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Articles 271 - 300 of 310
Full-Text Articles in Materials Science and Engineering
Mse News 2009, Department Of Materials Science And Engineering, Michigan Technological University
Mse News 2009, Department Of Materials Science And Engineering, Michigan Technological University
Department of Materials Science and Engineering Annual Reports
Table of Contents
- MSE Department Welcomes Engineering Fundamentals Chair
- MSE Department Welcomes New Professor
- Steel
- MSE Program Shines in US News Rankings
- MSE Alumnus Excelled in Mining Industry
- Student News
- Staff News
- Faculty News
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Model For Alumina Nanopore-Based Optical Filter, Nathan Lehman, Rama Venkat, Robert A. Schill
Model For Alumina Nanopore-Based Optical Filter, Nathan Lehman, Rama Venkat, Robert A. Schill
Electrical & Computer Engineering Faculty Research
Alumina nanopore structures find applications in magnetic sensors, optical filters, and various biological devices. In this work, we present a ray-optics model for the optical filter. We present a detailed simulation and a simplified analytical expression for the reflectance as a function of the alumina parameters such as pore diameter, pore density, alumina thickness, and a function of the wavelength and angle of incidence of the illuminating plane electromagnetic wave. The reflectance vs wavelength in the range of 400–800nm obtained from the simulation and the analytical expression are compared with that of the experiments for thin and thick alumina. All …
The Effect Of Near-Surface Metallurgy On The Machinability Of Cast Iron, William Dewey Peach
The Effect Of Near-Surface Metallurgy On The Machinability Of Cast Iron, William Dewey Peach
Masters Theses
"The increasing performance and durability of cutting tool inserts have created metallurgical challenges for production foundries to produce near-net shaped castings within strict dimensional tolerances. In order for foundries to take full advantage of the increased cutting speed capabilities, it becomes necessary to reduce machining allowances and produce much more stable casting surfaces. To accomplish this, a better understanding of the complex microstructures formed within the first 0.120 in. (3 mm) of the mold/metal interface (as-cast surface) is necessary. The goal of the work presented here was to examine the microstructures formed in the near-surface region of gray iron castings, …
Friction Stir Processing Of Laser Metal Deposited Ti-6al-4v, Romy Francis
Friction Stir Processing Of Laser Metal Deposited Ti-6al-4v, Romy Francis
Masters Theses
"Laser metal deposition (LMD) can form near net shaped components for aerospace applications. Ti-6Al-4V is a widely used aerospace alloy and fabrication of this alloy using LMD is gaining popularity. Improved mechanical properties are always a requirement in aerospace alloys and research is constantly being conducted to improve the properties of components formed from this alloy. Friction Stir Processing (FSP) in the past has been used as a method to change the surface properties of materials through microstructural modifications. The changes in properties can include hardness, corrosion resistance, fatigue strength, etc. The first section of this thesis is based on …
Friction Stir Processing Of Magnesium Alloys, Gaurav Bhargava
Friction Stir Processing Of Magnesium Alloys, Gaurav Bhargava
Masters Theses
"Magnesium alloys have been fast catching up their attention in applications where both lightweight and exceptional strength is desired. But magnesium alloys suffer formability issues which limit their use to cast applications when designing complicated shapes. Friction stir processing (FSP) is technique for, imparting a fine-grained, homogeneous microstructure by which both strength and ductility can be enhanced. The results from the first part of present work showed that AZ31 alloy when employed the use of FSP, yielded significant strength and ductility gains but on the cost of anisotropy. The cause of anisotropy was investigated to be correlated to texture evolution …
The Corrosion Of Ni₃Si Alloys In Sulfuric Acid, Christopher Marc Larson
The Corrosion Of Ni₃Si Alloys In Sulfuric Acid, Christopher Marc Larson
Masters Theses
"Hydrogen production from water, the world's most renewable natural resource, can provide an economical and sustainable form of energy for the future. One means to achieve this is with a nuclear reactor-based sulfur-iodine (S-I) thermochemical cycle. Currently there are few materials available, other than precious metals like gold and platinum, that possess the corrosion resistance and mechanical properties required for the sulfuric acid decomposition loop of the S-I process. However, alloys based on Ni₃Si show promise to be a more affordable, corrosion resistant materials option for this technology. In this study, the corrosion behavior of NiSi₂₂ and NiSi₂₀(Nb,Ti)₃ alloys in …
