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Air Force Institute of Technology

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Articles 1 - 30 of 33

Full-Text Articles in Nanoscience and Nanotechnology

Impact Of Silicon Ion Irradiation On Aluminum Nitride-Transduced Microelectromechanical Resonators, David D. Lynes, Joshua Young, Eric Lang, Hengky Chandrahalim Nov 2023

Impact Of Silicon Ion Irradiation On Aluminum Nitride-Transduced Microelectromechanical Resonators, David D. Lynes, Joshua Young, Eric Lang, Hengky Chandrahalim

Faculty Publications

Microelectromechanical systems (MEMS) resonators use is widespread, from electronic filters and oscillators to physical sensors such as accelerometers and gyroscopes. These devices' ubiquity, small size, and low power consumption make them ideal for use in systems such as CubeSats, micro aerial vehicles, autonomous underwater vehicles, and micro-robots operating in radiation environments. Radiation's interaction with materials manifests as atomic displacement and ionization, resulting in mechanical and electronic property changes, photocurrents, and charge buildup. This study examines silicon (Si) ion irradiation's interaction with piezoelectrically transduced MEMS resonators. Furthermore, the effect of adding a dielectric silicon oxide (SiO2) thin film is …

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Influence Of Dilute Silicon Carbide Nanoparticle Additions To The Microstructure And Mechanical Properties Of Laser Powder Bed Fusion Molybdenum, Nathan E. Ellsworth Mar 2023

Influence Of Dilute Silicon Carbide Nanoparticle Additions To The Microstructure And Mechanical Properties Of Laser Powder Bed Fusion Molybdenum, Nathan E. Ellsworth

Theses and Dissertations

Consolidation of pure molybdenum through laser powder bed fusion and other additive manufacturing techniques is complicated by a high melting temperature, thermal conductivity, and ductile-to-brittle transition temperatures. Nano-sized silicon carbide particles (0.1 wt%) were homogeneously mixed with molybdenum powder and the printing characteristics, chemical composition, microstructure, and mechanical properties were compared to pure molybdenum for scan speeds of 100, 200, 400, and 800 mm/s. The addition of silicon carbide improved the consolidation and mechanical properties and the oxygen content was reduced. Two mechanisms of oxygen reduction were identified as responsible for the improvements: oxidation of free carbon and the creation …

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Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite With Quasi-Isotropic Layup, Brian Matthew Pudlo Mar 2023

Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite With Quasi-Isotropic Layup, Brian Matthew Pudlo

Theses and Dissertations

Carbon nanotubes (CNTs) exhibit outstanding mechanical, electrical, and thermal properties, but are a challenge to effectively implement into macroscopic composites for aerospace applications. This research investigates the mechanical properties and performance of a newly developed hybrid NanoStitch composite, alongside a control polymer matrix composite, at room temperature. Both composite material systems investigated in this work have quasi-isotropic layup. Monotonic tension-tofailure, tension-tension fatigue, and creep tests were performed to characterize the performance of the composites under cyclic and sustained loading. Experimental results obtained for the quasi-isotropic NanoStitch composite were compared to those obtained for the quasi-isotropic control composite. The properties and …

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Influence Of Nano-Sized Sic On The Laser Powder Bed Fusion Of Molybdenum, Nathan E. Ellsworth, Ryan A. Kemnitz, Cayla C. Eckley, Brianna M. Sexton, Cynthia T. Bowers, Joshua R. Machacek, Larry W. Burggraf Sep 2022

Influence Of Nano-Sized Sic On The Laser Powder Bed Fusion Of Molybdenum, Nathan E. Ellsworth, Ryan A. Kemnitz, Cayla C. Eckley, Brianna M. Sexton, Cynthia T. Bowers, Joshua R. Machacek, Larry W. Burggraf

Faculty Publications

Consolidation of pure molybdenum through laser powder bed fusion and other additive manufacturing techniques is complicated by a high melting temperature, thermal conductivity and ductile-to-brittle transition temperature. Nano-sized SiC particles (0.1 wt%) were homogeneously mixed with molybdenum powder and the printing characteristics, chemical composition, microstructure, mechanical properties were compared to pure molybdenum for scan speeds of 100, 200, 400, and 800 mm/s. The addition of SiC improved the optically determined density and flexural strength at 400 mm/s by 92% and 80%, respectively. The oxygen content was reduced by an average of 52% over the four scan speeds analyzed. Two mechanisms …

