Browsing by Author "Poquette, Ben"

Now showing 1 - 20 of 28
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    Biological Self-Assembled Porous Ceramics as High Temperature Insulation in Steam Transport Pipes
    Price, Seth; Marier, Elizabeth (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    Biological self-assembled porous ceramics could serve as a substitute for asbestos in thermally insulating applications, such as steam transport pipes in coal-fired power plants. To become a viable alternative to asbestos, a biologically self-assembling ceramic would have good thermal stability up to 650℃, have low thermal conductivity, and be nontoxic and light weight. Ball clay was chosen as the base for the ceramic. By adjusting the amounts of water, yeast, salt, and sugar in the slurry, the sample with the lowest density was found, as it would be most likely to yield the highest porosity, and thus lowest thermal conductivity.
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    Characterization of the Effect of Film Thickness on the Electrochemical Impedance of Nanoporous Gold
    Bell, Nicholas; Collins, James; Turner, Ryan (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    Graphs are generated characterizing the effect of film thickness on the electro­ chemical impedance of nanoporous gold. Twelve-karat white gold (50% Ag, 50% Au) leaves were dealloyed to make a total of 12 nanoporous gold samples from 100­ 300 nm thick. Scanning electron microscopy (SEM) was used to determine the pore diameter distributions and an electrochemical cell was used to collect impedance data for each sample. Analysis of the SEM micrographs shows the pore morphology ranges from shallow spherical pores to deep interconnected pores, and the diameter distributions were between 10 nm and 20 nm for all of the samples. A linearized graph of impedance |Z| versus frequency shows that the breakpoint frequency decreases with increasing film thickness. Below the breakpoint frequency, the data support an idealized model that assumes through-thickness pores with uniform diameters. Above the breakpoint frequency, however, the ideal model predicts a drastic imped­ance decrease, whereas the data show only a slight impedance decrease.
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    Computer Simulation of a Hardness Indent Test into Nickel Nano Thin Films
    Parker, Edward; Gaudreau, Peter (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Current experiments suggest that mechanical properties of thin films are different at thicknesses less than 100 nm.In this study, embedded atom method computer simulations are used to examine the differences in strengthening mechanisms at the nano scale.The simulation shows the mechanisms responsible for the differences in hardness with varying sample thicknesses from 12.8, 8, 6, and 4 nm.The simulation results show that as film thickness decreases the hardness of the film increases.Simulations were performed in single crystal films as well as model tricristals in order to study the effects of the grain boundaries.Tricrystalline films emitted dislocations at a lower pressure than single crystals.
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    Deposition and Single-Step Processing of YBCO Thick Films for Multilayered Electronics
    Langman, Jonathan; Lynch, Matthew (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    The goal of this project was to successfully cofire a screen-printed yttrium bar ium copper oxide (YBCO) superconductor onto a low-temperature cofired ceramic (LTCC) substrate. The purpose was to investigate the compatibility of thick-film, high-temperature superconductors with multilayered ceramic (MLC) packages for cryogenic applications. Paste consisting of standard organics and YBCO powder of -325 mesh particle size was screen-printed onto Dupont 951 Green Tape. The system was cofired at temperatures ranging from 925°C to 975°C. The quality of the cofired system was characterized in several ways: Meissner diamagnetism, scanning electron microscopy, x-ray diffraction, and AC susceptibility tests were performed to determine the superconducting capability of the system. Samples cofired at 950°C retained some superconductivity after firing and showed the best compromise be­tween sintering and degradation.
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    Determining the Role of Porosity on the Thermal Properties of Graphite Foam
    Mueller, Jennifer Elizabeth (Virginia Tech, 2008-07-10)
    Graphite foams have high bulk thermal conductivity and low density, making them an excellent material for heat exchanger applications. This research focused on the characterization of graphite foams under various processing conditions (different foaming pressures and particle additions), specifically studying the effects of porosity on the thermal properties. The characterization of the foams included measuring cell sizes, percent open porosity, number of cells per square inch, bulk density, Archimedes density, compression strength, thermal conductivity, thermal resistance, and permeability. Several relationships between the structure and properties were established, and a recommendation for the processing conditions of graphite foams for the use in heat exchangers was determined.