Investment Shell Cracking, Edward A. Druschitz
Investment Shell Cracking, Edward A. Druschitz
Masters Theses
"Shell cracking is the single greatest problem affecting investment casters. A clearer understanding of the factors affecting the melt profile of the wax can be gained using computational fluid dynamics (CFD) to model the interaction among 1) the thermal conductivity of the wax, 2) the thermal conductivity of the shell, and 3) the temperature of the autoclave during the autoclave de-waxing cycle. The most favorable melt profile results from a high autoclave temperature (438⁰K to 458⁰K) and saturated thermal conductivity of the shell (1.36 to 1.40 Wm⁻¹k⁻¹) in conjunction with a low wax thermal conductivity (0.33 Wm⁻¹k⁻¹). These parameters reduce …
Quench Factor Analysis Of Wrought And Cast Aluminum Alloys, Vishwanath Gandikota
Quench Factor Analysis Of Wrought And Cast Aluminum Alloys, Vishwanath Gandikota
Masters Theses
"Mechanical property variation across the cross section of heat treatable aluminum alloys is a major concern. To minimize such variation, a proper understanding of kinetic transformations and estimation of mechanical properties is required. The Jominy end quench test has been used successfully to study the effect of quench rate on the final heat treated properties of wrought and cast aluminum alloys. This test produces varying cooling rates along the length of a cylindrical sample cooled with water at one end. Jominy bars of wrought and cast aluminum alloys were solutionized, endquenched, and aged to T6 temper condition after delays of …
Spectroscopic Characterizations Of Organic/Inorganic Nanocomposites, Jayesh Rasikalal Govani
Spectroscopic Characterizations Of Organic/Inorganic Nanocomposites, Jayesh Rasikalal Govani
Open Access Theses & Dissertations
Inorganic potassium dihydrogen phosphate (KDP) is widely known for its value as a nonlinear optical material. In this study, pure and l-arginine-doped KDP single crystals were grown by the slow solvent evaporation technique and further subjected to infrared absorption and Raman studies for the confirmation of chemical group functionalization and possible bonding between the organic and inorganic materials. The appearance in the infrared absorption spectra of additional vibrational lines, which mostly originate from disturbed N-H, C-H, and C-N bonds of the l-arginine-doped salt, confirm the interaction between KDP and the organic material. This affirmation is supported by more evidence from …
Computational Modeling Studies Of The Structures And Properties Of Organotin(Iv) And Stannyl-Thioether Systems With Comparisons To X-Ray Crystallography, Michelle R. Stem Joseph
Computational Modeling Studies Of The Structures And Properties Of Organotin(Iv) And Stannyl-Thioether Systems With Comparisons To X-Ray Crystallography, Michelle R. Stem Joseph
Open Access Theses & Dissertations
Controlling the toxic effects of organotin(IV) compounds involves engineering the structure of the molecules to optimize their properties. Molecular engineering, coupled with improved capabilities to generate reliable computational optimization models (COMs), will enable researchers to have greater success at harnessing the highly specific cytotoxicity of organotins. For example, as the thion ligand phenyl groups were replaced with Cl atoms, the S-Sn intramolecularity was strengthened, the bond distance decreased, and the stannyl tetrahedral structure was deformed from its triphenyl conformation. With each substitution, conformation deformations lowered the damaging bioactivity levels of thion. Bonding various ligands to organotin(IV) compounds …
High Temperature Oxidation Behavior Of Nb-20mo-15si-5b-20cr Alloy, Julieta Angelica Ventura
High Temperature Oxidation Behavior Of Nb-20mo-15si-5b-20cr Alloy, Julieta Angelica Ventura
Open Access Theses & Dissertations
Materials for high temperature applications, such as jet engines, gas turbines and turbine blades, require a balanced combination of physical and chemical properties to withstand the aggressive environments in which they are utilized. Some of the properties required are high strength, low density, high melting point and good oxidation resistance at elevated temperatures [1-3]. For this reason, the microstructure and oxidation behavior of the Nb-20Mo-15Si-5B-20Cr alloy (at.%) has been studied as a potential candidate to replace Nickel-based alloys currently used in the aerospace industry.