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Monolithically Integrated Microscale Pressure Sensor On An Optical Fiber Tip, Jeremiah C. Williams, Hengky Chandrahalim May 2022

Monolithically Integrated Microscale Pressure Sensor On An Optical Fiber Tip, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) pressure sensor includes an optical fiber and a three-dimensional microscopic optical enclosure. The three-dimensional microscopic optical enclosure includes tubular side walls having lateral pleated corrugations and attached to a cleaved tip of the optical fiber to receive a light signal. An optically reflecting end wall is distally engaged to the tubular side walls to enclose a trapped quantity of gas that longitudinally positions the optically reflecting end wall in relation to ambient air pressure, changing a distance traveled by a light signal reflected back through the optical fiber.

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Hinged Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim May 2022

Hinged Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of the optical fighter using a two-photon polymerization process on a photosensitive polymer by a three-dimensional micromachining device. The three-dimensional microscopic optical structure having a hinged optical layer pivotally connected to a distal portion of a suspended structure. A reflective layer is deposited on a mirror surface of the hinged optical layer while in an open position. The hinged optical layer is subsequently positioned in the closed position to align the mirror surface to at least partially reflect a light signal back …

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Method Of Making Hinged Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim Mar 2022

Method Of Making Hinged Self-Referencing Fabry–Pérot Cavity Sensors, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A method is provided for fabricating a passive optical sensor on a tip of an optical fiber. The method includes perpendicularly cleaving a tip of an optical fiber and mounting the tip of the optical fiber in a specimen holder of a photosensitive polymer three-dimensional micromachining machine. The method includes forming a three-dimensional microscopic optical structure within the photosensitive polymer that comprises a two cavity Fabry-Perot Interferometer (FPI) having a hinged optical layer that is pivotally coupled to a suspended structure. The method includes removing an uncured portion of the photosensitive polymer using a solvent. The method includes depositing a …

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Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith Dec 2021

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor an optical fiber a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fighter that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

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Method Of Making Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith Oct 2021

Method Of Making Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A method of making passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes forming a three-dimensional microscopic optical structure on a cleaved tip of an optical fiber that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.

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Error Reduction For The Determination Of Transverse Moduli Of Single-Strand Carbon Fibers Via Atomic Force Microscopy, Joshua D. Frey Mar 2021

Error Reduction For The Determination Of Transverse Moduli Of Single-Strand Carbon Fibers Via Atomic Force Microscopy, Joshua D. Frey

Theses and Dissertations

The transverse modulus of single strand carbon fibers is measured using PeakForce Atomic Force Microscopy - Quantitative Nanomechanical Measurement to less than 5 percent error for 11 types of carbon fiber with longitudinal moduli between 924-231 GPA, including export-controlled fibers. Statistical methods are employed to improve the quality of data to exclude outliers within an measurement and within the sample set. A positive linear correlation between the longitudinal and transverse modulus with an R2=0.76 is found. Pitch-based fibers exhibit lower measurement error than PAN-based fibers, while PAN fibers exhibited no apparent modulus correlation when the Pitch fibers are …

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Detection Of Hydroxyl Radicals Using Cerium Oxide/Graphene Oxide Composite On Prussian Blue, Surachet Duanghathaipornsuk, Sushil R. Kanel, Emily F. Haushalter, Jessica Ruetz, Dong-Shik Kim Jun 2020

Detection Of Hydroxyl Radicals Using Cerium Oxide/Graphene Oxide Composite On Prussian Blue, Surachet Duanghathaipornsuk, Sushil R. Kanel, Emily F. Haushalter, Jessica Ruetz, Dong-Shik Kim

Faculty Publications

A composite sensor consisting of two separate inorganic layers of Prussian blue (PB) and a composite of cerium oxide nanoparticles (CeNPs) and graphene oxide (GO), is tested with •OH radicals. The signals from the interaction between the composite layers and •OH radicals are characterized using cyclic voltammetry (CV). The degradation of PB in the presence of H2O2 and •OH radicals is observed and its impact on the sensor efficiency is investigated. The results show that the composite sensor differentiates between the solutions with and without •OH radicals by the increase of electrochemical redox current in the presence …

