Open Access. Powered by Scholars. Published by Universities.®
Materials Science and Engineering Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Biology and Biomimetic Materials (15)
- Mechanical Engineering (12)
- Electrical and Computer Engineering (8)
- Ceramic Materials (7)
- Semiconductor and Optical Materials (7)
-
- Polymer and Organic Materials (6)
- Aerospace Engineering (5)
- Applied Mechanics (4)
- Biomedical Engineering and Bioengineering (4)
- Manufacturing (4)
- Metallurgy (4)
- Civil and Environmental Engineering (3)
- Engineering Science and Materials (3)
- Medicine and Health Sciences (3)
- Nanomedicine (3)
- Nanotechnology (3)
- Other Materials Science and Engineering (3)
- Structural Materials (3)
- Biomaterials (2)
- Computer Engineering (2)
- Electrical and Electronics (2)
- Electro-Mechanical Systems (2)
- Energy Systems (2)
- Environmental Engineering (2)
- Mechanics of Materials (2)
- Medical Specialties (2)
- Physical Sciences and Mathematics (2)
- Power and Energy (2)
- Keyword
-
- Diffusion (6)
- Nanocomposites (6)
- Interdiffusion (5)
- Polymer derived ceramics (5)
- TEM (5)
-
- Aluminum (4)
- Molybdenum (4)
- Nanocomposite (4)
- Shape memory alloys (4)
- 3D Printing (3)
- CIGS (3)
- Carbon nanotubes (3)
- Ceramics (3)
- Ceria (3)
- Magnesium (3)
- Microstructure (3)
- Nanomaterials (3)
- Nanotechnology (3)
- NiTi (3)
- Photovoltaics (3)
- Sol-gel (3)
- Solar cells (3)
- Thin film (3)
- Actuator (2)
- Agglomeration (2)
- Alumina (2)
- Basalt fiber (2)
- Bile acids (2)
- Biosensor (2)
- CIGS2 (2)
- Publication Year
- Publication
- Publication Type
Articles 121 - 150 of 214
Full-Text Articles in Materials Science and Engineering
Direct Measurement Of Thicknesses, Volumes Or Compositions Of Nanomaterials By Quantitative Atomic Number Contrast In High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy, Biao Yuan
Electronic Theses and Dissertations
The sizes, shapes, volumes and compositions of nanoparticles are very important parameters determining many of their properties. Efforts to measure these parameters for individual nanoparticles and to obtain reliable statistics for a large number of nanoparticles require a fast and reliable method for 3-D characterization. In this dissertation, a direct measurement method for thicknesses, volumes or compositions of nanomaterials by quantitative atomic number contrast in High-Angle Annular Dark-Field (HAADF) Scanning Transmission Electron Microscopy (STEM) is presented. A HAADF detector collects electrons scattered incoherently to high angles. The HAADF signal intensity is in first-order approximation proportional to the sample thickness and …
Microstructual Characteristics Of Magnesium Metal Matrix Composites, Dongho Shin
Microstructual Characteristics Of Magnesium Metal Matrix Composites, Dongho Shin
Electronic Theses and Dissertations
Magnesium (Mg) Metal matrix composites (MMCs) reinforced by ceramic reinforcements are being developed for a variety of applications in automotive and aerospace because of their strength-to-weight ratio. Reinforcement being considered includes SiC, Al2O3, Carbon fiber and B4C in order to improve the mechanical properties of MMCs. Microstructural and interfacial characteristics of MMCs can play a critical role in controlling the MMCs’ mechanical properties. This study was carried out to understand the microstructural and interfacial development between Mg-9wt.Al-1wt.Zn (AZ91) alloy matrix and several reinforcements including SiC, Al2O3, Carbon fibers and B4C. X-ray diffraction, scanning electron microscopy and transmission electron microscopy was …
Phase Field Modeling Of Thermotransport In Multicomponent Systems, Joshua Bush
Phase Field Modeling Of Thermotransport In Multicomponent Systems, Joshua Bush
Electronic Theses and Dissertations
Nuclear and gas turbine power plants, computer chips, and other devices and industries are running hotter than ever for longer than ever. With no apparent end to the trend, the potential arises for a phenomenon known as thermotransport to cause undesirable changes in these high temperature materials. The diffuse-interface method known as the phase-field model is a useful tool in the simulation and prediction of thermotransport driven microstructure evolution in materials. The objective of this work is to develop a phase-field model using practical and empirical properties of thermodynamics and kinetics for simulating the interdiffusion behavior and microstructural evolution of …
