Journal of Undergraduate Materials Research

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Aerogel Fabrics in Advanced Space Suit Applications
Crowell, Cameron; Reynolds, Cameron; Stutts, Andrew; Taylor, Hunter (Virginia Tech Department of Materials Science and Engineering, 2015-01-01)
New insulating materials for spacesuits will need to be able to function well in low-pressure and gaseous environments, such as the Martian atmosphere. In order to address this need, Orbital Outfitters, a small spacesuit company, is currently investigating new materials for the insulating layer of the space suit. One such material is an aerogel fabric composite, promising because of its flexibility and low thermal conductivity. The purpose of this study is to characterize the effect stitching an outer layer has on the stiffness, strength, and thermal conductivity of two types of aerogel fabric, ThermalWrap and Pyrogel 2250. Tension tests were used to investigate the mechanical properties, while two different methods were used to evaluate the thermal conductivity of the materials. Results showed a dramatic increase of thermal conductivity when an outer material was stitched directly to the aerogel fabric, while two other geometries showed a decrease in thermal conductivity. Tension tests revealed that stitching increased the strength of the ThermalWrap. Overall, it was determined that stitching the material was not a viable option due to the increase in thermal conductivity and difficult manufacturing. The two other geometries tested proved much more effective, as they were easier to manufacture and showed a decrease in thermal conductivity.
Bacterial Cellulose as a Potential Bone Graft
Lowman, Kennedi (Virginia Tech Department of Materials Science and Engineering, 2015-01-01)
Each year tissue engineering costs the United States $2 million dollars. Bacterial Cellulose (BC), a hydrogel with a fine fiber network, is produced by the bacterium Acetobacter xylinum that can be used as a protective coating. In contrast to other polymers, BC possesses high tensile strength, high water holding capabilities, and high mechanical properties. The purpose of the current study is to determine if individual fibers of BC can be functionalized with calcium by applying an electric field. BC was grown and calcium was deposited simultaneously using Corn Steep Liquor (CSL) media, with the addition of fructose, in channels 4 cm long x 5 mm wide x 2.5 mm deep. The channels contained platinum electrodes supplying an electric field of 3 to 7.5 volts for 72 hours in the presence of CaCl2. BC pellicles formed and were then examined using the Environmental Scanning Electron Microscope (ESEM). Energy-Dispersive X-ray Spectroscopy (EDS) was also used to determine the composition in each sample. Calcium was found deposited on the BC fibers at 5.5 volts. Lower voltages, such as 4.0 volts, resulted in no calcium deposition on the fibers. The presence of Carboxymethyl Cellulose (CMC) is critical for the calcium deposition. Calcium deposition will occur at 5.5 volts suggesting there may be a specific electric field requirement for calcium deposition on BC.
Biocompatibility and Hardness of Ti-Hf and Diamond-like Carbon Coatings for Orthopedics
Kuhn, Stephanie (Virginia Tech Department of Materials Science and Engineering, 2008-03-20)
Every year, about 300,000 total hip replacement (THR) surgeries are performed in the United States.The typical lifespan of an implant ranges between 10 and 20 years, with implant failures largely due to materials issues such as biocompatibility, wear, corrosion, and premature stress failures.The objective of this research is to examine the feasibility of using a new class of materials, namely Ti-Hf alloys and low friction diamond-like carbon (DLC) coatings, for improving the performance of orthopedic devices.Biocompatibility and hardness tests were performed, which showed Hf did not adversely affect the biocompatibility of Ti and that the DLC coating did not adversely affect the biocompatibility of the Ti-Hf alloy.Furthermore, the biocompatibility of the Ti-Hf alloy was comparable to that of Ti-6Al-4V.The research was done as a collaborative effort between the College of Engineering and the School of Veterinary Medicine at the University of Wisconsin – Madison and NASA Glenn, Cleveland, OH.
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.
Biomorphic Materials: Silicon Carbide Derived from Natural Carbon Precursors
Surbey, Wyatt (Virginia Tech Department of Materials Science and Engineering, 2015-01-01)
The recent initiative to cater toward an environmentally efficient lifestyle has put pressure on many industries and practices. However, the success of these green initiatives has not been an easy achievement. During the past decade, scientists and engineers have worked tirelessly to discover a more natural way to process Silicon Carbide (SiC). A new category of materials, called biomorphic materials, has provided insight into how materials can be synthesized from bio-organic materials while retaining similar properties and performance. In comparing SiC with its biomorphic cousin, BioSiC, there are notable similarities and differences in the properties, structure, processing, performance, and environmental concerns between each material discussed in this article.
