Materials Science and Engineering Commons^™

Experimental And Theoretical Evaluation Of In-Depth Damage Distribution In Sawn Silicon Wafers, Srinivasamurthy Devayajanam

Dissertations

As-sawn silicon wafers have surface damage that needs to be removed before any further processing into solar cells. This damage distribution can vary with cutting parameters such as wire size, slurry particle/diamond grit size, and wire usage. To date, there is no simple way to measure the degree of damage, damage depth, and damage distribution. But, this information is needed by the wafer manufacturers as well as solar cell manufacturers.

A technique based on sequential etching of silicon wafers and minority carrier lifetime (τ_eff) measurements is used to determine damage depth. In this technique, samples are sequentially etched …

Thermoelectric Properties Of Silicon-Germanium Alloys, Aniket Annasaheb Maske

Theses

Direct energy conversion from thermal to electrical energy, based on thermoelectric effects, is attractive for potential applications in waste heat recovery and environmentally friendly refrigeration. The energy conversion efficiency of thermoelectric devices is related to the thermoelectric figure of merit ZT, which is proportional to the electrical conductivity, the square of the Seebeck coefficient, and the inverse of the thermal conductivity. Currently, the low ZT values of available materials restrict the large scale applications of this technology. Recently, however, significant enhancements in ZT have been reported in nanostructured materials such as super-lattices mainly due to their low thermal conductivities. According …

Understanding Bulk Behavior Of Particulate Materials From Particle Scale Simulations, Xiaoliang Deng

Dissertations

Particulate materials play an increasingly significant role in various industries, such as pharmaceutical manufacturing, food, mining, and civil engineering. The objective of this research is to better understand bulk behaviors of particulate materials from particle scale simulations.

Packing properties of assembly of particles are investigated first, focusing on the effects of particle size, surface energy, and aspect ratio on the coordination number, porosity, and packing structures. The simulation results show that particle sizes, surface energy, and aspect ratio all influence the porosity of packing to various degrees. The heterogeneous force networks within particle assembly under external compressive loading are investigated …

Development Of Pvdf Membrane Nanocomposites Via Various Functionalization Approaches For Environmental Applications, Douglas M. Davenport, Minghui Gui, Lindell E. Ormsbee, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

Membranes are finding wide applications in various fields spanning biological, water, and energy areas. Synthesis of membranes to provide tunable flux, metal sorption, and catalysis has been done through pore functionalization of microfiltration (MF) type membranes with responsive behavior. This methodology provides an opportunity to improve synthetic membrane performance via polymer fabrication and surface modification. By optimizing the polymer coagulation conditions in phase inversion fabrication, spongy polyvinylidene fluoride (PVDF) membranes with high porosity and large internal pore volume were created in lab and full scale. This robust membrane shows a promising mechanical strength as well as high capacity for loading …

Free And Open-Source Control Software For 3-D Motion And Processing, Bas Wijnen, G. C. Anzalone, Amberlee S. Haselhuhn, Paul G. Sanders, Joshua M. Pearce

Department of Materials Science and Engineering Publications

RepRap 3-D printers and their derivatives using conventional firmware are limited by: 1) requiring technical knowledge, 2) poor resilience with unreliable hardware, and 3) poor integration in complicated systems. In this paper, a new control system called Franklin, for CNC machines in general and 3-D printers specifically, is presented that enables web-based three dimensional control of additive, subtractive and analytical tools from any Internet connected device. Franklin can be set up and controlled entirely from a web interface; it uses a custom protocol which allows it to continue printing when the connection is temporarily lost, and allows communication with scripts.

Influence Of Oxygen Concentration On The Performance Of Ultra-Thin Rf Magnetron Sputter Deposited Indium Tin Oxide Films As A Top Electrode For Photovoltaic Devices, Jephias Gwamuri, Murugesan Marikkannan, J. Mayandi, Patrick Bowen, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The opportunity for substantial efficiency enhancements of thin film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic (PV) cells using plasmonic absorbers requires ultra-thin transparent conducting oxide top electrodes with low resistivity and high transmittances in the visible range of the electromagnetic spectrum. Fabricating ultra-thin indium tin oxide (ITO) films (sub-50 nm) using conventional methods has presented a number of challenges; however, a novel method involving chemical shaving of thicker (greater than 80 nm) RF sputter deposited high-quality ITO films has been demonstrated. This study investigates the effect of oxygen concentration on the etch rates of RF sputter deposited ITO films to …

Late Morning Concurrent Sessions: Innovations In Aviation Technologies: Presentation: Relative Material Loss: A Methodology For Assessing Island Airport Steel Marine Bulkheads, Robert Ernsting, Constantine M. Koursaris

