Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- TEM (2)
- Agglomeration (1)
- Amorphous (1)
- Aps (1)
- Band Gap (1)
-
- Bulk metallic glass (1)
- CIGS (1)
- CIGSeS (1)
- Carbon (1)
- Carbon nanotube (1)
- Cell culture (1)
- Cell patterning (1)
- Ceramics (1)
- Ceria (1)
- Cerium Oxide (1)
- Characterization (1)
- CoNiCrAlY (1)
- Composite (1)
- Conductivity (1)
- Conjugated polymer (1)
- DLTS (1)
- Degradation (1)
- Derived (1)
- Diffusion (1)
- Durability (1)
- Effect of Nb and carbon. (1)
- Epoxy (1)
- Fuel cell (1)
- Glass forming ability (1)
- Gold nanoparticles (1)
Articles 1 - 13 of 13
Full-Text Articles in Engineering
Quantitative Thickness Mapping In High-Angle Annular Dark-Field (Haadf) Scanning Transmission Electron Microscopy (Stem), Haritha Nukala
Quantitative Thickness Mapping In High-Angle Annular Dark-Field (Haadf) Scanning Transmission Electron Microscopy (Stem), Haritha Nukala
Electronic Theses and Dissertations
Only a few methods are currently available for the measurement of sample thicknesses in Transmission Electron Microscopy (TEM). These methods, Convergent-Beam Electron Diffraction (CBED) and thickness mapping in Energy-Filtered TEM (EFTEM), are either elaborate or complex. In this present work, I have investigated and come up with a simple straight-forward method to measure the local thickness of a TEM sample with the atomic number (Z-contrast) imaging using High-Angle Annular Dark Field (HAADF) Scanning Transmission Electron Microscopy (STEM). HAADF STEM shows atomic number contrast for high scattering angles of the electrons, owing to predominant electron scattering at the potential of the …
Effects Of Internal Oxidation On Thermo-Mechanical Properties Of Atmospheric Plasma Sprayed Conicraly Coatings, Travis Patterson
Effects Of Internal Oxidation On Thermo-Mechanical Properties Of Atmospheric Plasma Sprayed Conicraly Coatings, Travis Patterson
Electronic Theses and Dissertations
Thermal barrier coatings (TBC) with MCrAlY (M=Co and/or Ni) bond coats have been widely used in hot sections of gas turbines to protect underlying superalloys from high temperatures, oxidation, and hot corrosion. Deposition of MCrAlY bond coats using atmospheric plasma spray (APS), as oppose to conventionally employed vacuum/low-pressure plasma spray and high velocity oxy-fuel deposition, allows greater flexibility in ability to coat economically and rapidly for parts with complex geometry including internal surfaces. There were three objectives of this study. First, relationships between APS spray parameters and coating microstructure was examined to determine optimum spray parameters to deposit APS CoNiCrAlY …
Prevention Of Environmentally Induced Degradation In Carbon/Epoxy Composite Material Via Implementation Of A Polymer Based Coati, Bradford Tipton
Prevention Of Environmentally Induced Degradation In Carbon/Epoxy Composite Material Via Implementation Of A Polymer Based Coati, Bradford Tipton
Electronic Theses and Dissertations
As the use of fiber reinforced plastics increases in such industries as aerospace, wind energy, and sporting goods, factors effecting long-term durability, such as environmental exposure, are of increasing interest. The primary objectives of this study were to examine the effects of extensive environmental exposure (specifically UV radiation and moisture) on carbon/epoxy composite laminate structures and to determine the relative effectiveness of polymer-based coatings at mitigating degradation incurred due to such exposure. Carbon/epoxy composite specimens, both coated and uncoated, were subjected to accelerated weathering in which prolonged outdoor exposure was simulated by controlling the radiation wavelength (in the UV region), …
Probing And Tuning The Size, Morphology, Chemistry And Structure Of Nanoscale Cerium Oxide, Satyanarayana Kuchibhatla
Probing And Tuning The Size, Morphology, Chemistry And Structure Of Nanoscale Cerium Oxide, Satyanarayana Kuchibhatla
Electronic Theses and Dissertations