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Laser Induced Thermal Degradation Of Carbon Fiber-Carbon Nanotube Hybrid Laminates, Joshua A. Key Mar 2020

Laser Induced Thermal Degradation Of Carbon Fiber-Carbon Nanotube Hybrid Laminates, Joshua A. Key

Theses and Dissertations

Recent advancements in fiber laser technology have increased interest in target material interactions and the development of thermal protection layers for tactical laser defense. A significant material of interest is carbon fiber reinforced polymers due to their increased use in aircraft construction. In this work, the thermal response of carbon fiber-carbon nanotube (CNT) hybrid composites exposed to average irradiances of 0.87-6.8 W/cm2 were observed using a FLIR sc6900 thermal camera. The camera had a pixel resolution of 640x512 which resulted in a spatial resolution of 0.394x0.383 mm/pixel for the front and 0.463x0.491 mm/pixel for the back. The hybrid samples …

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Gamma-Ray Radiation Effects In Graphene-Based Transistors With H-Bn Nanometer Film Substrates, E. J. Cazalas, Michael R. Hogsed, S. R. Vangala, Michael R. Snure, John W. Mcclory Nov 2019

Gamma-Ray Radiation Effects In Graphene-Based Transistors With H-Bn Nanometer Film Substrates, E. J. Cazalas, Michael R. Hogsed, S. R. Vangala, Michael R. Snure, John W. Mcclory

Faculty Publications

Radiation effects on graphene field effect transistors (GFETs) with hexagonal boron nitride (h-BN) thin film substrates are investigated using 60Co gamma-ray radiation. This study examines the radiation response using many samples with varying h-BN film thicknesses (1.6 and 20 nm thickness) and graphene channel lengths (5 and 10 μm). These samples were exposed to a total ionizing dose of approximately 1 Mrad(Si). I-V measurements were taken at fixed time intervals between irradiations and postirradiation. Dirac point voltage and current are extracted from the I-V measurements, as well as mobility, Dirac voltage hysteresis, and the total number of GFETs that remain …

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Peptide Nanotube Encapsulated Enzyme Biosensor For Vapor Phase Detection Of Malathion, An Organophosphorus Compound, Christopher W. Edwards, Surachet Duanghathaipornsuk, Mark N. Goltz, Sushil Kanel, Dong-Shik Kim Sep 2019

Peptide Nanotube Encapsulated Enzyme Biosensor For Vapor Phase Detection Of Malathion, An Organophosphorus Compound, Christopher W. Edwards, Surachet Duanghathaipornsuk, Mark N. Goltz, Sushil Kanel, Dong-Shik Kim

Faculty Publications

This study explores the use of a butyrylcholinesterase (BChE)-based, reversible reaction biosensor using screen-printed electrodes (SPEs) having a smaller working surface area than the single-use electrodes previously studied. Previous research demonstrated the prospective application of a single-use biosensor fabricated with an acetylcholinesterase (AChE) enzyme encapsulated in peptide nanotubes (PNTs) and enhanced with horseradish peroxidase (HRP) to detect organophosphorus compounds (OPCs) in aqueous and gas phases. In the current study, potential improvements to the biosensor are investigated. BChE-based biosensors were fabricated using PNTs, HRP, and Nafion in combination to increase the reactive surface area, enhance sensitivity, and maintain enzyme stability. Cyclic …

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Electrochemical Modification Of Granular Activated Carbon And Carbon Nanofibers To Determine Effect On Adsorption, Jose E. Martinez Sanchez Mar 2019

Electrochemical Modification Of Granular Activated Carbon And Carbon Nanofibers To Determine Effect On Adsorption, Jose E. Martinez Sanchez

Theses and Dissertations

Granular activated carbon and carbon nanofiber samples were tested as is and electrochemically modified to determine the effect on adsorption. An electrochemical cell was used to modify the carbon samples. The samples were then used in bench bottle tests with 2,4-dinitrotoluene (DNT), brilliant blue (BB) dye, and methylene blue (MB) dye solutions and sampled over time intervals. An ultraviolet–visible spectrophotometer was used to analyze the results of the bottle bench tests. The results indicated that electrochemically modified coal-based carbons’ adsorption were improved 25% over the adsorption of the as is carbon samples prior to modification. The electrochemical modification increased adsorption …

