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Articles 181 - 210 of 220

Full-Text Articles in Materials Science and Engineering

Plasma Processing For Retention Of Nanostructures, Viswanathan Venkatachalapathy Jan 2007

Plasma Processing For Retention Of Nanostructures, Viswanathan Venkatachalapathy

Electronic Theses and Dissertations

Plasma spray processing is a technique that is used extensively in thermal barrier coatings on gas and steam turbine components, biomedical implants and automotive components. Many processing parameters are involved to achieve a coating with certain functionality. The coating could be required to function as thermal barrier, wear resistant, corrosion resistant or a high temperature oxidation resistant coating. Various parameters, such as, nozzle and electrode design, powder feeding system, spray distances, substrate temperature and roughness, plasma gas flow rates and others can greatly alter the coating quality and resulting performance. Feedstock (powder or solution precursor) composition and morphology are some …

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Tunable Nanostructure Anti-Reflective Coatings, Erik Brinley Jan 2007

Tunable Nanostructure Anti-Reflective Coatings, Erik Brinley

Electronic Theses and Dissertations

Research was conducted on broadband, anti-reflective coatings for fused silica and chalcogenide substrates in the infrared region of light. Using chemical preparation to create nano-porous through nano-particle based sol-gel solutions, the alteration of optical properties including refractive index and optical thickness was conducted. The nano-particles can modify the coating surface to allow only zero-order diffracted wave propagation reducing scattering while a partially graded profile of refractive index due surface evaporation lessened the precise phase relations of typical homogeneous coatings. My study of silica and titania sol-gel, and hybrid mixtures of the two were used to obtain the optical properties of …

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Self-Assembled Lipid Tubules: Structures, Mechanical Properties, And Applications., Yue Zhao Jan 2007

Self-Assembled Lipid Tubules: Structures, Mechanical Properties, And Applications., Yue Zhao

Electronic Theses and Dissertations

Self-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been predicted by current theories, and therefore provide valuable supporting evidences for self-assembly mechanisms of chiral molecules. Two novel methods are developed for studying the axial and radial deformations of DC8,9PC lipid tubules. Mechanical properties of DC8,9PC tubules …

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Zinc Cadmium Sulphide And Zinc Sulphide As Alternative Heterojunction Partners For Cigs2 Solar Cells, Bhaskar Kumar Jan 2007

Zinc Cadmium Sulphide And Zinc Sulphide As Alternative Heterojunction Partners For Cigs2 Solar Cells, Bhaskar Kumar

Electronic Theses and Dissertations

Devices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS devices, which results in higher interface dominated recombination. Moreover, it has been predicted that optimum band offsets for higher efficiency solar cells may be achieved for cells with …

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Redistribution Of Manganese Ion Implanted In Silicon, Arun Kumar Shunmugavelu Jan 2007

Redistribution Of Manganese Ion Implanted In Silicon, Arun Kumar Shunmugavelu

Electronic Theses and Dissertations

Ion implantation and the subsequent redistribution of manganese atoms in Czochralski Silicon (Cz-Si) and Floating Zone Silicon (Fz-Si) due to thermal annealing between 300 C and 1000 C is studied using Secondary Ion Mass Spectroscopy. The samples ion implanted at 340 C showed multiple peak formation above 900 C. This was not observed for the samples ion implanted at room temperature. Cz-Si and Fz-Si showed similar redistribution profiles.

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Microwave Synthesis Of Nanocrystalline Hydroxy Apatite And Comparison Of Its Biomechanical Properties With Tio2 Structures, Saurabh Verma Jan 2007

Microwave Synthesis Of Nanocrystalline Hydroxy Apatite And Comparison Of Its Biomechanical Properties With Tio2 Structures, Saurabh Verma

Electronic Theses and Dissertations

Nanocrystalline hydroxyapatite (HAp) powder of size 10-20 nm was synthesized applying microwave radiation using calcium nitrate tetrahydrate and sodium phosphate dibasic anhydrous as the starting materials. Microwave power of 600 W and Ca/P ratio of 1.66 in the starting chemicals served as the major factors in the synthesis of nanocrystalline HAp powder. Phase composition and evolution were studied using X-ray diffraction (XRD) technique. Morphology, agglomeration and particle-size of the synthesized powder were studied using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Energy Dispersive Spectrum (EDS) was used to determine the elemental composition of the powder. Thermal properties …