Characterization of Electrolessly Plated Graphite Foams with Particle Additions
Asaro, Michael; Mueller, Jennifer; Dykema, Patrick (Virginia Tech Department of Materials Science and Engineering, 2008-03-20)
With a low density and high bulk thermal conductivity, graphite foams are ideal for thermal management systems such as computer heat sinks, radiators, and heat exchangers.Previous work has shown it is possible to improve the foams performance by opening the porosity with nanoparticle additions in the foams precursor, an oil based mesophase pitch.[1] The open porosity allows more fluid, such as air or water, to pass through the foam and carry heat away.The original study, performed by Jennifer Mueller at Oak Ridge National Labs (ORNL), considered the concentrations of nanoparticle’s used.The present study looked to determine the effects of using different types of nanoparticles at a range of sizes from the nano- to micro- level.The study began by adding, respectively, silver, ceria, alumina, tungsten, and nickel to different batches of mesophase pitch at a single weight percent concentration to create graphite foams with a significant amount of continuous porosity.The pitch was foamed, carbonized, and graphitized.The final foam products were then measured in a variety of ways including thermal conductivity, permeability, and scanning electron microscope (SEM).As a side project, an electroless copper plating solution was passed through the foams to determine if a continuous and uniform copper coating could be built up.The copper coating that was eventually obtained coated the foam walls without filling the open porosity and may help to increase the foams solderability, strength, durability, and corrosion resistance.
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.
Chitosan: An Antimicrobial Polymer
Venkatraman, Priya (Virginia Tech Department of Materials Science and Engineering, 2015-01-01)
Antibiotic resistant infections are a rising problem in the United States and globally. These infections are listed as a top concern by the Center for Disease Control and Prevention (CDC) as well as by the World Health Organization. Antibiotic resistance is a phenomenon where microorganisms acquire or innately possess resistance to antimicrobial agents. Antibiotic resistant infections significantly reduce the effectiveness of the treatment causing patients to remain infectious longer and increasing the risk of spreading the resistant microorganisms. Antibiotic resistant infections are incredibly detrimental to society and are threatening many of the medical advances made in the past century.
Collaborative Learning: Enhancing the Undergraduate Research Experience
Webster, Katelyn; Gervacio, Aimee (Virginia Tech Department of Materials Science and Engineering, 2010-03-20)
Music has always united people through concerts, operas, and camp fires. For two universities, music brings together undergraduate students despite 615 miles of separation. Engineering students at Virginia Tech and the University of Hartford are working together on a music-inspired project that hopes to discover a new method for coating guitars. While this project connects the fields of engineering and the arts, it also yields benefits for students and faculty through collaborative learning efforts.
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.
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.
Developing Functional Inks for Direct-Write Systems
Rodriguez, Mitchell (Virginia Tech Department of Materials Science and Engineering, 2010-03-20)
The field of Flexible Printed Electronics (FPE) carries great potential in reducing manufacturing costs and increasing versatility. The purpose of this research is to explore various ink chemistries and their suitability for deposition with regards to FPE. Titanium ceramics and silver-titanium-iron nanoparticles were utilized for their potential photocatalytic properties. The resulting inks experienced phase separation or hydrolyzed upon exposure to moisture, suggesting that a surfactant-based synthesis would better improve the inks’ durability.
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.
Domain Wall Collision-Induced Spin Waves
Delaney, Tristain (Virginia Tech Department of Materials Science and Engineering, 2015-01-01)
A series of micromagnetic simulations are conducted whereby two transverse domain walls are injected into a straight magnetic nanowire under an applied field. It is found that, based on the relative orientation of the domain walls, the two may annihilate, resulting in the generation of an intense spin-wave burst. Since the applied magnetic fields for these simulations are smaller than the Walker breakdown field, these results present an extremely low-energy means of generating and controlling spin waves for engineering applications.
The Dynamics of Periodically Forced Prolate Spheroids in a Quiescent Newtonian Fluid with Weak Inertia
Kumar, Priyank (Virginia Tech Department of Materials Science and Engineering, 2010-03-20)
The effects of convective and unsteady inertia on the dynamics of periodically forced neutrally buoyant prolate spheroids in a quiescent Newtonian fluid medium, at low Reynolds numbers have been modeled. The resulting nonlinear equations have been solved using appropriate numerical methods. Several tests including a perturbation analysis are performed to validate results. A preferred direction, which is identified as the initial direction of motion, is observed that manifests itself in the properties of the solution. Results of the behavior of various parameters with respect to the Reynolds number, aspect ratio of the spheroid and the amplitude of the periodic force are presented. The results are technologically important as they may lead to insights in the development of active dampeners and smart fluids.
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.
The Effect of Cornstarch Levels on the Surface Quality of Extruded Soy Protein Plastic
Ziolkowski, Evan (Virginia Tech Department of Materials Science and Engineering, 2008-03-20)
The ratio of soy protein isolate to cornstarch was studied in the extrusion of four different formulations of soy protein plastic in order to qualitatively examine the surface quality upon extrusion.Levels of glycerol and moisture were constant across all samples, and no other additives were used in the mixtures.Mixtures were made using a planetary mixer, and then extruded using a single-screw extruder equipped with a 10.16 centimeter sheeting die with a 0.152-centimeter opening.The surface of the extruded plastic became smoother with increasing starch content, but the processability became too difficult with very high starch levels.
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.
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.
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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