Diffusion And Reaction In Selected Uranium Alloy System, Ke Huang
Diffusion And Reaction In Selected Uranium Alloy System, Ke Huang
Electronic Theses and Dissertations
U-Mo metallic fuels with Al alloys as the matrix/cladding are being developed as low enriched uranium fuels under the Reduced Enrichment for Research and Test Reactor (RERTR) program. Significant interactions have been observed to occur between the U-Mo fuel and the Al alloy during fuel processing and irradiation. U-Zr metallic fuels with stainless steel claddings have been developed for the generation IV sodium fast reactor (SFR). The fuel cladding chemical interaction (FCCI) induced by the interdiffusion of components was also observed. These interactions induce deleterious effects on the fuel system, such as thinning of the cladding layer, formation of phases …
Synthesis And Properties Of Self-Assembled C/Sicn Nanocomposite Derived From Polymer Precursors, Cheng Li
Synthesis And Properties Of Self-Assembled C/Sicn Nanocomposite Derived From Polymer Precursors, Cheng Li
Electronic Theses and Dissertations
The properties of C/SiCN nanocomposites synthesized by thermal decomposition of polymer precursors were studied in this work. The novel polymer-to-ceramic process enables us to tailor the ceramic structure in atomic level by designing the starting chemicals and pyrolysis procedures. It is of both fundamental and practical significance to investigate the properties and structures relationship of the nanocomposites. In this work, we explored their application potential in using as anode of lithium-ion secondary batteries. The structure and structural evolution of C/SiCN nanocomposite were investigated by using XRD, FTIR, SEM, TEM, Solid state NMR and Raman spectroscopy. The results revealed the nanocomposites …
Rare Earth Oxide Coating With Controlled Chemistry Using Thermal Spray, Virendra Singh
Rare Earth Oxide Coating With Controlled Chemistry Using Thermal Spray, Virendra Singh
Electronic Theses and Dissertations
Cerium oxide (Ceria) at nano scale has gained significant attention due to its numerous technological applications. Ceria in both doped and undoped forms are being explored as oxygen sensor, catalysis, protective coating against UV and corrosion, solid oxide fuel cell (SOFC) electrolyte and newly discovered antioxidant for biomedical applications. Therefore, there is an imminent need of a technology which can provide a cost effective, large scale manufacturing of nanoceria and its subsequent consolidation, specially using thermal spray. This dissertation aims to develop a scientific understanding towards the development of pure and doped ceria- based coating for a variety of technological …
Processing, Characterization And Performance Of Carbon Nanopaper Based Multifunctional Nanocomposites, Fei Liang
Electronic Theses and Dissertations
Carbon nanofibers (CNFs) used as nano-scale reinforcement have been extensively studied since they are capable of improving the physical and mechanical properties of conventional fiber reinforced polymer composites. However, the properties of CNFs are far away from being fully utilized in the composites due to processing challenges including the dispersion of CNFs and the viscosity increase of polymer matrix. To overcome these issues, a unique approach was developed by making carbon nanopaper sheet through the filtration of well-dispersed carbon nanofibers under controlled processing conditions, and integrating carbon nanopaper sheets into composite laminates using autoclave process and resin transfer molding (RTM). …
Understanding The Role Of Defects In The Radiation Response Of Nanoceria, Amit Kumar
Understanding The Role Of Defects In The Radiation Response Of Nanoceria, Amit Kumar
Electronic Theses and Dissertations