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Film Growth Of Novel Frequency Agile Complex-Oxide Piezoelectric Material, Bindu Sreeramakavacham Jan 2007

Film Growth Of Novel Frequency Agile Complex-Oxide Piezoelectric Material, Bindu Sreeramakavacham

Electronic Theses and Dissertations

Piezoelectric materials are well known for their applications in surface (SAW) and bulk acoustic wave (BAW) devices such as oscillators, resonators and sensors. Quartz has been the main material used in such applications. Ternary calcium gallium germanate (CGG) structure-type materials, so-called langasites, recently emerged as very promising because of their piezoelectric properties superior to quartz. This thesis discusses the growth of langasite-type La3Ga5.5Ta0.5O14 (LGT) films by liquid phase epitaxy (LPE) technique and their chemical and structural characterization. In addition, the different techniques suitable for the growth of LGT are discussed and compared. To adjust the materials properties for given applications, …

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Polymer-Derived Si-Al-C-N Ceramics:Oxidation, Hot-Corrosion, And Structural Evolution, Yiguang Wang Jan 2006

Polymer-Derived Si-Al-C-N Ceramics:Oxidation, Hot-Corrosion, And Structural Evolution, Yiguang Wang

Electronic Theses and Dissertations

Polymer-derived ceramics are a new class of materials synthesized by thermal decomposition of polymer precursors. Previous studies have shown that the materials exhibit excellent thermo-mechanical properties and can be stable at temperatures up to 2000oC. Furthermore, the novel polymer-to-ceramics process enables the manipulation of the ceramic structures at the atomic/nano level by designing the chemistry of polymer precursors and controlling the pyrolysis conditions, thereby, the properties of ceramics. In this dissertation, oxidation/hot-corrosion behavior and the structural evolution of Si-Al-C-N ceramics have been studied. The structural evolution and crystallization behavior of the SiCN and SiAlCN ceramics are investigated using FT-IR, XRD, …

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Polymer-Derived Ceramics: Electronic Properties And Application, Weixing Xu Jan 2006

Polymer-Derived Ceramics: Electronic Properties And Application, Weixing Xu

Electronic Theses and Dissertations

In this work, we studied the electronic behavior of polymer-derived ceramics (PDCs) and applied them for the synthesis of carbon nanotube reinforced ceramic nanocomposites and ceramic MEMS (Micro-Electro-Mechanical Systems) structures. Polymer-derived SiCN ceramics were synthesized by pyrolysis of a liquid polyureasilazane with dicumyl peroxide as thermal initiator. The structural evolution during pyrolysis and post-annealing was studied using FTIR, solid state NMR and Raman. The results revealed that the resultant ceramics consisted of SiCxNx-4 as major building units. These units were connected with each other through C-C/C=C bonds or by shearing N/C. The amount of sp2 free carbon strongly depends on …

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Laser Metallization And Doping For Silicon Carbide Diode Fabrication And Endotaxy, Zhaoxu Tian Jan 2006

Laser Metallization And Doping For Silicon Carbide Diode Fabrication And Endotaxy, Zhaoxu Tian

Electronic Theses and Dissertations

Silicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal deposition and dope in silicon carbide without high temperature annealing, as an alternative to the conventional ion implantation, and find applications of this laser direct write metallization and doping technique …

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Development Of Thermally Processed Nanocomposites With Controlled Surfaces, Petya Georgieva Jan 2006

Development Of Thermally Processed Nanocomposites With Controlled Surfaces, Petya Georgieva

Electronic Theses and Dissertations

The ever increasing need for technology development requires the integration of inexpensive, light weight and high strength materials which are able to meet the high standards and specifications for various engineering applications. The intention of this work is to show that the suitable material selection and the utilization of plasma spray processing can be of potential interest to a large number of industrial, biomedical and everyday life applications. This research demonstrates also that plasma processing is a promising engineering tool for multifunctional coatings and near-net-shape manufacturing. Further, the theoretical and experimental results are combined in order to explain the mechanisms …