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Predictive Coupled-Cluster Isomer Orderings For Some SiNCM (M, N ≤ 12) Clusters: A Pragmatic Comparison Between Dft And Complete Basis Limit Coupled-Cluster Benchmarks, Jason N. Byrd, Jesse J. Lutz, Duminda S. Ranasinghe, Yifan Jin, Ajith Perera, Xiaofeng F. Duan, Larry W. Burggraf, John A. Montgomery Jr. Jul 2016

Predictive Coupled-Cluster Isomer Orderings For Some SiNCM (M, N ≤ 12) Clusters: A Pragmatic Comparison Between Dft And Complete Basis Limit Coupled-Cluster Benchmarks, Jason N. Byrd, Jesse J. Lutz, Duminda S. Ranasinghe, Yifan Jin, Ajith Perera, Xiaofeng F. Duan, Larry W. Burggraf, John A. Montgomery Jr.

Faculty Publications

The accurate determination of the preferred Si12C12 isomer is important to guide experimental efforts directed towards synthesizing SiC nano-wires and related polymer structures which are anticipated to be highly efficient exciton materials for opto-electronic devices. In order to definitively identify preferred isomeric structures for silicon carbon nano-clusters, highly accurate geometries, energies and harmonic zero point energies have been computed using coupled-cluster theory with systematic extrapolation to the complete basis limit for set of silicon carbon clusters ranging in size from SiC3 to Si12C12. It is found that post-MBPT(2) correlation energy plays a …

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Thermal Transport Properties Of Dry Spun Carbon Nanotube Sheets, Heath E. Misak, James L. Rutledge, Eric D. Swenson, Shankar Mall Feb 2016

Thermal Transport Properties Of Dry Spun Carbon Nanotube Sheets, Heath E. Misak, James L. Rutledge, Eric D. Swenson, Shankar Mall

Faculty Publications

The thermal properties of carbon nanotube- (CNT-) sheet were explored and compared to copper in this study. The CNT-sheet was made from dry spinning CNTs into a nonwoven sheet. This nonwoven CNT-sheet has anisotropic properties in in-plane and out-of-plane directions. The in-plane direction has much higher thermal conductivity than the out-of-plane direction. The in-plane thermal conductivity was found by thermal flash analysis, and the out-of-plane thermal conductivity was found by a hot disk method. The thermal irradiative properties were examined and compared to thermal transport theory. The CNT-sheet was heated in the vacuum and the temperature was measured with an …

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Electrical And Physical Property Characterization Of Single Walled Carbon Nanotube Ink For Flexible Printed Electronics, Kristian E. Warner Jr. Mar 2015

Electrical And Physical Property Characterization Of Single Walled Carbon Nanotube Ink For Flexible Printed Electronics, Kristian E. Warner Jr.

Theses and Dissertations

This research presents a method of characterizing single-walled carbon nanotube (SWCNT) ink. This research also examines the results of our characterization efforts. First, the process of ink jet printing SWCNT ink onto organic and inorganic substrates is discussed. Next, the tests for measuring sheet resistance, conductance, inductance, adherence, thickness, roll-off, and S-parameters of the ink are described. Results and findings of the research are presented. The SWCNT ink created by Brewer Science © is shown to be an effective material for additive manufacturing using an aerosol jet printer, but not an inkjet printer. The ink is shown to have a …

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Reconfigurable Solid-State Dye-Doped Polymer Ring Resonator Lasers, Hengky Chandrahalim, Xudong Fan Jan 2015

Reconfigurable Solid-State Dye-Doped Polymer Ring Resonator Lasers, Hengky Chandrahalim, Xudong Fan

Faculty Publications

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3′-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G) and 3,3′-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse …

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Functionalization Of Carbon Nanotube Yarn By Acid Treatment, Heath E. Misak, Ramazan Asmatulu, Mat O'Malley, Emil Jurak, Shankar Mall Apr 2014

Functionalization Of Carbon Nanotube Yarn By Acid Treatment, Heath E. Misak, Ramazan Asmatulu, Mat O'Malley, Emil Jurak, Shankar Mall