Nanoscale cerium oxide (nanoceria) have shown to possess redox active property , and has been widely studied for potential use in catalysis, chemical-mechanical planarization, biomedical and solid oxide fuel cell (SOFC), etc. The redox state of nanoceria can be tuned by controlling the defects within the lattice and thus its physical and chemical properties. Perfect ceria lattice has fluorite structure and the research in last decade has shown that oxide and mixed oxide systems with pyrochlore and fluorite have better structural stability under high energy radiation. However, the current literature shows a limited number of studies on the effect of …
Structure And Properties Of Polymer-Derived Sibcn Ceramics, Yaohan Chen
Structure And Properties Of Polymer-Derived Sibcn Ceramics, Yaohan Chen
Electronic Theses and Dissertations
Polymer-derived ceramics (PDCs) are a unique class of multifunctional materials synthesized by thermal decomposition of polymeric precursors. Due to their unique and excellent properties and flexible manufacturing capability, PDC is a promising technology to prepare ceramic fibers, coatings, composites and micro-sensors for high-temperature applications. However, the structure-property relationships of PDCs have not been well understood. The lack of such understandings drastically limited the further developments and applications of the materials. In this dissertation, the structure and properties of amorphous polymer-derived silicon carbonitride (SiCN) and silicoboron carbonitride (SiBCN) have been studied. The SiCN was obtained using commercially available polysilazane as pre-ceramic …
Developing Surface Engineered Liquid Crystal Droplets For Sensing Applications, Tanmay Bera
Developing Surface Engineered Liquid Crystal Droplets For Sensing Applications, Tanmay Bera
Electronic Theses and Dissertations
Diagnosis plays a very crucial role in medicine and health care, which makes biosensors extremely important in modern technological context. Till date, various types of biosensors have been developed that are capable of detecting a wide range of biologically important species with great sensitivity and selectivity. However, most of these sensing units require highly sophisticated instrumentation and often lack the desired portability. Liquid crystal (LC) droplets, on the other hand, are a new type of functional material that are finding increasing research attention as a new sensing unit due to their tunable optical property, high surface area, portability and cost-effectiveness. …
Optimization Of Process Parameters For Faster Deposition Of Cuin1-Xgaxs2 And Cuin1-Xgaxse2-Ysy Thin Film Solar Cells, Ashwani Kaul
Optimization Of Process Parameters For Faster Deposition Of Cuin1-Xgaxs2 And Cuin1-Xgaxse2-Ysy Thin Film Solar Cells, Ashwani Kaul
Electronic Theses and Dissertations
Thin film solar cells have the potential to be an important contributor to the world energy demand in the 21st century. Among all the thin film technologies, CuInGaSe2 (CIGS) thin film solar cells have achieved the highest efficiency. However, the high price of photovoltaic (PV) modules has been a major factor impeding their growth for terrestrial applications. Reduction in cost of PV modules can be realized by several ways including choosing scalable processes amenable to large area deposition, reduction in the materials consumption of active layers, and attaining faster deposition rates suitable for in-line processing. Selenization-sulfurization of sputtered metallic Cu-In-Ga …
Effects Of Allotropic Transformations On Interdiffusion Behavior In Binary Systems, Ashley Elizabeth Ewh
Effects Of Allotropic Transformations On Interdiffusion Behavior In Binary Systems, Ashley Elizabeth Ewh
Electronic Theses and Dissertations
Diffusion plays a significant role in most materials systems by controlling microstructural development. Consequently, the overall properties of a material can be largely dependent upon diffusion. This study investigated the interdiffusion behavior of three binary systems, namely, Mo-Zr, Fe-Mo, and Fe-Zr. The main interest in these particular metals is for application in nuclear fuel assemblies. Nuclear fuel plates generally consist of two main components which are the fuel and the cladding. Due to diffusional interactions that can occur between these two components, a third is sometimes added between the fuel and cladding to serve as a diffusion barrier layer. Fe, …
