Publications

New determination of the magnetic anisotropy from single crystals of (Fe1-xCox)2B alloys are presented. The anomalous temperature dependence of the anisotropy constant is discussed using the standard Callen-Callen theory, which is shown to be insufficient to explain the experimental results. A more material specific study using first-principles calculations with disordered moments approach gives a much more consistent interpretation of the experimental data. Since the intrinsic properties of the alloys with x=0.3-0.35 are promising for permanent magnets applications, initial investigation of the extrinsic properties are described, in particular the crystallization of melt spun ribbons with Cu, Al, …

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