Aviation / Aeronautics / Aerospace International Research Conference

A July 2015 report from the Airports Council International – North America (ACI-NA) states “U.S. airports are long overdue for [a] major structural improvement projects. Most U.S. airports are aging, … and because of budgetary restrictions, they’re not aging well.”(Garcia and Clampet, 2015). The average US age is 40 years old with the youngest (Denver International) recently turning 20 years old. As airports continue to age, airport commissioners will struggle to find creative ways to either fund airport replacements or extend the service life of existing airport facilities (commonly referred to as service life extension projects or SLEP). Due to …

High-Efficiency Solar-Powered 3-D Printers For Sustainable Development, Jephias Gwamuri, Dhiogo Franco, Khalid Khan, Lucia Gauchia, Joshua M. Pearce

Michigan Tech Publications, Part 1

The release of the open source 3-D printer known as the RepRap (a self-Replicating Rapid prototyper) resulted in the potential for distributed manufacturing of products for significantly lower costs than conventional manufacturing. This development, coupled with open source-appropriate technology (OSAT), has enabled the opportunity for 3-D printers to be used for sustainable development. In this context, OSAT provides the opportunity to modify and improve the physical designs of their printers and desired digitally-shared objects. However, these 3-D printers require electricity while more than a billion people still lack electricity. To enable the utilization of RepRaps in off-grid communities, solar photovoltaic …

Mechanical Self-Assembly Of A Strain-Engineered Flexible Layer: Wrinkling, Rolling, And Twisting, Zi Chen, Gaoshan Huang, Ian Trase, Xiaomin Han, Yongfeng Mei

Dartmouth Scholarship

Self-shaping of curved structures, especially those involving flexible thin layers, is attracting increasing attention because of their broad potential applications in, e.g., nanoelectromechanical andmicroelectromechanical systems, sensors, artificial skins, stretchable electronics, robotics, and drug delivery. Here, we provide an overview of recent experimental, theoretical, and computational studies on the mechanical self-assembly of strain-engineered thin layers, with an emphasis on systems in which the competition between bending and stretching energy gives rise to a variety of deformations, such as wrinkling, rolling, and twisting. We address the principle of mechanical instabilities, which is often manifested in wrinkling or multistability of strain-engineered thin layers. …

Reversible Plastic Events During Oscillatory Deformation Of Amorphous Solids, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The effect of oscillatory shear strain on nonaffine rearrangements of individual particles in a three-dimensional binary glass is investigated using molecular dynamics simulations. The amorphous material is represented by the Kob-Andersen mixture at the temperature well below the glass transition. We find that during periodic shear deformation of the material, some particles undergo reversible nonaffine displacements with amplitudes that are approximately power-law distributed. Our simulations show that particles with large amplitudes of nonaffine displacement exhibit a collective behavior; namely, they tend to aggregate into relatively compact clusters that become comparable with the system size near the yield strain. Along with …

System And Method For Identifying Electrical Properties Of Integrate Circuits, Mary Y. Lanzerotti

AFIT Patents

A new method for displaying electrical properties for integrated circuit (IC) layout designs provides for improved human visualization of those properties and comparison of as designed layout design parameters to as specified layout design parameters and to as manufactured layout parameters. The method starts with a circuitry as designed layout in a first digital format, extracts values for electrical properties from that circuitry as designed layout then annotates those values back into the first digital format. The annotated circuitry as designed layout is then converted from the first digital format to a second digital format that can be converted to …

Paper Core Feeder System, Sergio Flores Velez

All Undergraduate Projects

Paragon Films has always strived to increase productivity and decrease waist within their company. The plant located in Union Gap, Washington currently has two production lines operating 24/7 managed by 2 to 3 people. The heavy line produces 5000 to 10000 revolutions per roll. This production line has a three part system that automatically feeds the paper cores to the spool shafts to roll the films. Therefore, the employees during that shift do not have to worry about filling up the bin very often. On the other hand, the second production line, which produces the hand films, does not have …

Conversion Casting: Adapter Hub, Joseph M. Coup

All Undergraduate Projects

The concept of conversion casting makes manufacturing major components much more efficient with regards to time and cost. The conversion cast of the adapter hub used in the Victair Mistifier is a major component that requires 8 hours to machine. The existing hub starts from steel stock and then that block of steel is placed into a CNC machine and coded in to create the adapter hub. The manufacturing method changes to a casting for the adapter hub will create a replicated part that requires 1.5 hours of post machining. The intricate design makes a conversion to casting more effective …

State-Of-The-Art Review Of Cathodic Protection For Reinforced Concrete Structures, Aimee Byrne, Niall Holmes, Brian Norton

Articles

Cathodic protection (CP) limits the corrosion of a metal surface by making it the cathode of an electrochemical cell. This can be achieved either by using a more active sacrificial anode to create a driving current, or by using inert anodes and impressing a current onto the cathode surface using an external direct current (DC) source. Impressed current cathodic protection (ICCP) is preferred where widespread protection is required, particularly in reinforced concrete structures. ICCP needs a constant DC power supply that is usually provided through a grid connection or independent generators. This paper presents the currently available CP systems for …