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Magnetic Properties Of Sputter Deposited Fe-Based Amorphous Thin Films For Resonator Application, Chaitali China Jan 2006

Magnetic Properties Of Sputter Deposited Fe-Based Amorphous Thin Films For Resonator Application, Chaitali China

Electronic Theses and Dissertations

In this study we investigate the magnetic properties of Fe-based amorphous thin films. Fe1-x-y-zBxSiyCz, Fe80-xNixB20, Fe80-xMnxB20, and Fe73-xMnxB27 films were deposited on silicon and glass substrates in a DC and RF magnetron sputtering system. Inductive magnetic measurements were performed to investigate the magnetic properties, including induced anisotropy and magnetostriction, of the as-deposited and annealed films using an M-H Looper. The chemical composition of the films was characterized using secondary ion mass spectroscopy (SIMS). The physical thickness of the films was determined by use of a stylus profilometer. The M-H Looper studies indicated that the induced anisotropy (Hk) depends strongly on …

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Fundamental Aspects Of Regenerative Cerium Oxide Nanoparticles And Their Applications In Nanobiotechnology, Swanand Patil Jan 2006

Fundamental Aspects Of Regenerative Cerium Oxide Nanoparticles And Their Applications In Nanobiotechnology, Swanand Patil

Electronic Theses and Dissertations

Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of …

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Synthesis, Processing And Characterization Of Nanocrystalline Titanium Dioxide, Shipeng Qiu Jan 2006

Synthesis, Processing And Characterization Of Nanocrystalline Titanium Dioxide, Shipeng Qiu

Electronic Theses and Dissertations

Titanium dioxide (TiO2), one of the basic ceramic materials, has found a variety of applications in industry and in our daily life. It has been shown that particle size reduction in this system, especially to nano regime, has the great potential to offer remarkable improvement in physical, mechanical, optical, biological and electrical properties. This thesis reports on the synthesis and characterization of the nanocrystalline TiO2 ceramic in details. The study selected a simple sol-gel synthesis process, which can be easily controlled and reproduced. Titanium tetraisopropoxide, isopropanol and deionized water were used as starting materials. By careful control of relative proportion …

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Preparation Of Efficient Cuin1-Xgaxse2-Ysy/Cds Thin-Film Solar Cells By Optimizing The Molybdenum Back Contact And Using Diethylselenide As Selenium Precursor, Ankur Kadam Jan 2006

Preparation Of Efficient Cuin1-Xgaxse2-Ysy/Cds Thin-Film Solar Cells By Optimizing The Molybdenum Back Contact And Using Diethylselenide As Selenium Precursor, Ankur Kadam

Electronic Theses and Dissertations

High efficiency CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells were prepared by optimizing the Mo back contact layer and optimizing the parameters for preparing CIGSS absorber layer using diethylselenide as selenium source. The Mo film was sputter deposited on 2.5 cm x 10 cm soda-lime glass using DC magnetron sputtering for studying the adhesion and chemical reactivity with selenium and sulfur containing gas at maximum film growth temperature. Mo being a refractory material develops stresses, nature of which depends on the deposition power and argon pressure. It was found that the deposition sequence with two tensile stressed layers deposited at 200W and …

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A Methodology For Instrumented Indentation Studies Of Deformation In Bulk Metallic Glasses, Subhaashree Sridharan Jan 2006

A Methodology For Instrumented Indentation Studies Of Deformation In Bulk Metallic Glasses, Subhaashree Sridharan

Electronic Theses and Dissertations

Bulk Metallic Glasses (BMGs), also known as amorphous metals, are of considerable scientific and commercial interest due to their random or chaotic structure. Given their potential use as engineering materials, there is a concomitant need to establish their mechanical properties. However, BMGs are not conveniently available in sufficient volumes (especially experimental and combinatorial compositions), making property determination via conventional tensile or compression testing problematic. Instrumented indentation is ideally suited for this purpose because the testing requires only small sampling volumes and can probe multiaxial deformation characteristics at various length scales. In this technique, conducted generally on a sub-micron regime, the …

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Characterization Of Microstructural And Chemical Features In Cu-In-Ga-Se-S-Based Thin-Film Solar Cells, Ankush Halbe Jan 2006