Cerium oxide (ceria)-based materials in the nanoscale regime are of significant fundamental and technological interest. Nanoceria in pure and doped forms has current and potential use in solid oxide fuel cells, catalysis, UV- screening, chemical mechanical planarization, oxygen sensors, and bio-medical applications. The characteristic feature of Ce to switch between the +3 and + 4 oxidation states renders oxygen buffering capability to ceria. The ease of this transformation was expected to be enhanced in the nanoceria. In most the practical scenarios, it is necessary to have a stable suspension of ceria nanoparticles (CNPs) over longer periods of time. However, the …
Amorphous Phase Formation In Mechanically Alloyed Fe-Based Systems., Satyajeet Sharma
Amorphous Phase Formation In Mechanically Alloyed Fe-Based Systems., Satyajeet Sharma
Electronic Theses and Dissertations
Bulk metallic glasses have interesting combination of physical, chemical, mechanical, and magnetic properties which make them attractive for a variety of applications. Consequently there has been a lot of interest in understanding the structure and properties of these materials. More varied applications can be sought if one understands the reasons for glass formation and the methods to control them. The glass-forming ability (GFA) of alloys can be substantially increased by a proper selection of alloying elements and the chemical composition of the alloy. High GFA will enable in obtaining large section thickness of amorphous alloys. Ability to produce glassy alloys …
N Multilayer Thin Film Reactions To Form L10 Fept And Exchange Spring Magnets, Bo Yao
N Multilayer Thin Film Reactions To Form L10 Fept And Exchange Spring Magnets, Bo Yao
Electronic Theses and Dissertations
FePt films with the L10 phase have potential applications for magnetic recording and permanent magnets due to its high magnetocrystalline anisotropy energy density. Heat treatment of n multilayer films is one approach to form the L10 FePt phase through a solid state reaction. This thesis has studied the diffusion and reaction of n multilayer films to form the L10 FePt phase and has used this understanding to construct exchange spring magnets. The process-structure-property relations of n multilayer films were systematically examined. The transmission electron microscopy (TEM) study of the annealed multilayers indicates that the Pt layer grows at the expense …
Effect Of Composition, Morphology And Semiconducting Properties On The Efficiency Of Cuin1-Xgaxse2-Ysy Thin-Film Solar Cells Pre, Sachin Kulkarni
Effect Of Composition, Morphology And Semiconducting Properties On The Efficiency Of Cuin1-Xgaxse2-Ysy Thin-Film Solar Cells Pre, Sachin Kulkarni
Electronic Theses and Dissertations
A rapid thermal processing (RTP) reactor for the preparation of graded CuIn1-xGaxSe2-ySy (CIGSeS) thin-film solar cells has been designed, assembled and is being used at the Photovoltaic Materials Laboratory of the Florida Solar Energy Center. CIGSeS films having the optimum composition, morphology, and semiconducting properties were prepared using RTP. Initially films having various Cu/(In+Ga) ratios were prepared. In the next step selenium incorporation in these films was optimized, followed by sulfur incorporation in the surface to increase the bandgap at the surface. The compositional gradient of sulfur was fine-tuned so as to increase the conversion efficiency. Materials properties of these …
Laser Enhanced Doping For Silicon Carbide White Light Emitting Diodes, Sachin Bet
Laser Enhanced Doping For Silicon Carbide White Light Emitting Diodes, Sachin Bet
Electronic Theses and Dissertations
This work establishes a solid foundation for the use of indirect band gap semiconductors for light emitting application and presents the work on development of white light emitting diodes (LEDs) in silicon carbide (SiC). Novel laser doping has been utilized to fabricate white light emitting diodes in 6H-SiC (n-type N) and 4H-SiC (p-type Al) wafers. The emission of different colors to ultimately generate white light is tailored on the basis of donor acceptor pair (DAP) recombination mechanism for luminescence. A Q-switched Nd:YAG pulse laser (1064 nm wavelength) was used to carry out the doping experiments. The p and n regions …
Production Of Bulk Ceramic Shapes From Polymer Derived Ceramics, Arnold Hill
Production Of Bulk Ceramic Shapes From Polymer Derived Ceramics, Arnold Hill
Electronic Theses and Dissertations
