Materials Science and Engineering Commons^™

Interface Reaction Induced Stress Development In An Aluminum Thin Film Copper Bulk Plate Diffusion Couple, Michael Codie Mishler

Material Science and Engineering Theses - Archive

This thesis investigates the mechanism of the interface reaction induced intermetallic phase formation (IMC) and its impact on the interface reliability in Al-Cu diffusion couple pairing. This study is motivated by the accelerated failure experiments in lead frame to integrated circuit (IC) package wire-bonds using copper (Cu) wire and aluminum (Al) bond-pad that have shown failure most often occurs at the interface of the intermetallic compound (IMC) γ2-phase (Cu9Al4). In order for simulative investigation, we created a diffusion couple consisting of Cu bulk plate coated pure Al thin films with thickness of ~2µm. This configuration is adapted to resemble the …

Influence Of The Volume-Contact Area Ration On The Growth Behavior Of The Cu-Sn Intermetallic Phase, Venkatakamakshi Supraja Giddaluri

Material Science and Engineering Theses - Archive

Solder Joints play a very important role in electronic packaging industry by serving as mechanical support and provides integrity to the device. The increasing demand for high performance, environmental and economic feasibility and miniaturization led to the development of high density interconnects. With the reduction in the size/stand off height of the solder is the reliability issues in the surface mount assemblies and packaging structures under various rigorous environments. One of the most important impact factors that affect the solder joint reliability is the growth rate IMC formed between the solder and substrate. IMC formation is required to ensure good …

Solution Processed Optical Coatings For Solar Cell Applications, Rajesh Tummala

Material Science and Engineering Theses - Archive

In the recent past the demand for higher energy conversion efficiency of solar cells is on the rise. Extensive research is carrying out and many new methods have been proposed by changing either fabrication process or implementation of anti-reflection coatings. In this thesis, the solution processed omni directional anti-reflection coatings have been demonstrated on commercial amorphous silicon solar cells and on fabricated organic solar cells. A simple convective coating technique is utilized to deposit spherical silica micro-particles on the commercial amorphous silicon solar cells and on fabricated organic solar cells. In order to investigate the behavior of solar cells at …

Nanoparticle-Bridge Assay For Amplification-Free Electrical Detection Of Oligonucleotides, Manouchehr Teimouri

Material Science and Engineering Dissertations - Archive

The aim of this research is to investigate a highly sensitive, fast, inexpensive, and field-applicable amplification-free nanoparticle-based oligonucleotide detection method which does not rely on any enzymatic or signal amplification process. In this approach, target oligonucleotide strands are detected through the formation of nanoparticle satellites which make an electrical path between two electrodes. This method enables an extremely sensitive oligonucleotide detection because even a few oligonucleotide strands can form a single nanoparticle satellite which can solely generates an electrical output signal. Results showed that this oligonucleotide detection method can detect oligonucleotide single strands at concentrations as low as 50 femtomolar …

Material Changes Of Bone Following Ishcemia Of The Immature Femoral Head, Olumide O. Aruwajoye

Material Science and Engineering Dissertations - Archive

Legg-Calvé-Perthes disease (LCPD) is a childhood hip disorder resulting from the loss of blood flow to the femoral head. In severe cases of the disease, the femoral head can develop a flattening deformity; additionally, if the disease is diagnosed at a later stage, it leaves most patients to develop early osteoarthritis of the hip. Due to a lack of pathological specimen from patients, an experimental piglet model of femoral head ischemia was developed. The model closely follows the radiographic changes seen in LCPD patients, where there is subchondral fracture, resorption, and a flattening deformity of the femoral head. After ischemia, …

Effect On Mechanical Properties Of Aluminium Alloy Composites On Adding Ash As Reinforcement Material, Mohd Zafaruddin Khan, Mohd Anas, Ather Hussain, Md Irshadul Haque, Kamran Rasheed

Journal of Metals, Materials and Minerals

To produce Al-matrix cast particle composites, wettability of the ceramic particles by liquid Al is essential. To improve wettability of the solution, few elements such as Mg and Si are added into Al melt to incorporate the ceramic particles. The present investigation has been focussed on the utilization of abundant available industrial waste such as fly ash and bagasse ash in useful manner by dispersing it into Eutectic Al-Si alloy LM6 Containing 10.58% Si to produce composites by liquid casting route. The mechanical properties such as Brinell Hardness and Ultimate tensile strength has been investigated. The test results of the …