Thermally Annealled Plasmonic Nanostructures, Chaoming Wang
Thermally Annealled Plasmonic Nanostructures, Chaoming Wang
Electronic Theses and Dissertations
Localized surface plasmon resonance (LSPR) is induced in metal nanoparticles by resonance between incident photons and conduction electrons in nanoparticles. For noble metal nanoparticles, LSPR can lead to strong absorbance of ultraviolet-violet light. Although it is well known that LSPR depends on the size and shape of nanoparticles, the inter-particle spacing, the dielectric properties of metal and the surrounding medium, the temperature dependence of LSPR is not well understood. By thermally annealing gold nanoparticle arrays formed by nanosphere lithography, a shift of LSPR peak upon heating has been shown. The thermal characteristics of the plasmonic nanoparticles have been further used …
Multiscale Simulation Of Laser Ablation And Processing Of Semiconductor Materials, Lalit Shokeen
Multiscale Simulation Of Laser Ablation And Processing Of Semiconductor Materials, Lalit Shokeen
Electronic Theses and Dissertations
We present a model of laser-solid interactions in silicon based on an empirical potential developed under conditions of strong electronic excitations. The parameters of the interatomic potential depends on the temperature of the electronic subsystem Te, which is directly related to the density of the electron-hole pairs and hence the number of broken bonds. We analyze the dynamics of this potential as a function of electronic temperature Te and lattice temperature Tion. The potential predicts phonon spectra in good agreement with finite-temperature densityfunctional theory, including the lattice instability induced by the high electronic excitations. For 25fs pulse, a wide range …
Process-Dependent Microstructure And Severe Plastic Deformation In Sicp?? Reinforced Aluminum Metal Matrix Composites, Catalina Uribe-Restrepo
Process-Dependent Microstructure And Severe Plastic Deformation In Sicp?? Reinforced Aluminum Metal Matrix Composites, Catalina Uribe-Restrepo
Electronic Theses and Dissertations
Discontinuously reinforced MMCs with optimized microstructure are sought after for exceptional high strain rate behavior. The microstructure evolution of a stir-cast A359 aluminum composite reinforced with 30 vol.% SiCp after isothermal anneal, successive hot-rolling, and high strain rate deformation has been investigated. Quantitative microstructural analysis was carried out for the as-cast, annealed (470°C, 538°C and 570°C) and successively hot rolled specimens (64, 75, 88, and 96% rolling reductions). Selected composites were also examined after high strain rate deformation. X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy were employed for microstructural characterization. The strength and ductility of the …
Fatigue Lifetime Approximation Based On Quantitative Microstructural Analysis For Air Plasma Sprayed Thermal Barrier Coatings, Carmen Bargraser
Fatigue Lifetime Approximation Based On Quantitative Microstructural Analysis For Air Plasma Sprayed Thermal Barrier Coatings, Carmen Bargraser
Electronic Theses and Dissertations
The durability of thermal barrier coatings (TBCs) affects the life of the hot section engine components on which they are applied. Fatigue is the general failure mechanism for such components and is responsible for most unexpected failures; therefore it is desirable to develop lifetime approximation models to ensure reliability and durability. In this study, we first examined the microstructural degradation of air plasma sprayed ZrO2-8wt.%Y2O3 TBCs with a low-pressure plasma sprayed CoNiCrAlY bond coat on an IN 738LC superalloy substrate. The durability of TBCs were assessed through furnace thermal cyclic tests carried out in air at 1100°C with a 1-, …
Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi
Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi
Electronic Theses and Dissertations