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    DISCOVERIES AND BREAKTHROUGHS INSIDE SCIENCE: Bringing science from the laboratory to the living room
    Martin, Lane; Hickey, Diane; Poquette, Ben; Jones, Kevin; Floro, Jerrold (Virginia Tech Department of Materials Science and Engineering, 2008-03-20)
    Have you ever kicked back to watch your favorite sciencebased TV programming and had the thought, “That’s not so hard, I could do that.” With the help of a partnership between the National Science Foundation (NSF), the American Institute of Physics (AIP), 19 professional scientific organizations, including the Materials Research Society (MRS), and Ivanhoe Broadcast Network, Inc., you might have the chance to be a science-star for a day and to bring your work in the laboratory to the living rooms of millions of American television viewers.
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    Effect of Carbon Addition and Sintering Temperatures on Densification and Microstructural Evolution of Sinter-Hardening Alloy Steels
    Verma, Neerav; Anand, Saurabh (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    The iron-copper-carbon alloys are used extensively in powder metallurgy due to their superior dimensional control; however, they possess lower mechanical properties, corrosion resistance and wear resistance than their wrought counter part.In recent years, there have been concerted attempts to engineer ferrous alloys with high dimension tolerance and enhanced mechanical properties.One such approach is to use prealloyed iron powder instead of pure iron, mixed with copper and carbon.SH737-2Cu-C is one such alloy.The present study focuses on the effect of carbon addition on diffusion of Cu in SH737 alloys system via microstructural studies.SH737-2Cu alloys were compacted, sintered and characterized.The materials were characterized according to their density, densification parameter, shape factor, and pore size distribution.The microstructural studies revealed bimodal pore distribution in the sample with no carbon, due to the presence of primary and secondary porosity.The shape factor distribution showed more roundedness in the case of carbon added alloys.The size of the primary pores depends on compaction pressure and powder size distribution.On the other hand, size and morphology of the secondary pore strongly depends on Cu powder size, its homogeneity and sintering temperature.Also, an increase in the sintering temperature increased the roundedness and the pores became coarser.
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    Effect of Sintering Temperature, Heat Treatment, and Tempering on Hardness of Sintered Hardened Grade Steels
    Anand, Saurabh; Verma, Neerav (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    The present study examines the change in hardness of sintered hardened steel (SH737-2Cu-0.9C) sintered at different temperatures, heat treated by various methods and then tempered at different temperatures.The samples were transient liquid phase sintered at 1120 °C, 1180 °C and 1250 °C respectively.The sintered samples were characterized then for density and densification parameter.The samples were austenitized at 900 °C and cooled by four different methods viz.furnace cooling (annealing), air cooling (normalizing), oil quenching, and brine quenching.The samples were then tested for their hardness using Vickers’s hardness at 10 kgf load.The trend of hardness observed was found minimum for air cooled and maximum for brine quenched.In case of sample sintered at 1250 °C, relatively higher hardness was observed.The oil and brine quenched samples were then tempered at 200 °C, 400 °C, 600 °C and 700 °C.The hardness pattern observed typically showed secondary hardness taking place (due to presence of Mn and Mo) and reaching the maximum around 600 °C.
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    The Effect of Viscosity and Ion Size on the Transduction of Ionic Polymer Metal Composite Actuators
    Copley, Lisa; Hubbard, Elizabeth; Maisano, Adam (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    Ionic polymer membranes plated with platinum and gold serve as actuators when a small potential is applied. However, the water used to hydrate the membrane evaporates during use, decreasing actuator performance. Ionic liquids are being considered as a replacement for water because of their low vapor pressure. Prior studies show that the large ion size and high viscosity of ionic liquids slow the response time of the polymer membrane when a voltage is applied. This study examines the relationships of ion size and viscosity to transduction by modeling ionic liquids with inexpensive salts of varying ion size and glycerol/water solutions. Based on these results several ionic liquids were selected and tested for use as membrane sol­ vents. This study includes frequency response, step response, and impedance tests of samples impregnated with Li+, K+, Cs+, TMA+, TEA+, and TBA+. Actuators solvated in solutions with a viscosity similar to 70–80 wt. % glycerol solutions (18–46 cP) and cation size similar to that of TMA+ (0.347 nm) appear to yield the best results. When used as the membrane solvent, the ionic liquid 1-ethyl-3-methyl imidazolium trifluoromethanesulfonate (IL #3) resulted in the greatest strain per charge per area of the three ionic liquids tested in this study.