Effect Of Temperature Dropping During Solution Treatment In Rejuvenation Heat Treatment On Final Microstructures Of Udimet 520, Kritsayanee Saelor, Panyawat Wangyao

Journal of Metals, Materials and Minerals

Udimet 520 is a low precipitation hardened nickel-based superalloy, which is made to be turbine blades at high temperature. After long-term service, the microstructure of the turbine blades could be degraded, then the mechanical properties are worse than the new ones. The rejuvenation heat treatment of degraded turbine blades, which are made of cast Udimet 520, is following by solution treatment at 1,121C / 4 hours and then double aging processes, which include primary aging at 843 C / 24 hours and secondary aging at 760 C / 16 hours, respectively.However, in practical reheat treatment processes, the temperature during solution …

Mechanical Reliability Of Porous Low-K Dielectrics For Advanced Interconnect: Study Of The Instability Mechanisms In Porous Low-K Dielectrics And Their Mediation Through Inert Plasma Induced Re-Polymerization Of The Backbone Structure, Yoonki Sa

Material Science and Engineering Dissertations - Archive

Continuous scaling down of critical dimensions in interconnect structures requires the use of ultralow dielectric constant (k) films as interlayer dielectrics to reduce resistance-capacitance delays. Porous carbon-doped silicon oxide (p-SiCOH) dielectrics have been the leading approach to produce these ultralow-k materials. However, embedding of porosity into dielectric layer necessarily decreases the mechanical reliability and increases its susceptibility to adsorption of potentially deleterious chemical species during device fabrication process. Among those, exposure of porous-SiCOH low-k (PLK) dielectrics to oxidizing plasma environment causes the increase in dielectric constant and their vulnerability to mechanical instability of PLKs due to the loss of methyl …

A Platform For Fast Detection Of Let-7 Micro Rna Using Polyaniline Fluorescence And Image Analysis Techniques, Partha P. Sengupta

Master's Theses

The project describes a new strategy for transducing hybridization events through modulating intrinsic properties of the electroconductive polymer polyaniline (PANI). When DNA based probes electrostatically interact with PANI, its fluorescence properties are increased, a phenomenon that can be enhanced by UV irradiation. Hybridization of target nucleic acids results in dissociation of probes causing PANI fluorescence to return to basal levels. By monitoring restoration of base PANI fluorescence as little as 10^-11 M (10 pM) of target oligonucleotides could be detected within 15 minutes of hybridization. Detection of complementary oligos was specific, with introduction of a single mismatch failing to …

Designing Optical Properties In Infrared Glass, Benn Gleason

All Dissertations

Chalcogenide glasses (ChGs) are well-known for their attractive optical properties, such as high refractive index and transparency in across infrared wavelengths. ChGs also possess the ability to compositionally tune properties such as the refractive index, the thermo-optic coefficient, and other non-optical properties. Chalcogenide glasses with compositionally tailored physical and optical properties will provide optical designers with new materials necessary to create novel infrared imaging systems requiring new or expanded functionality. This dissertation has evaluated the relationship between glass composition, the resulting atomic structure, and resulting optical and thermo-optical properties, with specific focus on the infrared refractive index and the thermo-optic …

Effect Of Tig Welding Parameters On Strain-Age Cracking In Joining Nickel-Based Superalloy, Gtd-111 With Inconel 625, Athittaya Athiroj, Panyawat Wangyao

Journal of Metals, Materials and Minerals

Excellent mechanical properties at high temperature of nickel-based superalloys brought them to extensive application in severe operating conditions. However, the great mechanical properties deteriorate after long-term exposure to high temperature and it frequently causes failure of the component e.g. cracking. TIG welding is considered as an economical way to refurbish the minor damage component as replacement with new one is costly due to high material cost and complexity in manufacturing processes. Unfortunately, heat from welding that applies to the component may create new cracks during and after process from liquation and strain-age cracking. This phenomena is problem especially in precipitation-hardened …

Effect Of Ni On The Formability And Texture Of Hot Rolled Weathering Steel, Gadadhar Sahoo, I. S. Wani, S. B. Kumar, Balbir Singh, Atul Saxena, R. Basu

Journal of Metals, Materials and Minerals

Formability behavior in two grades of hot rolled low carbon weathering steel with varying nickel content i.e., SCR 1 (Fe-0.116P-0.018Ni) and SCR 2 (Fe-0.115P-0.34Ni), have been evaluated in relationship to microstructure, EBSD estimated orientation distribution function (ODF), special boundary nature, mechanical properties and formability parameters like tensile stain hardening exponent (n) and plastic anisotropy ratio (r). The alloy sample SCR 1 exhibited improved formability characteristics in terms of stain hardening exponent (n) and plastic anisotropy ratio (r). This was mainly attributed to relatively higher fraction of the ND//<111> orientation or the ? fibre texture component and increased presence of sigma …