Faculty Publications

Carbon nanotube (CNT) yarn was functionalized using sulfuric and nitric acid solutions in 3:1 volumetric ratio. Successful functionalization of CNT yarn with carboxyl and hydroxyl groups (e.g., COOH, COO–, OH, etc.) was confirmed by attenuated total reflectance spectroscopy. X-ray diffraction revealed no significant change to the atomic in-plane alignment in the CNTs; however, the coherent length along the diameter was significantly reduced during functionalization. A morphology change of wavy extensions protruding from the surface was observed after the functionalization treatment. The force required to fracture the yarn remained the same after the functionalization process; however, the linear density was increased …

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Carbon Allotrope Dependence On Temperature And Pressure During Thermal Decomposition Of Silicon Carbide, Munson J. Anderson Mar 2014

Carbon Allotrope Dependence On Temperature And Pressure During Thermal Decomposition Of Silicon Carbide, Munson J. Anderson

Theses and Dissertations

Bulk CNT and graphene films form on SiC using a metal-catalyst-free thermal decomposition approach. In this work, the background vacuum pressure and temperature used in the decomposition process are varied to investigate their impact on the type and quality of carbon allotrope formed on the SiC substrate. The carbon nanostructure growth is performed using two approaches, both of which involve intense heating (1400-1700°C) of SiC under moderate vacuum conditions (0.01 - 0.00001 Torr). The first growth method uses a conventional graphite resistance furnace capable of annealing waferscale samples over 1700°C under vacuum. Using this approach, post-growth characterization is performed using …

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Using Inductance As A Tuning Parameter For Rf Meta-Atoms, Derrick Langley, Ronald Coutu Jr., Peter J. Collins Jun 2012

Using Inductance As A Tuning Parameter For Rf Meta-Atoms, Derrick Langley, Ronald Coutu Jr., Peter J. Collins

Faculty Publications

The resonant frequency of metamaterials structured with split ring resonator (SRR) meta-atoms is determined primarily through the capacitance and inductance of the individual meta-atoms. Two designs that vary inductance incrementally were modeled, simulated, fabricated, and tested to investigate the role inductance plays in metamaterial designs. The designs consisted of strategically adding sections to the SRR to increase the inductance, but in a manner that minimized capacitance variations. Each design showed a shift in resonant frequency that was proportional to the length of the added section. As the length of each section was increased, the resonant frequency shifted from 2.78 GHz …

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Field Emission Of Thermally Grown Carbon Nanostructures On Silicon Carbide, Jonathon M. Campbell Mar 2012

Field Emission Of Thermally Grown Carbon Nanostructures On Silicon Carbide, Jonathon M. Campbell

Theses and Dissertations

CNTs are known to be excellent field emitter due to their unique physical and electrical properties. Because of their semi-metallic nature, CNT do not suffer the thermal runaway found in metallic emitters, and their near one-dimension shape make them an ideal emission sources. CNTs growth by thermal decomposition of silicon carbide does not utilize a catalyst, therefore relatively defect free. One drawback to this method, however is that the CNT grow in a very dense carpet. This very dense CNT carpet comes under the affect of field emission screening effects which dampen the field emission. In this thesis, silicon carbide …

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Using Nanotechnology To Detect Nerve Agents, Mark N. Goltz, Dong-Shik Kim, Leeann Racz Jul 2011

Using Nanotechnology To Detect Nerve Agents, Mark N. Goltz, Dong-Shik Kim, Leeann Racz

Faculty Publications

Nanotechnology has opened a wide range of opportunities having potential impacts in areas as diverse as medicine and consumer products. In collaboration with researchers at the University of Toledo UT, Air Force Institute of Technology AFIT scientists are exploring the possibility of using a nanoscale organic matrix to detect organophosphate OP nerve agents. Current techniques for detecting OP compounds are expensive and time consuming. Developing a nanoscale organic matrix sensor would allow for direct, real-time sensing under field conditions. This article describes the science behind such a sensor and its possible applications. High-performance sensors are needed to protect Soldiers and …

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Providing A Theoretical Basis For Nanotoxicity Risk Analysis Departing From Traditional Physiologically-Based Pharmacokinetic (Pbpk) Modeling, Dirk P. Yamamoto Sep 2010

Providing A Theoretical Basis For Nanotoxicity Risk Analysis Departing From Traditional Physiologically-Based Pharmacokinetic (Pbpk) Modeling, Dirk P. Yamamoto