Molybdenum (Mo) thin film back contact layers for thin film CuIn(1-x)GaxSe2 (CIGS) solar cells were deposited onto soda lime glass substrates using a direct current (DC) planar magnetron sputtering deposition technique. Requirements for the Mo thin film as a back contact layer for CIGS solar cells are various. Sheet resistance, contact resistance to the CIGS absorber, optical reflectance, surface morphology, and adhesion to the glass substrate are the most important properties that the Mo thin film back contact layer must satisfy. Experiments were carried out under various combinations of sputtering power and working gas pressure, for it is well known …
Tunable Infrared Metamaterials, David Shelton
Tunable Infrared Metamaterials, David Shelton
Electronic Theses and Dissertations
Metamaterials are engineered periodic composites that have unique refractive-index characteristics not available in natural materials. They have been demonstrated over a large portion of the electromagnetic spectrum, from visible to radiofrequency. For applications in the infrared, the structure of metamaterials is generally defined using electron-beam lithography. At these frequencies, the loss and dispersion of any metal included in the composite are of particular significance. In this regard, we investigate deviations from the Drude model due to the anomalous skin effect. For comparison with theoretical predictions, the optical properties of several different metals are measured, both at room temperature and at …
Probing The Nanoscale Interaction Forces And Elastic Properties Of Organic And Inorganic Materials Using Force-Distance (F-D) Spectroscopy, Abhilash Vincent
Probing The Nanoscale Interaction Forces And Elastic Properties Of Organic And Inorganic Materials Using Force-Distance (F-D) Spectroscopy, Abhilash Vincent
Electronic Theses and Dissertations
Due to their therapeutic applications such as radical scavenging, MRI contrast imaging, Photoluminescence imaging, drug delivery, etc., nanoparticles (NPs) have a significant importance in bio-nanotechnology. The reason that prevents the utilizing NPs for drug delivery in medical field is mostly due to their biocompatibility issues (incompatibility can lead to toxicity and cell death). Changes in the surface conditions of NPs often lead to NP cytotoxicity. Investigating the role of NP surface properties (surface charges and surface chemistry) on their interactions with biomolecules (Cells, protein and DNA) could enhance the current understanding of NP cytotoxicity. Hence, it is highly beneficial to …
Environmental Degradation Of Oxidation Resistant And Thermal Barrier Coatings For Fuel-Flexible Gas Turbine Applications, Prabhakar Mohan
Environmental Degradation Of Oxidation Resistant And Thermal Barrier Coatings For Fuel-Flexible Gas Turbine Applications, Prabhakar Mohan
Electronic Theses and Dissertations
The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air …
Branched And Spiral Organic Nanotubes Based On The Self-Assembly Of Bile Acids, Xuejun Zhang
Branched And Spiral Organic Nanotubes Based On The Self-Assembly Of Bile Acids, Xuejun Zhang
Electronic Theses and Dissertations
The self-assembly of chiral amphiphilic molecules in aqueous solutions is of particular interest because the chirality of individual molecules is often expressed in their supermolecular structures. Self-assembled tubes made of chiral amphiphilic molecules represent useful supramolecular architectures which hold promise as controlled release vehicles for drug delivery, encapsulates for functional molecules, and nanoreactors for chemical reactions. Lithocholic acid (LCA) is a secondary bile acid with the concentration being identical to that of cholesterol in the hepatic bile and gallbladder. It has a rigid, nearly planar hydrophobic steroid nucleus, with four hydrogen atoms and one hydroxyl group directed toward the concave …
Structural Characterization Of Sputter-Deposited Ss304+Xal (X = 0, 4, 7 And 10 Wt.%) Coatings And Mechanically Milled Ti, Zr And, Uma Maheswara Seelam
Structural Characterization Of Sputter-Deposited Ss304+Xal (X = 0, 4, 7 And 10 Wt.%) Coatings And Mechanically Milled Ti, Zr And, Uma Maheswara Seelam
Electronic Theses and Dissertations