Characterization Of Microstructural And Chemical Features In Cu-In-Ga-Se-S-Based Thin-Film Solar Cells, Ankush Halbe

Electronic Theses and Dissertations

Thin-film solar cells are potentially low-cost devices to convert sunlight into electricity. Improvements in the conversion efficiencies of these cells reduce material utilization cost and make it commercially viable. Solar cells from the Thin-Film Physics Group, ETH Zurich, Switzerland and the Florida Solar Energy Center (FSEC), UCF were characterized for defects and other microstructural features within the thin-film structure and at the interfaces using transmission electron microscopy (TEM). The present thesis aims to provide a feedback to these groups on their deposition processes to understand the correlations between processing, resulting microstructures, and the conversion efficiencies of these devices. Also, an …

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Density-Functional Theory Applied To Problems In Catalysis And Electrochemistry, Santosh Kumar Jan 2006

Density-Functional Theory Applied To Problems In Catalysis And Electrochemistry, Santosh Kumar

Electronic Theses and Dissertations

We study the structure and energetics of water molecules adsorbed at ceria (111) surfaces below one monolayer coverage using density-functional theory. The results of this study provide a theoretical framework for interpreting recent experimental results on the redox properties of water at ceria (111) surfaces. In particular, we have computed the structure and energetics of various absorption geometries at stoichiometric ceria (111) surface. In contrast to experiment results, we do not find a strong coverage dependence of the adsorption energy. For the case of reduced surface, our results show that it may not be energetically favorable for water to oxidize …

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Alumina-Aluminum Titanate-Titania Nanocomposite: Synthesis, Sintering Studies, Assessment Of Bioactivity And Its Mechanical And Electrical Properties, Vikas Somani Jan 2006

Alumina-Aluminum Titanate-Titania Nanocomposite: Synthesis, Sintering Studies, Assessment Of Bioactivity And Its Mechanical And Electrical Properties, Vikas Somani

Electronic Theses and Dissertations

This thesis reports the development, synthesis and characterization of a ceramic-ceramic nanocomposite system for its possible application as structural and electronic biomaterial in the biomedical industry. The study selected and synthesized alumina-aluminum titanate-titania (Al2O3-Al2TiO5-TiO2) nanoceramic composite using a simple Sol-Gel technique, which can be easily reproduced. Aluminum propoxide and titanium propoxide were used as precursor chemicals. Propanol and 2- methoxy ethanol were used as solvent and stabilizer, respectively. Thermal analyses were performed for a systematic understanding of phase evolution from the synthesized gel. X-Ray diffraction technique was used to confirm the phase evolution, phase purity, crystallite size and crystal structure(s) …

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Evolution Of Lamellar Structures In Al-Ag Alloys, Sephalika Senapati Jan 2005

Evolution Of Lamellar Structures In Al-Ag Alloys, Sephalika Senapati

Electronic Theses and Dissertations

In the present study, the formation and the evolution of lamellar structures in different Al-Ag alloys were investigated by transmission electron microscopy (TEM). Plates of the hexagonal [gamma] phase form semi-coherently on the {111} planes of the face centered cubic lattice of the alloy after the formation of Guinier-Preston zones. Guinier-Preston zones are metastable coherent preprecipitates which are silver rich in the aluminum-rich Al-Ag alloys. The decomposition of aluminum rich Al-Ag alloys, particularly the sequence of the later stages of precipitate formation was studied. With scanning electron microscopy and high-resolution transmission electron microscopy the development of the [gamma] phase was …

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Diffraction Studies Of Deformation In Shape Memory Alloys And Selected Engineering Components, Chandrasen Rathod Jan 2005

Diffraction Studies Of Deformation In Shape Memory Alloys And Selected Engineering Components, Chandrasen Rathod

Electronic Theses and Dissertations

Deformation phenomena in shape memory alloys involve stress-, temperature-induced phase transformations and crystallographic variant conversion or reorientation, equivalent to a twinning operation. In near equiatomic NiTi, Ti rich compositions can exist near room temperature as a monoclinic B19' martensitic phase, which when deformed undergoes twinning resulting in strains as large as 8%. Upon heating, the martensite transforms to a cubic B2 austenitic phase, thereby recovering the strain and exhibiting the shape memory effect. Ni rich compositions on the other hand can exist near room temperature in the austenitic phase and undergo a reversible martensitic transformation on application of stress. Associated …