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    Engineering Students Design Composite Bracing System for the Virginia Tech Athletic Department
    Kyriakides, Steven (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Engineering Students Design Composite Bracing System for the Virginia Tech Athletic Department.
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    Experimental Simulation of High Energy-Density Plasma Interaction with Liquid Metal Media for Inertial Fusion Reactor First Wall Studies
    Martin, Elijah (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Inertial confinement fusion (ICF) is a promising technology positioned to address the future energy needs of the world.An advanced design concept for ICF reactors is to use a circulating liquid barrier to protect the first wall of the target chamber.With the impaction of the high energy-density plasma on the liquid barrier, sputtering and vaporization can occur causing particulate matter to enter the target chamber interior volume.In order to best engineer the design of the target chamber, this interaction must be well characterized.A small-size experimental facility was designed, constructed, and operated at NC State University to simulate the interaction of high energy-density plasma with liquid metals.This study focuses on characterization of the plasma-liquid metal plume.Characterization of the generated plumes shape and size of evolved vaporized liquid metal particulates; density and other plasma parameters were studied in this research.Electrical and spectral data were obtained for each experiment to obtain the plasma parameters including total power, impedance, electron temperature and density and identification of species.It was determined that a typical plasma generated from a 2 kV discharge has a temperature of 1.0 ± 0.3 eV and a density of 4.2 ± 1.7 x 1017 cm-3.The height and geometric configurations of the collection substrates were changed to produce a model of the generated metallic plume.Data analysis of the substrates indicates that the plume has a higher density profile and smaller particulates at distances closer to the point of impact, and the particulate size increases and the particulate density profile decreases with increased distance from liquid metal pool.
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    A Guide to the Calculation of Theoretical Densities of Crystal Structures for Solid Oxide Fuel Cells
    Rosten, Rachel; Koski, Matt; Koppana, Eric (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Theoretical density is an important parameter used to estimate the porosity of materials after sintering, especially if the requirements for the materials’ densities are strict, such as in the case of the parts of solid oxide fuel cells.In this research paper, we provide examples of theoretical density calculations using unit cell structure and X-ray diffraction determined lattice parameters for a number of different ceramics, which are important for energy applications.Oxide perovskites, fluorites and rock salts were all investigated.
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    Industry Insider: Micron Technology, Inc.
    Pritchard, Jessica (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Micron Technology, Inc., founded by Ward Parkinson, Joe Parkinson, Dennis Wilson, and Doug Pitman in 1978, stands as one of the leading international providers of advanced semiconductor solutions, producing various semiconductor devices.Such devices include DRAM (dynamic random access memory) components, flash components, and CMOS (complementary metal oxide semiconductor) image sensors.With a strong focus on materials research, Micron continues to create next generation digital technology, pushing the boundaries of new imaging technology.In fact, Micron continues to hire recent graduates from around the country in materials related fields including chemical, electrical, computer, and materials engineering, as well as physics, and with their help, created one of the industry’s first 1.7 micron-pixel image sensors.
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    Journal of Undergraduate Materials Research, Vol. 1 (2005)
    (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    The Journal of Undergraduate Materials Research (JUMR) is a student-run scientific journal dedicated to research performed by students in materials science and related fields. The primary goal of this journal is to provide a platform for undergraduate researchers to publish their work. The secondary goal of this journal is to provide opportunities for undergraduates to practice their communication skills and gain experience working with reviewed publications. The following is the Alfred Knobler Inaugural Issue of the Journal of Undergraduate Materials Research (JUMR). This issue, guided by the goals of Alfred Knobler, is the product of collaborative effort between the Virginia Tech Department of Materials Science and Engineering and the Virginia Tech Department of English. This issue features a variety of articles and student research focusing on subjects in materials science and engineering.