A method has been developed to produce bulk ceramic components from a class of ceramics known as polymer derived ceramics. In the past polymer derived ceramics have been limited to thin film applications or in the fabrication of MEMS devices. The reason being that when the polymer is into a ceramic, large quantities of gas are generated which produce internal pressure that fractures the ceramic components. The method developed here solves that issue by casting into the polymer a 3 dimensional network of polymer fibers in the form of a foam which, during pyrolysis, burns out and leaves a network …
Preparation And Characterisation Of Stabilized Nafion/Phosphotungstic Acid Composite Membranes For Proton Exchange Membrane Fuel Cell (Pemfc) Automobile Engines, Rohit Agarwal
Electronic Theses and Dissertations
Membrane durability is one of the limiting factors for proton exchange membrane fuel cell (PEMFC) commercialisation by limiting the lifetime of the membrane via electrochemical / mechanical / thermal degradation. Lower internal humidity in the membrane at high temperature ( > 100 °C) and low relative humidity (25-50 %RH) operating conditions leads to increased resistance, lowering of performance and higher degradation rate. One of the promising candidates is composite proton exchange membranes (CPEMs) which have heteropoly acid (HPA) e.g. Phosphotungstic acid (PTA) doped throughout the Nafion® matrix. HPA is primarily responsible for carrying intrinsic water which reduces the external water dependence. …
Application Of Polyelectrolyte Multilayers For Photolithographic Patterning Of Diverse Mammalian Cell Types In Serum Free Medium, Vipra Dhir
Electronic Theses and Dissertations
Integration of living cells with novel microdevices requires the development of innovative technologies for manipulating cells. Chemical surface patterning has been proven as an effective method to control the attachment and growth of diverse cell populations. Patterning polyelectrolyte multilayers through the combination of layer-by-layer self-assembly technique and photolithography offers a simple, versatile and silicon compatible approach that overcomes chemical surface patterning limitations, such as short-term stability and low protein adsorption resistance. In this study, direct photolithographic patterning of PAA/PAAm and PAA/PAH polyelectrolyte multilayers was developed to pattern mammalian neuronal, skeletal and cardiac muscle cells. For all studied cell types, PAA/PAAm …
Synthesis And Characterization Of Polymer-Derived Porous Sicn Ceramics, Yun Wei
Synthesis And Characterization Of Polymer-Derived Porous Sicn Ceramics, Yun Wei
Electronic Theses and Dissertations
The synthesis and characterization of porous SiCN ceramics produced by the method of polymer-derived ceramics were studied in this work. The polymer-to-ceramic conversion technique is a novel revolution in the methods for fabricating porous materials with controlled morphologies and tailored properties. The porous SiCN ceramics can be successfully prepared from thermal decomposition of polymeric precursors (polysilazane) and the pore former (polyvinyl alcohol (PVA)). The fabrication procedures involved the mixing of the pre-ceramic precursor with appropriate concentration of the PVA, curing, pyrolysis and subsequent PVA removal, leaving pores in the ceramic matrix. The material obtained revealed a homogeneous amorphous microstructure consisting …
Development And Application Study Of Nanoscale Thin Film Materials And Polymer Nanocomposites, Hui Chen
Development And Application Study Of Nanoscale Thin Film Materials And Polymer Nanocomposites, Hui Chen
Electronic Theses and Dissertations
This dissertation demonstrated that the manipulation of substances at the molecular or nanometer level can lead to the discovery and development of new materials with interesting properties and important applications. Chapter 1 describes the development of a nanoscale molecular thin film material for corrosion protection. By using a self-assembled monolayer film with a thickness of only about 1 nanometer as a linkage, a covalent bonding was achieved between a polyurethane top coating and an aluminum alloy substrate. This covalent bonding between polymer top coating and the aluminum alloy substrate significantly improved the corrosion resistance of the substrate. Chapter 2 and …