Short term oxidation (STO) and long term oxidation (LTO) studies have been performed in air for …
Observed Superspin-Glass Behavior In Ni0.5zn0.5fe2o4 Nanoparticles, Antony Adair
Observed Superspin-Glass Behavior In Ni0.5zn0.5fe2o4 Nanoparticles, Antony Adair
Open Access Theses & Dissertations
In this investigation we seek to identify the magnetic behavior of Ni0.5Zn0.5Fe2O4 nanoparticles though AC-susceptibility and DC-magnetization measurements. Powder x-ray diffraction was performed to determine the purity and average diameter ( ~ 9nm) of the particles. Aditionally, structure was confirmed by comparison through the International Centre for Diffraction Data's Powder Diffraction File [52] (PDF # 08-0234).
Zero-field cooled and field cooled DC magnetization measurements (bifurcation and blocking temperature), as well as M(H) hysteresis (below and above the blocking temperature) lead us to initially suggest that the material may in fact be superparamagnetic. However, further investigation of the real AC susceptibility …
Characterization And Cytotoxic Assessment Of Ballistic Aerosolized Particulates For Tungsten Alloy Penetrators Interacting With Steel Targets, Brenda Ivette Machado
Characterization And Cytotoxic Assessment Of Ballistic Aerosolized Particulates For Tungsten Alloy Penetrators Interacting With Steel Targets, Brenda Ivette Machado
Open Access Theses & Dissertations
The aerosolized particulates produced during an impact of depleted uranium munitions can potentially contaminate extensive areas around the impact sites and cause a wide spectrum of civilian and military damage. Thus materials such as WHA have been prompted for consideration. The present research is concerned with the regular collection of aerosol particulates associated with ballistic WHA rod penetration into rolled homogeneous steel (RHA) or other related steel armor as armor plate sequences. Particulate size characterization via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) along with chemical compositions via energy dispersive spectroscopy (EDS) were the focus of this research. …
Microstructural Characterization Of Overaged Gtd-111 Hp Turbine Buckets, Oscar Quintero
Microstructural Characterization Of Overaged Gtd-111 Hp Turbine Buckets, Oscar Quintero
Open Access Theses & Dissertations
Superalloys are metallic materials that exhibit excellent mechanical strength and creep resistance at high temperatures. They have good surface stability and are corrosion resistant. Superalloys are mostly used in the aerospace industry, gas turbine engines and blades (hot zones of gas turbines), and where extreme heat is encountered. The focus of this research was on the GTD-111 Ni-base superalloy, which is a General Electric (GE) proprietary superalloy mostly used in gas turbine blades with the form of high pressure or first stage buckets. This alloys features better mechanical properties, creep resistance, and a higher stress rupture temperature than the commonly …
Additive Layer Manufacturing Of Ti-6al-4v By Electron Beam Melting From Powder Particles: Solid, Mesh And Foam Components Study, Sara M. Gaytan
Additive Layer Manufacturing Of Ti-6al-4v By Electron Beam Melting From Powder Particles: Solid, Mesh And Foam Components Study, Sara M. Gaytan
Open Access Theses & Dissertations
Additive Manufacturing by Electron Beam Melting Rapid Manufacturing is a technology that consists of the fabrication of a CAD design by melting powder particles in a layer by layer fashion. In this study, Ti-6Al-4V has been utilized to fabricate solid, mesh and foam components by EBM technologies. Powder analysis of Ti-6Al-4V was performed to obtain a better understanding of the porosity obtained by the system. After proper optimization of the machine, and porosity control, microstructural analysis was performed to the components already mentioned and correlated by transmission electron microscopy. Besides the microstructural analysis, tensile and hardness testing was performed to …
Failure Analysis And Materials Characterization Of Hip Implants, Amanda Marie Bastidos
Failure Analysis And Materials Characterization Of Hip Implants, Amanda Marie Bastidos
Open Access Theses & Dissertations