Study of the metastable phases obtained by non-equilibrium processing techniques has come a long way during the past five decades. New metastable phases have often given new perspectives to the research on synthesis of novel materials systems. Metastable materials produced by two non-equilibrium processing methods were studied for this dissertation- 304-type austenitic stainless steel (SS304 or Fe-18Cr-8Ni)+aluminum coatings produced by plasma enhanced magnetron sputter-deposition (PEMS) and nanocrystalline Ti, Zr and Hf powders processed by mechanical milling (MM). The objective of the study was to understand the crystallographic and microstructural aspects of these materials. Four SS304+Al coatings with a nominal Al …
Microstructural Investigation Of Precipitation Hardened Cuni2s+Zr Alloys For Rotor Applications, Jean-Paul Vega-Garcia
Microstructural Investigation Of Precipitation Hardened Cuni2s+Zr Alloys For Rotor Applications, Jean-Paul Vega-Garcia
Electronic Theses and Dissertations
Industrial generator components experience high stresses and electrical fields during their service life. Material integrity is key in guaranteeing component performance. CuNi2SiZr, used as rotor wedges in generators, serve to maintain rotor slot content in place while experiencing high centrifugal stresses and low cycle fatigue during start and stop at elevated temperature. The quality and integrity of this material in service can be directly related to its microstructure, which is determined by the processing procedures of the wedges. In this study, the microstructure development in this material is evaluated to eliminate grain boundary defects by optimizing processing parameters, determining the …
Investigation Of Thermal, Elastic And Load-Biased Transformation Strains In Niti Shape Memory Alloys, Shipeng Qiu
Investigation Of Thermal, Elastic And Load-Biased Transformation Strains In Niti Shape Memory Alloys, Shipeng Qiu
Electronic Theses and Dissertations
Polycrystalline NiTi shape memory alloys have the ability to recover their original, pre-deformed shape in the presence of external loads when heated through a solid-solid phase transformation from a lower-symmetry B19' martensite phase to a higher-symmetry B2 austenite phase. The strain associated with a shape memory alloy in an actuator application typically has thermal, elastic and inelastic contributions. The objective of this work was to investigate the aforementioned strains by recourse to in situ neutron diffraction experiments during selected combinations of heating, cooling and/or mechanical loading. The primary studies were conducted on polycrystalline Ni49.9Ti50.1 specimens on the Spectrometer for MAterials …
Strengthening Potential Of Single-Walled Carbon Nanotubes In Phenolic Resin Composites, Brittany Kerr
Strengthening Potential Of Single-Walled Carbon Nanotubes In Phenolic Resin Composites, Brittany Kerr
Electronic Theses and Dissertations
Strengthening potential of single-walled carbon nanotubes (SWCNTs) in a phenolic resin composite was evaluated by characterization of purified and phenyl sulfonated SWCNTs, investigation of the load transfer capability of the purified SWCNTs, and characterization of the composites. Purified and phenyl sulfonated SWCNTs, as well as their composites, were examined by Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and ultra violet-visible spectrometry. Fabrication of the SWCNT/phenolic resin composite was performed by first dispersing the SWCNTs in ethylene glycol and then homogenizing the mixture with phenolic resin. The ethylene glycol was …
Thermal Detection Of Biomarkers Using Phase Change Nanoparticles, Chaoming Wang
Thermal Detection Of Biomarkers Using Phase Change Nanoparticles, Chaoming Wang
Electronic Theses and Dissertations
Most of existing techniques cannot be used to detect molecular biomarkers (i.e., protein and DNA) contained in complex body fluids due to issues such as enzyme inhibition or signal interference. This thesis describes a nanoparticle-based thermal detection method for the highly sensitive detections of multiple DNA biomarkers or proteins contained in different type of fluids such as buffer solution, cell lysate and milk by using solid-liquid phase change nanoparticles as thermal barcodes. Besides, this method has also been applied for thrombin detection by using RNA aptamer-functionalized phase change nanoparticles as thermal probes. Furthermore, using nanostructured Si surface that have higher …