Multi-Use Fireline Handtool, Bruce W. Bernard Jr

All Undergraduate Projects

A wildland firefighter is a valuable resource to protecting public lands and managing fuels. The many hand tools used by firefighters aid in their ability to complete any required tasks effectively. Several of the tools available are specially purposed for individually grubbing, scraping, or liming. A small squad of firefighters could become a more effective resource if the tools they carried could perform several of these purposes as one single tool. To improve the effectiveness of an individual on the fireline a multi-use hand tool was designed to include an axe for liming and a heavy duty scraper for grubbing …

Synthesis And Characterization Of Kesterite Cu2znsns4 (Czts) Thin Films For Solar Cell Application, Mohamed M.A. Abusnina

Electronic Theses and Dissertations

The quaternary compound Cu₂ZnSnS₄ (CZTS) gained considerable attention in the last decade due to its potential as an active-layer semiconductor for low-cost thin-film solar cells. The material is composed of nontoxic and Earth-abundant constituents, has optical properties suitable for photovoltaic application, and can be synthesized using a wide variety of methods.

Polycrystalline CZTS was grown in this work using vacuum-based deposition to first deposit metal films (precursors) of Cu, Zn, and Sn. In a subsequent step, the precursors underwent an annealing treatment in sulfur vapor environment (sulfurization) to form CZTS. Using sputtering, a physical vapor deposition (PVD) …

Aging Assessment Of High Voltage Single Component Room Temperature Vulcanized Silicone Rubber (Rtv-1) Subjected To Aqueous Salt, Monika Bleszynski

Electronic Theses and Dissertations

Single component room temperature vulcanized (RTV-1) silicone based caulk used in high voltage insulators and other applications is frequently subjected to environmental pollutants. Aging of RTV-1 silicone rubber is the result of various stressors, including environmental aging conditions such as UV, acid, and salt exposure from ocean mist. Loss of hydrophobicity due to damage of the hydrophobic methyl groups, as well as loss of mechanical strength due to depolymerization via hydrolysis as a result of aqueous salt exposure were the two main factors of material aging assessed in this work. Multiple RTV-1 formulations were initially assessed for resistance to aging …

Properties Of Partially Stabilized Zirconia Components Fabricated By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Ming Leu, Gregory Hilmas, Jeremy Watts

Faculty Publications, Mechanical Engineering

The Ceramic On-Demand Extrusion (CODE) process is a novel additive manufacturing process for fabricating dense ceramic components from aqueous pastes of high solids loading. In this study, 3 mol% Y2O3 stabilized tetragonal zirconia polycrystal (3Y-TZP) parts were fabricated using the CODE process. The parts were then dried in a humidity controlled environmental chamber and sintered under atmospheric pressure. Mechanical properties of the sintered parts were examined using ASTM standard test techniques, including density, Young’s modulus, flexural strength, Weibull modulus, fracture toughness and Vickers hardness. The microstructure was analyzed, and grain size was measured using scanning electron microscopy. The results compared …

Case Studies Of Cavity And External Wall Insulation Retrofitted Under The Irish Home Energy Saving Scheme: Technical Analysis And Occupant Perspectives, Aimee Byrne, Gerard Byrne, Garrett O'Donnell, Anthony Robinson

Articles

The residential sector represents 27% of primary energy consumption in Ireland. This paper examines the case study of the Irish government’s national grant scheme to encourage energy efficiency retrofit in private housing. That is the Home Energy Saving (HES) Scheme, later rebranded the Better Energy: Homes (BEH) Scheme. The methodology involved monitoring several homes immediately before and after retrofit alongside discussions with occupants. The examination focused on specific measures commonly introduced through the HES/BEH programme − cavity and external wall insulation. It has been found that a significant decrease in heat loss through the walls was measured in all cases. …

A Comparative Study Of Zn-Mn Electrodeposition From Deep Eutectic Solvents And Aqueous Electrolytes, Jelena Bajat, Mihael Bucko, David Culliton, Tony Betts

Conference Papers

The production of Zn-Mn coatings with high Mn and low oxygen content from additive free choline chloride/urea deep eutectic solvent (DES) is reported in this work. Alloy coatings containing high Mn contents (~30 at.% Mn) show the highest corrosion resistance amongst zinc alloys [1]. However, in order to obtain Mn-rich deposits on steel from a simple aqueous bath, a significant cathodic polarization or high deposition current density is necessary. Under such conditions, the Zn 2+ reduction reaction is under diffusion control, leading to the formation and growth of dendrites. In addition intensive hydrogen evolution significantly reduces the current efficiency, often …