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The Effect Of Colloidal Stability On The Heat Transfer Characteristics Of Nanosilica Dispersed Fluids, Manoj Venkataraman Jan 2005

The Effect Of Colloidal Stability On The Heat Transfer Characteristics Of Nanosilica Dispersed Fluids, Manoj Venkataraman

Electronic Theses and Dissertations

Addition of nano particles to cooling fluids has shown marked improvement in the heat transfer capabilities. Nanofluids, liquids that contain dispersed nanoparticles, are an emerging class of fluids that have great potential in many applications. There is a need to understand the fundamental behavior of nano dispersed particles with respect to their agglomeration characteristics and how it relates to the heat transfer capability. Such an understanding is important for the development and commercialization of nanofluids. In this work, the stability of nano particles was studied by measuring the zeta potential of colloidal particles, particle concentration and size. Two different sizes …

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Synthesis And Characterization Of Nanocrystalline Hydroxyapatite Powder; And The Effects Of Oxide-Based Sintering Additives On Tricalcium Phosphate, Himesh A. Bhatt Jan 2005

Synthesis And Characterization Of Nanocrystalline Hydroxyapatite Powder; And The Effects Of Oxide-Based Sintering Additives On Tricalcium Phosphate, Himesh A. Bhatt

Electronic Theses and Dissertations

Calcium phosphate (CP) materials have been used extensively for bone replacement and augmentation due to their similarity to the mineral component of bone. In addition to being non-toxic, they are biocompatible, not recognized as foreign materials in vivo, and most importantly, exhibit osteoconductive behavior, being able to help in bone formation during healing. CPs form an intimate physicochemical bond with the host tissue, termed osseointegration. However the main limitation of calcium phosphates is their inherent brittle nature and poor mechanical performance under complex stress states. As a result, these materials have been used clinically only in non-load-bearing applications, primarily as …

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Microstructural And Mechanical Characterization Of Al-Al2o3 Nanocomposites Synthesized By High-Energy Milling, Balaji Prabhu Jan 2005

Microstructural And Mechanical Characterization Of Al-Al2o3 Nanocomposites Synthesized By High-Energy Milling, Balaji Prabhu

Electronic Theses and Dissertations

The twin objectives of the investigation were (i) to synthesize Al/Al2O3 metal matrix composites (MMCs) with uniform distribution of the Al2O3 reinforcement in the Al matrix and (ii) to evaluate the effect of volume fraction and size of the reinforcement on the mechanical behavior of MMCs. This was achieved by successful synthesis of Al-Al2O3 MMCs with volume fractions of 5, 10, 20, 30, and 50%, and particle sizes of 50 nm, 150 nm, and 5 µm of Al2O3 synthesized from blended component powders by a high-energy milling technique. A uniform distribution of the Al2O3 reinforcement in the Al matrix was …

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Nondestructive Evaluation Of Thermal Barrier Coatings With Thermal Wave Imaging And Photostimulated Luminescence Spectroscopy, Barbara Franke Jan 2005

Nondestructive Evaluation Of Thermal Barrier Coatings With Thermal Wave Imaging And Photostimulated Luminescence Spectroscopy, Barbara Franke

Electronic Theses and Dissertations

Gas Turbine manufacturers strive for increased operating temperatures of gas turbine engines to improve efficiency and performance. One method of increasing the temperature beyond material limits is by applying thermal barrier coatings (TBCs) to hot section components. TBCs provide a thermal gradient between the hot gases and metallic substrate, and allow an increase in turbine inlet temperatures of 100-150ºC. However, spallation of TBCs can cause catastrophic failure of turbine engines by incipient melting of the substrate. To prevent such an occurrence, non-destructive evaluation (NDE) techniques are critical for quality control, health monitoring, and life assessment of TBCs. Two techniques in …

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High Voltage Bias Testing And Degradation Analysis Of Photovoltaic Modules, Vinaykumar Hadagali Jan 2005

High Voltage Bias Testing And Degradation Analysis Of Photovoltaic Modules, Vinaykumar Hadagali