Microstructure Based Finite Element Simulation Of Jco Forming Process For Pipeline X65, Wut Thianngoen, Saranya Kingklang, Vitoon Uthaisangsuk

Journal of Metals, Materials and Minerals

In recent years, strong increases in energy demand have become the most important issue in every section. High strength pipeline steels make large contribution to cost reduction for fuel transportation in oil and gas industries due to their great combination of optimal strength and toughness properties. Mechanical properties of pipeline steel tubes are significantly influenced by their microstructure characteristics, which in turn are controlled by the production. In this work, the JCO forming process of gas pipeline tube made of hotrolled steel grade X65 with ferrite/pearlite microstructure was investigated by means of a FE multiscale modeling approach. Three different scales …

Mechanical Properties Of Interpenetrating Phase Composites Using Open-Cell Al Foams With Natural Rubber And Polyethylene, Kunmutta Angamnuaysiri, Seksak Asavavisithchai

Journal of Metals, Materials and Minerals

Interpenetrating phase composites (IPCs) were produced by conventional casting process, in vacuum atmosphere, using open-cell Al foams as matrix, and filled with either natural rubber or polyethylene. Mechanical properties of IPCs strongly depends on types of polymeric phases. It is found that the IPCs with polyethylene show an increase in compressive strength as well as failure strain. However, a large decrease of compressive strength is observed in the IPCs with natural rubber, as a result of cracks along the interface between Al foam and the rubber. These cracks are distributed throughout foam structure in the IPCs.

Microstructure And X-Ray Diffraction Analysis Of Al-Cu Couples Diffused At High Temperature, Jaime Hinojosa-Torres, Juan Manuelaceves-Hernández, Andres Herrera-Vázquez, Victor Manuelcastaño-Meneses

Journal of Metals, Materials and Minerals

By employing a thermal field of 813 K, couples of Al with Cu were welded as consequence of the atomic diffusion. The periods of permanency inside the field were 200, 320 and 480 hours. After the periods of test, SEM observations show the formation of two contiguous plate likes (~15 to 30 micrometres, width) that they are in normal position to the concentration gradient. By utilizing elemental analyses and X-ray diffraction techniques one plate like was identified as the h2 phase (CuAl) and the other one as the q phase (CuAl2) of the aluminium-copper system. Immediate to the q plate …

Process Development For Compression Molding Of Hybrid Continuous And Chopped Carbon Fiber Prepreg For Production Of Functionally Graded Composite Structures, Corinne Marie Warnock

Master's Theses

Composite materials offer a high strength-to-weight ratio and directional load bearing capabilities. Compression molding of composite materials yields a superior surface finish and good dimensional stability between component lots with faster processing compared to traditional manufacturing methods. This experimental compression molding capability was developed for the ME composites lab using unidirectional carbon fiber prepreg composites. A direct comparison was drawn between autoclave and compression molding methods to validate compression molding as an alternative manufacturing method in that lab. A method of manufacturing chopped fiber from existing unidirectional prepreg materials was developed and evaluated using destructive testing methods. The results from …

Molecular Dynamics Simulation Of Force-Controlled Nanoindentation, Keaton Jaramillo

Mechanical Engineering Undergraduate Honors Theses

The aim of this honors research is to develop a force-controlled nanoindentation algorithm for molecular dynamics simulation. The algorithm was tested on Silicon using the Tersoff potential and Gold using the Embedded-Atom Method (EAM) potential. The effect of varying the damping parameters that adjust the system pressure and changing run length between force iterations is explored. The force-controlled algorithm was developed and shown to be working by correlating pop-in events shown in the force versus displacement (P-h) curves to visualization software showing phase transformation or dislocation events in the sample.