Theses and Dissertations

The same novel properties of engineered nanoparticles that make them attractive may also present unique exposure risks. But, the traditional physiologically-based pharmacokinetic (PBPK) modeling assumption of instantaneous equilibration likely does not apply to nanoparticles. This simulation-based research begins with development of a model that includes diffusion, active transport, and carrier mediated transport. An eigenvalue analysis methodology was developed to examine model behavior to focus future research. Simulations using the physicochemical properties of size, shape, surface coating, and surface charge were performed and an equation was determined which estimates area under the curve for arterial blood concentration, which is a surrogate …

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Fatigue Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Javier Rodriguez Mar 2009

Fatigue Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Javier Rodriguez

Theses and Dissertations

Existing nanocomposite materials used for satellite applications don't offer the required conductivity and electromagnetic shielding protection, requiring metal shields in order to survive in space. The AFRL Materials and Manufacturing Directorate in conjunction with the private sector have developed a material that promises to blend the attributes of nanocomposites and metal materials. The M55J/RS3 material consists of carbon fibers combined with a polyisocyanate matrix, in which Nickel nanostrandsTM are added. The research effort investigated the changes in the EMI and ESD of the material after being subjected to cyclic loads. Four configurations of a symmetric layup with fibers oriented …

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Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler Mar 2009

Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler

Theses and Dissertations

This research studies the growth of carbon nanotubes (CNT) from a nickel catalyst to be used on a field emission device. This thesis can be divided into three sections: the construction of a vacuum chamber for field emission testing, the design and fabrication of a triode structure to enable improved electron emission, and the pretreatment and growth of CNTs. To experimentally test the field emission of CNTs, a vacuum chamber must attain a vacuum of at least 10-5 torr. Our vacuum chamber designed and built achieved a maximum, final pressure of 10-8 torr. A triode structure was designed …

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Electrostatic Discharge Properties Of Irradiated Nanocomposites, Joshua D. Mcgary Mar 2009

Electrostatic Discharge Properties Of Irradiated Nanocomposites, Joshua D. Mcgary

Theses and Dissertations

Modernization in space systems requires employment of new light-weight, high performance composite materials that reduce bulk weight and increase structural integrity. This thesis explored the behavior of one such material prior to and following a 35-year simulated space radiation life-cycle. Select electrical properties of nickel nanostrandTM-carbon composites in seven configurations were characterized prior to electron irradiation via surface and bulk resistivity measurements and contact electrostatic discharge (ESD) measurements. Following irradiation at a fluence of 1016 e-/cm2 at an average energy of 500 keV, measurements were repeated and compared against pre-irradiation data. Configuration D is …

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Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Benjamin T. Harder Jun 2008

Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Benjamin T. Harder

Theses and Dissertations

The United States military is exploring the use of nanocomposite materials for satellite structural applications. Current composite spacecraft structures are nonconductive and must have expensive shielding materials applied in order to protect the spacecraft from catastrophic damage that can be caused by electromagnetic interference (EMI) and/or electrostatic discharge (ESD) which are characteristics of the space environment. Conductive nanocomposites are being developed for spacecraft structures that will provide ESD and EMI shielding protection without the need for expensive secondary shielding materials. This thesis studied one such material consisting of M55J/RS-3 composite combined with nickel nanostrands™. Four different configurations were tested for …

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Nano-Mechanical Properties Of Heat Inactivated Bacillus Anthracis And Bacillus Thuringiensis Spores, Jessica L. Poindexter Mar 2008

Nano-Mechanical Properties Of Heat Inactivated Bacillus Anthracis And Bacillus Thuringiensis Spores, Jessica L. Poindexter

Theses and Dissertations

B. thuringiensis spores must have similar properties to B. anthracis spores to be a good simulant in counter-proliferation studies. In particular, they must behave in a similar way when exposed to high temperatures for short periods of time as would be caused by an explosion. This research project compares surface elasticities for four different spore sample types, B. anthracis spores, heat inactivated B. anthracis spores, B. thuringiensis spores, and heat inactivated B. thuringiensis spores. Heat inactivated spores were exposed to a temperature just high enough that no spores were observed to germinate. Elasticity values for the spore surfaces were determined …

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