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    Journal of Undergraduate Materials Research, Vol. 2 (2006)
    (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    The Journal of Undergraduate Materials Research (JUMR) is a student-run scientific journal dedicated to research performed by students in materials science and related fields. The primary goal of this journal is to provide a platform for undergraduate researchers to publish their work. The secondary goal of this journal is to provide opportunities for undergraduates to practice their communication skills and gain experience working with reviewed publications. The second issue of the Journal of Undergraduate Materials Research continues to be a product of collaborative effort between the Virginia Tech Department of Materials Science and Engineering and the Virginia Tech Department of English. This issue features a variety of articles and student research focusing on subjects in materials science and engineering. The papers within this issue represent students from schools including Michigan Tech, North Carolina State University, multiple departments within Virginia Tech, and the Indian Institute of Technology in Kanpur, India.
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    Mechanical Behavior of Nafion and BPSH Membranes
    Kyriakides, Steven (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    A brief characterization of the mechanical behavior of Nafion® 117 and BPSH-35 membranes took place through uniaxial loading, stress relaxation, and creep compliance tests. Membranes were subjected to uniaxial loading at various strain rates to observe yield and fracture behavior. Stress relaxation tests measured relaxation response to strain rate and relaxation strain. Creep compliance tests led to the formation of a creep master curve for the Nafion® membrane. Tests showed that for Nafion®, higher strain rates produced higher yield stresses and yield strains as well as faster initial relaxation. Strain rate had no effect on strain at fracture. Higher re­ laxation strains also led to faster initial stress relaxation in both Nafion® and BPSH. BPSH results showed no yield trends in uniaxial loading, though they illustrated lower breaking strains with higher strain rates.
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    Meet Alfred Knobler
    Holt, Susan (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    Alfred E. Knobler made several generous donations to Virginia Tech for the creation of Knobler scholarships and fellowships. These opportunities are for both undergraduate and graduate students in the Departments of Materials Science and Engineering and English. The purpose of these scholarships is to foster communication and exchange of ideas and skills between these two departments.
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    Microwave Sintering of Simulated Moon Rock
    Hunt, Michael; Ducut, Amy; Lee, Christina (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    The focus of this research was to determine the feasibility of using microwave energy to sinter simulated moon rock.Microwave processing is often used as an alternative to traditional sintering of ceramic materials for its energy efficiency and decreased sintering times.In lunar applications, microwaves would be a more useful for sintering than traditional methods because microwave devices may be transported more easily and with less cost.As found, moon rock does not have the needed physical and thermal properties suitable for its use as a structural material for a lunar base or orbiting structure.[1,2] However, sintered moon rock may have those required characteristics.To evaluate the potential for using microwave energy to sinter simulated moon rock, both stand-alone and hybrid heating methods were tested.Based on collected data, an 1100-watt commercial microwave oven can emit enough energy to rapidly reach the sintering temperature of moon rock using hybrid heating methods.Further research needs to be conducted to compare the physical characteristics of moon rock sintered conventionally and with microwave energy.
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    MSE on the Move
    Suchicital, Carlos T. A. (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    The new Institute for Critical Technology and Applied Science (ICTAS) will attract top faculty and students, foster collaboration between researchers, increase research funding, and provide infrastructure and space to facilitate these aims. The ICTAS Initiative at Virginia Tech (led by the College of Engineering) will involve the construction of several new buildings comprising a multi-disciplinary research laboratory and a 15,000 ft2 state-of-the-art Advanced Materials Characterization Facility (AMCF). The AMCF facility will be formed by a collection of new and existing tools for processing, characterizing, and testing materials at the macro, micro, and nanometer scales. Of the expected cost of $12M in equipment for the AMCF, the University has already provided $3.2M to purchase a High-Resolution Transmission Electron Microscope (HRTEM) and an ion microprobe.
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    Nanotechnology: An Outsider’s Perspective
    Pritchard, Jessica (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Many theorize what the future holds, complete with cliché flying cars and robotic maids, but what if those seemingly imaginary theories became real?Imagine a doctor planning your surgery using a microscopic robot to get into those hardto-reach parts of your body, or better yet—eating a hamburger or hot dog made from your daily garbage.As crazy and futuristic as it may sound, nanotechnology may hold the key to advancing society into a whole new age of technology.Like most sciences, though, there is a flip side:science at such a tiny level, 10-9 meters to be exact, has as many potential dangers as it does advantages.