An Open-Source, Automated Chemical Vapor Deposition System For The Production Of 2d Materials, Dale Brown

Boise State University Theses and Dissertations

While interest in two-dimensional materials has exploded in recent years, the high cost of chemical vapor deposition (CVD) systems can act as a barrier to entry for some researchers interested in studying these materials. This thesis presents an open-source design for an automated CVD that can be built for a fraction of the cost of similarly capable commercial systems and that can easily be customized and expanded.With a CVD built as described,growth of high quality graphene and graphene foam is demonstrated.These results highlight the flexibility of the open-source design in producing a variety of nanomaterials, which are at the forefront …

Plastic Deformation And Effective Strain Hardening Coefficient Of Irradiated Fe-9wt%Cr Ods Alloy By Nano-Indentation And Tem, Corey Kenneth Dolph

Boise State University Theses and Dissertations

The objective of this study is to characterize changes in the yielding, and effective strain hardening coefficient of an oxide dispersion strengthened (ODS) alloy upon exposure to irradiation. It is well known that irradiation produces a supersaturation of defects, which alters the mechanical properties of a material. In order to engineer materials for use in advanced nuclear reactors, the long-term effects of neutron irradiation on mechanical performance must be understood. However, high-dose neutron exposure is often simulated using ion bombardment. Unfortunately, ion irradiation results in a shallow damage layer that prevents traditional bulk mechanical characterization methods from being utilized. A …

Effects Of Expected Service Life Exposures On The Functional Properties And Impact Performance Of An American Football Helmet Outer Shell Material, David E. Krzeminski

Dissertations

The purpose of this dissertation is to gain a greater scientific understanding of the changes in functional material properties and impact performance of an American football helmet outer shell material under expected service life exposures. The research goals are to (i) quantify chemical, physical, thermal, and mechanical degradation of an American football outer shell material under expected environmental conditions and (ii) develop a linear drop test impact protocol to employ expected on-field impact conditions to American football helmet components and a plaque-foam (i.e., shell-liner) surrogate. Overall, a step-wise progression of analysis was demonstrated to concurrently quantify and understand changes in …

Hybrid Aryl-Ether-Ketone And Hyperbranched Epoxy Networks, John Misasi

Dissertations

In this dissertation, relationships between chemical structures, cure kinetics and network architectures are correlated to bulk mechanical properties for novel, hybrid epoxy-amine networks. The work is split into two primary sections: the first is the synthesis and characterization of multifunctional glassy networks based on aryl-ether-ketone diamine curatives, while the second is based on the synthesis and characterization of hyperbranched epoxy polymers and their resulting networks.

Three aryl-ether-ketone (AEK) diamines of increasing molecular weights were synthesized and used to cure 4,4’-tetraglycidylether of diaminodiphenylmethane (TGDDM); the resulting networks were compared to 4,4’-diaminodiphenyl sulfone cured TGDDM. Architectural differences were created by varying cure …

Polyacrylonitrile Copolymers: Effects Of Molecular Weight, Polydispersity, Composition, And Sequencing On Thermal Ring-Closing Stabilization, Jeremy D. Moskowitz

Dissertations

Controlled polyacrylonitrile (PAN)-based carbon fiber precursors with defined molecular weights, polydispersities, compositions, and architectures have been prepared for their study on thermal ring-closing stabilization behavior. PAN and its copolymers of number average molecular weights exceeding 170,000 g/mol were successfully synthesized via low temperature reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerizations of PAN-based precursors were compared to conventional free radical solution polymerizations with a focus on the effects of molecular weight and polydispersity on structural evolution and cyclization efficiency. When RAFT polymerization was extended to copolymers, it was found that RAFT copolymers achieved greater cyclization intensities and improved thermal stability …

Development Of Dual-Cure Hybrid Polybenzoxazine Thermosets, Jananee Narayanan Sivakami

Dissertations

Polybenzoxazines are potential high performance thermoset replacements for traditional phenolic resins that can undergo an autocatalytic, thermally initiated ring - opening polymerization, and possess superior processing advantages including excellent shelf-life stability, zero volatile loss and limited volumetric shrinkage. The simplistic monomer synthesis and availability of a wide variety of inexpensive starting materials allows enormous molecular design flexibility for accessing a wide range of tailorable material properties for targeted applications. Despite the fact, once fully cured, benzoxazines are difficult to handle due to their inherent brittleness, leaving a very little scope for any modifications. The motivation of this dissertation is directed …

Electrolyte Optimization Study For Tio2 Nanotube Electrode In Sodium Ion Batteries, Richard Wendel Cutler

Boise State University Theses and Dissertations

Batteries are ubiquitous in daily life. Sodium-ion batteries have the potential to become inexpensive alternatives to the current market products such as Lithium-ion batteries. TiO₂ nanotubes have proven potential as an anode for Na-ion batteries. Electrolytes made by NaClO₄ salt and carbonate-based solvents make up commonly used electrolytes in sodium ion battery research. We used electrochemical and physical characterization tests to evaluate the optimum electrolyte for this anode material in the Na system. We determined that the ClO₄^- ion decomposes at the TiO₂ surface and promotes the formation of an unstable solid electrolyte interphase. A …