This research focused on the microstructural characterization and failure analysis of hip implant components. The main hip components analyzed were the femoral heads and the ultra-high molecular weight polyethylene (UHMWPE) liners. Previous research has shown that hip implants tend to fail by the PE liners due to adhesive and abrasive wear, delamination, and third body particles (metals, ceramics, and PE). The methods and procedures for analyzing the said failures consisted of non-destructive and destructive evaluations. Non-destructive evaluations included of techniques such as visual characterization and dye penetrant inspection (DPI)-which displayed macroscopic surface details and presented initial clues as to the …
Art In A New Light: Design And Assessment Of Illuminants To Reduce Photochemical Degradation Of Works Of Art, Monica Fabiola Delgado
Art In A New Light: Design And Assessment Of Illuminants To Reduce Photochemical Degradation Of Works Of Art, Monica Fabiola Delgado
Open Access Theses & Dissertations
The purpose of this research is to design the best lighting that will minimize long term photochemical degradation of Old Master Drawings and/or other works of art, while maintaining the patron's appreciation of the object's color and detail. The present approach is a technological refinement to the basic underlying earlier work on fluorescent lighting by W. A. Thornton, W.A. at General Electric1. Thin-film dielectric, multi-coating technology is used to create filters that eliminate ultraviolet light, near infrared light and significant unnecessary parts from the visible spectrum, thus maximizing the reduction in photochemical degradation, while maintaining optimal color rendering. Three interference …
High Temperature Oxidation Characteristics Of Nb-10w-Xcr Alloys, Maria Del Pilar Moricca
High Temperature Oxidation Characteristics Of Nb-10w-Xcr Alloys, Maria Del Pilar Moricca
Open Access Theses & Dissertations
The use of refractory metals in high temperature applications has been attractive for several years. Systems based on niobium represent a potential new generation of refractory materials systems because of their low density, high melting points, and strength at elevated temperatures. Despite these desirable characteristics, the widespread use of niobium-based alloys is limited because its oxidation resistance is still inadequate for structural applications. Understanding the oxidation kinetics of Nb-based alloys and the role of the different phases in the oxidation process is of crucial importance to improve the oxidation resistance of these materials.
The effect of Cr content on the …
Microstructural Characterization And Heat Treatment Of A-286 Turbine Buckets, Christopher Michael Bradley
Microstructural Characterization And Heat Treatment Of A-286 Turbine Buckets, Christopher Michael Bradley
Open Access Theses & Dissertations
A-286 is an iron-based superalloy used extensively in land-based gas turbines for 2nd stage (low pressure) buckets and 1st and 2nd stage wheels. Although A-286 may appear to some as just another austenitic stainless steel, its elevated temperature properties are attributed to ' precipitate structures, effective distributions of alloy carbides in the forms of M23C6, M6C and MC, and solid solution strengthening. Unfortunately over the course of these components service lives microstructural degradation develops in the form of η-phase formation. The presence of η-phase, especially in large quantities, can have a negative effect on stress rupture properties. Resistance to creep …
Effects Of Build Orientation, Aging, And Pre-Conditioning On Mechanical Properties For Stereolithography-Manufactured Astm Type I Specimens Using A Design Of Experiments Approach, Karina Puebla
Open Access Theses & Dissertations
With industry's growing focus on the rapid manufacturing (RM) of end-use products, rapid prototyping (RP) or layered manufacturing (LM) machines that were originally designed to build prototypes may now be required to build functional end-use products. To successfully accomplish the transition, the available materials utilized in RP must provide the performance required for RM. The specific technology used must also be capable of producing repeatable and reproducible parts in regards to mechanical and dimensional properties.