Electronic Theses and Dissertations

This thesis mainly focuses on two important aspects of the photovoltaic modules. The first aspect addressed the high voltage bias testing and data and degradation analysis of high voltage biased thin film photovoltaic modules. The second aspect addressed the issues of reliability and durability of crystalline silicon module. Grid-connected photovoltaic systems must withstand high voltage bias in addition to harsh environmental conditions such as intermittent solar irradiance, high humidity, heat and wind. a-Si:H thin-film photovoltaic modules with earlier generation SnO2:F transparent conducting oxide (TCO) on the front glass installed on the FSEC High Voltage Test Bed were monitored since December …

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Arc-Discharge In Solution: A Novel Synthesis Method For Carbon Nanotubes And In Situ Decoration Of Carbon Nanotubes With Nanoparticles, Debasis Bera Jan 2005

Arc-Discharge In Solution: A Novel Synthesis Method For Carbon Nanotubes And In Situ Decoration Of Carbon Nanotubes With Nanoparticles, Debasis Bera

Electronic Theses and Dissertations

Nanotechnology has reached the status of the 21st century's leading science and technology based on fundamental and applied research during the last two decades. An important feature of nanotechnology is to bridge the crucial dimensional gap between the atomic and molecular fundamental sciences and microstructural scale of engineering. Accordingly, it is very important to have an in-depth understanding of the synthesis of nanomaterials for the use of state-of-the-art high technological devices with enhanced properties. Recently, the 'bottom-up' approach for the fabrication of nanomaterials has received a great deal of attention for its simplicity and cost effectiveness. Tailoring the various parameters …

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Transmission Electron Microscopy Studies In Shape Memory Alloys, Madhavi Tiyyagura Jan 2005

Transmission Electron Microscopy Studies In Shape Memory Alloys, Madhavi Tiyyagura

Electronic Theses and Dissertations

In NiTi, a reversible thermoelastic martensitic transformation can be induced by temperature or stress between a cubic (B2) austenite phase and a monoclinic (B19') martensite phase. Ni-rich binary compositions are cubic at room temperature (requiring stress or cooling to transform to the monoclinic phase), while Ti-rich binary compositions are monoclinic at room temperature (requiring heating to transform to the cubic phase). The stress induced transformation results in the superelastic effect, while the thermally induced transformation is associated with strain recovery that results in the shape memory effect. Ternary elemental additions such as Fe can additionally introduce an intermediate rhombohedral (R) …

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Development Of Transparent And Conducting Back Contacts On Cds/Cdte Solar Cells For Photoelectrochemical Application, Upendra Sureshchandra Avachat Jan 2005

Development Of Transparent And Conducting Back Contacts On Cds/Cdte Solar Cells For Photoelectrochemical Application, Upendra Sureshchandra Avachat

Electronic Theses and Dissertations

The development of devices with high efficiencies can only be attained by tandem structures which are important to the advancement of thin-film photoelectrochemical (PEC) and photovoltaic (PV) technologies. FSEC PV Materials Lab has developed a PEC cell using multiple bandgap tandem of thin film PV cells and a photocatalyst for hydrogen production by water splitting. CdS/CdTe solar cell, a promising candidate for low-cost, thin-film PV cell is used as one of the thin film solar cells in a PEC cell. This research work focuses on developing various back contacts with good transparency in the infrared region (~750 - 1150 nm) …

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Interdiffusion Analysis For Nicocraly And Nial Vs. Various Superalloys, Emmanuel Perez Jan 2005

Interdiffusion Analysis For Nicocraly And Nial Vs. Various Superalloys, Emmanuel Perez

Electronic Theses and Dissertations

Hot section components in gas turbines can be NiCoCrAlY-coated to provide the component with an Al reservoir that maintains a protective oxide layer on its surface. Over the service life of the component, the coatings degrade by composition and phase changes due to oxidation/hot-corrosion, and multicomponent interdiffusion from and into the superalloy substrate. In this study, the rate of Al interdiffusion into selected Ni-base superalloys using various diffusion couples of two-phase NiCoCrAlY (beta + gamma) and single beta-phase NiAl with the selected alloys is measured. The diffusion couples were examined with an emphasis on the composition-dependence of Al interdiffusion. Microstructural …

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