Spare Parts On Demand Using Additive Manufacturing : A Simulation Model For Cost Evaluation., Stefan Jedeck

Electronic Theses and Dissertations

Little is known about the impact of additive manufacturing in the spare part supply chain. A few studies are available, but they focus on specific parts and their applications only. A general model, which can be adapted to different applications, is nonexistent. This dissertation proposes a decision making framework that enables an interested practitioner/manager to decide whether using additive manufacturing to make spare parts on demand is economical when compared to conventional warehousing strategy. The framework consists of two major components: a general discrete event simulation model and a process of designing a wide range of simulation scenarios. The goal …

Construction Of An Initiated Chemical Vapor Deposition (Icvd) Reactor And Deposition Of Polytetrafluoroethylene (Ptfe) Thin Films Using Perfluoro-1-Octanesulfonyl Fluoride As The Initiator, Edgar Kiprop Kosgey

Graduate Theses/Dissertations

Initiated Chemical Vapor Deposition (iCVD) is a surface polymerization technique that is different from other traditional chemical vapor deposition (CVD) techniques. iCVD is carried under a vacuum without the use of solvents, therefore eliminating contaminations. An initiator and a monomer are metered into a vacuum reactor chamber. Inside the reaction chamber is an array of resistively heated filaments and a cooled substrate stage. Monomer species adsorb on to the cooled substrate surface underneath the filament array. The thermal energy from the resistively heated filaments breaks the bonds in the initiator molecule, generating free radicals. These generated free radicals chemisorb to …

The Influence Of Iron On Arctic Thule Migration Patterns, Alina T. Aquino

UNLV Theses, Dissertations, Professional Papers, and Capstones

Arctic scholars have yet to fully understand the reasons behind the migration of Thule culture from the western to the eastern Arctic. This rapid movement across such a vast area into environmentally diverse regions marks a critical period of cultural change that is usually summarized by two theoretical positions. Ecological theories postulated environmental changes placed selective pressures on traditional food sources that required Thule hunters to follow migrating prey. Theories that focused on material acquisition alternately proposed the Thule followed the trail of meteoric iron eastward into northwestern Greenland.

This research sought to examine the eastward Thule migration from another …

Chemical And Electronic Structure Of Surfaces And Interfaces In Cadmium Telluride Based Photovoltaic Devices, Douglas Arthur Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The surface and interface properties are of the upmost importance in the understanding, optimization, and application for photovoltaic devices. Often the chemical, electronic, and morphological properties of the films are empirically optimized, however when progress slows, a fundamental understanding of these properties can lead to breakthroughs. In this work, surfaces and interfaces of solar cell-relevant films are probed with a repertoire of X-ray analytical and microanalysis techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), X-ray emission (XES) spectroscopies, and atomic force (AFM) and scanning electron (SEM) microscopies.

Silicon-based devices currently dominate the solar market, which is rather inflexible …

Comparative Estimates Of Anthropogenic Heat Emission In Relation To Surface Energy Balance Of A Subtropical Urban Neighborhood, Changhyoun Park, Gunnar W. Schade, Nicholas D. Werner, David J. Sailor, Cheolhee Kim

Mechanical and Materials Engineering Faculty Publications and Presentations

Long-term eddy covariance measurements have been conducted in a subtropical urban area, an older neighborhood north of downtown Houston. The measured net radiation (Q*), sensible heat flux (H) and latent heat flux (LE) showed typical seasonal diurnal variations in urban areas: highest in summer; lowest in winter. From an analysis of a subset of the first two years of measurements, we find that approximately 42% of Q* is converted into H, and 22% into LE during daytime. The local anthropogenic heat emissions were estimated conventionally using the long-term residual method and the heat emission inventory approach. We also …

An Approach To Model Plastic Deformation Of Metallic Plates In Hypervelocity Impact Experiments, Shawoon Kumar Roy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Space structures are subjected to micro-meteorite impact at extremely high velocities of several kilometers per second. Similarly, design of military equipment requires understanding of material behavior under extremely high pressure and temperature. Study of material behavior under hypervelocity impact (HVI) poses many challenges since few researchers so far have approached this problem. Material models, equations of the state, and fracture mechanics are not well understood under these conditions.

The objective of this research is to present an approach for studying plastic deformation of metallic plates under HVI conditions. A two-stage light gas gun can be used to simulate these conditions …