Phase-Field Simulation Of Microstructural Development Induced By Interdiffusion Fluxes Under Multiple Gradients, Rashmi Mohanty
Phase-Field Simulation Of Microstructural Development Induced By Interdiffusion Fluxes Under Multiple Gradients, Rashmi Mohanty
Electronic Theses and Dissertations
The diffuse-interface phase-field model is a powerful method to simulate and predict mesoscale microstructure evolution in materials using fundamental properties of thermodynamics and kinetics. The objective of this dissertation is to develop phase-field model for simulation and prediction of interdiffusion behavior and evolution of microstructure in multiphase binary and ternary systems under composition and/or temperature gradients. Simulations were carried out with emphasis on multicomponent diffusional interactions in single-phase system, and microstructure evolution in multiphase systems using thermodynamics and kinetics of real systems such as Ni-Al and Ni-Cr-Al. In addition, selected experimental studies were carried out to examine interdiffusion and microstructure …
Multicomponent Interdiffusion In Austenitic Ni-, Fe-Ni-Base Alloys And L12-Ni3al Intermetallic For High-Temperature Applications, Narayana Garimella
Multicomponent Interdiffusion In Austenitic Ni-, Fe-Ni-Base Alloys And L12-Ni3al Intermetallic For High-Temperature Applications, Narayana Garimella
Electronic Theses and Dissertations
Interdiffusion in multicomponent-multiphase alloys is commonly encountered in many materials systems. The developments of multicomponent-multiphase alloys require control of microstructure through appropriate heat treatment, involving solid-state transformations, precipitation processes, and surface modification, where the interdiffusion processes play a major role. In addition, interdiffusion processes often control degradation and failure of these materials systems. Enhanced performance and reliable durability always requires a detailed understanding of interdiffusion. In this study, ternary and quaternary interdiffusion in Ni-Cr-X (X = Al, Si, Ge, Pd) at 900°C and 700°C, Fe-Ni-Cr-X (X = Si, Ge) at 900°C, and Ni3Al alloyed with Ir, Ta and Re at …
Formation Of Lyotropic Liquid Crystals Through The Self-Assembly Of Bile Acid Building Blocks, Karan Tamhane
Formation Of Lyotropic Liquid Crystals Through The Self-Assembly Of Bile Acid Building Blocks, Karan Tamhane
Electronic Theses and Dissertations
Liquid crystalline materials (LCMs) have gained much popularity over the past century. The thermotropic forms of these materials have been extensively studied and employed in a range of innovative applications. The lyotropic liquid crystal systems that have been studied in the past have often been formed by the organization of natural and synthetic small molecules in solutions. In this study, we use self-assembled supramolecular structures as building blocks to fabricate lyotropic liquid crystals. We investigate the self-assembly of a naturally occurring bile acid called lithocholic acid (LCA), to form supramolecular fibrous and tubular structures in basic aqueous solutions. We control …
Electronic Properties And Microstructures Of Amorphous Sicn Ceramics Derived From Polymer Precursors, Tao Jiang
Electronic Properties And Microstructures Of Amorphous Sicn Ceramics Derived From Polymer Precursors, Tao Jiang
Electronic Theses and Dissertations
Polymer-derived ceramics (PDCs) are a new class of high-temperature materials synthesized by thermal decomposition of polymeric precursors. These materials possess many unique features as compared with conventional ceramics synthesized by powder metallurgy based processing. For example, PDCs are neither amorphous nor crystalline. Instead, they possess nano-domain structures. Due to the direct chemical-to-ceramic processing, PDCs can be used for making components and devices with complex shapes. Thus, understanding the properties and structures of these materials are of both fundamental and practical interest. In this work, the structures and electronic behavior of polymer-derived amorphous silicon carbonitrides (SiCNs) were investigated. The materials were …