A design of experiments approach was performed to determine the effects of build orientation, aging, and pre-conditioning on the mechanical properties. To perform the investigations, …
Exploring Poly(Ethylene Glycol) As A Suitable Material For Peripheral Nerve Regeneration Scaffolds Manufactured By Stereolithography, Nubia Zuverza
Exploring Poly(Ethylene Glycol) As A Suitable Material For Peripheral Nerve Regeneration Scaffolds Manufactured By Stereolithography, Nubia Zuverza
Open Access Theses & Dissertations
One of the challenges in tissue engineering is to have spatial and temporal control over the biological elements within a scaffold used to guide regeneration for example of transected nerves. Some of the physical and chemical characteristics to regulate include incorporation of bioactive domains and release of chemical signals. This study presents the use of stereolithography (SL) to incorporate localized domains for cell adhesion in addition to include releasable nerve growth factor (NGF) in the process of building poly(ethylene glycol)diacrylate (PEGda) hydrogel scaffolds. Besides providing sites for cell attachment, an ideal nerve guidance conduit (NGC) should be able to release …
Influence Of Magnesium Nitrate On The Corrosion Performance Of Sol-Gel Coated Aa2024-T3 Aluminium Alloy, Rajath Varma, Brendan Duffy, John Cassidy
Influence Of Magnesium Nitrate On The Corrosion Performance Of Sol-Gel Coated Aa2024-T3 Aluminium Alloy, Rajath Varma, Brendan Duffy, John Cassidy
Articles
Traditional anti-corrosion technology has relied heavily on using reducible metal species, predominantly hexavalent chromium (Cr(VI)), for protecting reactive metal alloys such as aluminium which is extensively used in the aerospace sector. However, the impending changes in the use of Cr(VI) in Europe and the United States have forced aerospace manufacturers to examine alternative materials for protecting aluminium. One of the most promising alternatives being investigated are organosilane based sol-gels containing anticorrosion additives. In this work the anti-corrosion properties of magnesium (II) nitrate (Mg(NO3)2) as a inhibitor was investigated at different concentrations (0.1% - 1.0 wt %) in a methyltriethoxysilane (MTEOS) …
Electronic And Structural Properties Of Molybdenum Thin Films As Determined By Real Time Spectroscopic Ellipsometry, J. D. Walker, H. Khatri, V. Ranjan, Jian Li, R. W. Collins, S. Marsillac
Electronic And Structural Properties Of Molybdenum Thin Films As Determined By Real Time Spectroscopic Ellipsometry, J. D. Walker, H. Khatri, V. Ranjan, Jian Li, R. W. Collins, S. Marsillac
Electrical & Computer Engineering Faculty Publications
Walker, J.D., Khatri, H., Ranjan, V., Li, J., Collins, R.W., & Marsillac, S. (2009). Electronic and structural properties of molybdenum thin films as determined by real-time spectroscopic ellipsometry. Applied Physics Letters, 94(14). doi: 10.1063/1.3117222
Low-Temperature Growth Of Inn On Si(100) By Femtosecond Pulsed Laser Deposition, M. A. Hafez, H. E. Elsayed-Ali
Low-Temperature Growth Of Inn On Si(100) By Femtosecond Pulsed Laser Deposition, M. A. Hafez, H. E. Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
InN films were grown on Si(100) using femtosecond pulsed laser deposition. Laser induced breakdown of ammonia was used to generate atomic nitrogen for InN growth. An indium buffer layer was initially deposited on the Si substrate at low temperature followed by an InN intermediate layer. The crystal quality and surface morphology were investigated by reflection high-energy electron diffraction during growth and atomic force microscopy and x-ray diffraction after growth. The results showed that the In (2×1) initial buffer layer improved the quality of the InN film. High quality InN films were grown at a temperature of ∼350 °C.
Oxidation Modeling By Means Of Molecular Dynamics, Chaiyod Soontrapa
Oxidation Modeling By Means Of Molecular Dynamics, Chaiyod Soontrapa
UNLV Theses, Dissertations, Professional Papers, and Capstones
Oxidation modeling is normally engineered to study systems at macroscopic scales, mostly in analytical forms based on diffusion theories. The associated time scale is usually in months, days, or minutes, and the length scale is in the order of microns. In this dissertation, oxidation modeling is performed at atomistic scale with the time and length scales in picoseconds and angstroms, respectively, using molecular dynamics. Molecular dynamics simulations generate trajectories of each atom or particle in a system according to the laws of physics. Studying oxidations under the atomistic point of view can offer new insights on atomic behaviors and influencing …
Fracture Toughness, Crack-Growth-Rate And Creep Studies Of Alloy 276, Joydepp Pal
Fracture Toughness, Crack-Growth-Rate And Creep Studies Of Alloy 276, Joydepp Pal
UNLV Theses, Dissertations, Professional Papers, and Capstones
Austenitic nickel-base Alloy 276 had been proposed to be a candidate structural material within the purview of the nuclear hydrogen initiative program. A mechanistic understanding of high temperature tensile deformation of this alloy has already been presented in an earlier investigation. The current investigation has been focused on the evaluation of crack-growth behavior, fracture toughness, stress-corrosion-cracking and creep deformation of this alloy as functions of different metallurgical and mechanical variables. The results of crack-growth study under cyclic loading indicate that this alloy exhibited greater cracking tendency with increasing temperature at a constant load ratio (R). However, the effect of temperature …
Tensile Strength And Failure Criterion Of Analog Lithophysal Rock, James A. Nott
Tensile Strength And Failure Criterion Of Analog Lithophysal Rock, James A. Nott
UNLV Theses, Dissertations, Professional Papers, and Capstones
This project determines the tensile strength of lithophysal analog rock and presents failure criteria that can be used by geotechnical engineers to evaluate underground structures in rock. The physical and mechanical properties that are related to the failure criterion, such as porosity, compressive strength and modulus of elasticity, are also discussed. Experimental tensile tests were made using direct uniaxial and indirect Brazilian tests. Three 4-inch specimens were fabricated and tested in direct uniaxial tensile tests using Hydro-Stone TB. The results showed that the elastic tensile modulus of elasticity was within two percent of existing data for the compressive modulus of …
Effects Of Mechanical And Metallurgical Variables On Creep, Fracture Toughness And Crack Growth Behavior Of Alloy 617, Muhammad Hasibul Hasan
Effects Of Mechanical And Metallurgical Variables On Creep, Fracture Toughness And Crack Growth Behavior Of Alloy 617, Muhammad Hasibul Hasan
UNLV Theses, Dissertations, Professional Papers, and Capstones
Nickel base Alloy 617 has been identified to be a suitable structural material for heat exchanger applications in both hydrogen and electricity generation using nuclear heat. A maximum operating temperature of 950°C has been specified by department of energy (DOE) for both applications to achieve a maximum possible efficiency. Therefore, an extensive investigation has been pursued to evaluate time-dependent-deformation (Creep) of this alloy as functions of temperature and applied load. The results indicate that this alloy exhibited severe creep deformation, characterized by development of an instantaneous tertiary creep region at 850 and 950°C under applied stresses corresponding to its 35% …
Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann
Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann
UNLV Theses, Dissertations, Professional Papers, and Capstones
One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.
We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …
Synthesis Of Surface Composites Using Friction Stir Processing, Bharat Gattu
Synthesis Of Surface Composites Using Friction Stir Processing, Bharat Gattu
Masters Theses
"Composite materials have an edge over monolithic materials due to higher strength/stiffness - to - density ratios, improved fatigue and wear resistance and better high temperature properties. Surface composites provide improved tribological properties such as wear resistance, friction coefficient and corrosion resistance. Friction stir processing (FSP) which originated from friction stir welding (FSW - a method for joining aluminum alloys) is a solid state technique to modify the microstructure of the alloys. During FSP the frictional heat generated at the tool - work piece interface plasticizes the material allowing it to flow around the pin. The combined effect of the …