Engineering Commons^™

Microstructure, Wetting Angle And Corrosion Of Aluminum-Silicon Alloys, Shvetashva Suri

Theses and Dissertations

In this study the effect of composition, surface roughness and water droplet size on contact angle and corrosion properties of cast Aluminum-Silicon alloys containing Si from 5% to 50% have been examined. The water contact angle was measured on a given sample using a goniometer. In addition, the effect of surface roughness and droplet size on contact angle has been measured for alloys at a fixed composition. The microstructures can be found in this report with sizes of primary and eutectic Silicon as well as inter-particle spacing between Silicon. Contact angle measurements are accompanied with a photographic validation of the …

Aesthetic Coatings For Concrete Bridge Components, Brent Kriha

Theses and Dissertations

This thesis evaluated the durability and aesthetic performance of coating systems for utilization in concrete bridge applications. The principle objectives of this thesis were: 1) Identify aesthetic coating systems appropriate for concrete bridge applications; 2) Evaluate the performance of the selected systems through a laboratory testing regimen; 3) Develop guidelines for coating selection, surface preparation, and application.

A series of site visits to various bridges throughout the State of Wisconsin provided insight into the performance of common coating systems and allowed problematic structural details to be identified. To aid in the selection of appropriate coating systems, questionnaires were distributed to …

Synthesis And Characterization Of Microporous And Mesoporous Zeolites From Flyash For Heavy Metal Removal From Wastewater, Saeed Golbad

Theses and Dissertations

Class F fly ash was hydrothermally modified in one- and two-step processes to prepare zeolites with enhanced adsorption characteristics. Highly crystalline X type zeolite and hydroxy sodalite were targeted as microporous and mesoporous zeolite and were successfully synthesized using fly ash precursor by adjusting Si/Al molar ratio in reaction mixture. The heavy metal removal performance of the obtained fly ash-based zeolites was investigated in batch Pb2+ adsorption experiments.

Lead (Pb2+) is a positively charged toxic pollutant that can be present in surface water and industrial wastewater and may cause harmful physiological effects to human. As a result, standards for water …

Corrosion Of Aluminum Current Collector In Cost Effective Rechargeable Lithium-Ion Batteries, Shengyi Li

Theses and Dissertations

Rechargeable lithium ion batteries (LIB) have been widely used as commercial energy storage systems for portable equipment, electronic devices and high power applications (e.g. electronic vehicles). One issue with the commercialized LIB is that expensive, highly toxic and flammable organic solvents are used in the electrolyte and the fabrication process of electrodes. The toxic organic based solvents increase the production cost and lead to significant safety concerns in the event of a battery overcharge or short circuit. The recent development of “green manufacturing” technology allows manufacturers to replace the organic solvents used in the cathode coating process by aqueous based …

High Temperature Oxidation Of Alumina Forming Cast Austenitic Stainless Steels Within An Environment Of Pure Steam, Elmer A. Prenzlow

Theses and Dissertations

Steam cracking of hydrocarbons in the petrochemical industry is a multibillion dollar industry. The processes performed in these plants create byproducts that negatively affect the integrity of stainless steel piping through high temperature corrosion. Alloys used presently in industry rely on the formation of chromium oxide (chromia) as a protective layer between the bulk metal pipe and chemical byproducts. However, chromia can become susceptible to attack from aggressive species such as carbon, water vapor, and sulfur compounds, thus creating a need for a better protection method.

A new series of austenitic stainless steels have been developed in recent years that, …

Representative Volume Element (Rve) Finite-Element Analysis (Fea) Of Al Metal-Matrix Composites, Yuzhe Cao

Theses and Dissertations

ABSTRACT

REPRESENTATIVE VOLUME ELEMENT (RVE) FINITE-ELEMENT ANALYSIS

(FEA) OF AL METAL-MATRIX COMPOSITES

by

Yuzhe Cao

The University of Wisconsin-Milwaukee, 2016

Under the Supervision of Professor Chang-Soo Kim

Metal matrix composites reinforced by particles (a.k.a particle reinforced metal matrix composites, PRMMCs) could be suitable for a large number of applications with their enhanced mechanical properties. These composites generally consist of a base metal filled with hard/strong particles of which physical and mechanical properties very different from those of the matrix. These particles are intended to improve the properties of the base material including wear resistance, damping properties, and mechanical strength. Aluminum …

Phase Sensitive Thermography Of Magnetostrictive Materials Under Periodic Excitations, Peng Yang

Theses and Dissertations

The use of giant magnetostrictive materials in actuator and sensor applications is still relatively new. Giant magnetostrictive materials, such as Terfenol-D, are unique in producing large deformation under a magnetic field. Applications of these materials in solid state actuators and transducers may require more knowledge on the interaction between geometry and material properties for a specific design. In order to gain more understanding of the magnetostriction mechanism, phase sensitive or lock-in thermography has been used to study Terfenol-D. Thermography is useful in that it allows for full field measurement of the surface of an object with a relatively simple setup. …

Rational Design Of Cathode Materials For High Performance Lithium-Sulfur Batteries, Xi Chen

Theses and Dissertations

Sulfur, one of most promising cathode candidates for next-generation lithium ion batteries, shows a limited cycling performance due to its shuttling effect, low conductivity, self-discharge and volume expansion during lithiation and delithiation process. According to the operation principles, failure mechanism, and recent progress on lithium-sulfur batteries, here we developed several scalable and rational synthesis methods for high performance cathode materials. We dissolved commercial sulfur to anhydrous ethylenediamine (EDA) to form an EDA-S precursor, and then we reduced the sulfur particles size at conductive carbon black substrate. The 70% theoretical capacity of sulfur cathode battery was obtained. We also melted commercial …

Advanced Self-Healing Polymer Composites For Wind Turbine Blades, Arun Kumar Koralagundi Matt

Theses and Dissertations

Wind energy is one of the prime sources of energy among the renewable sources of energy. Wind power has been one of the most promising sources of long-term, clean energy. Materials and design approach in commercial wind turbines have not seen a momentous change in the recent years. In this study, an intriguing bio-mimetic design approach is sought after, which is to heal damages as they arise in a composite material. Self-healing material systems in wind turbine blades have the potential to fulfill the requirement as an added safety mechanism to heal damages and prevent catastrophic failures. Effectively supplying healing …

Nano-Crystalline Metal Matrix Nano-Composites Reinforced By Graphene And Alumina: Effect Of Reinforcement Properties And Concentration On Mechanical Behavior, Meysam Tabandeh Khorshid

Theses and Dissertations

Metal matrix composites (MMCs) and Metal Matrix Nano-composites (MMNCs) are promising materials for a number of aerospace, defense, and automobile applications. Among all MMCs and MMNCs, aluminum is the most widely used matrix due to its low density coupled with high stiffness, high specific strength, high specific modulus and low thermal expansion coefficient. While high strengths have been shown in MMCs, they are known to have very limited ductility. However, there are indications that reducing reinforcement size to the nanoscale may improve strain to failure in addition to increase strength. Reducing grain size to the nanoscale has been found to …

Study Of Ceria Nanoparticles Synthesis And The Performance Of Nano-Ceria Coating For High Temperature Oxidation Resistance In Combustion Atmosphere, Lingke Mao

Theses and Dissertations

Ceria (CeO2 ) nanoparticles were synthesized by the microemulsion method with Bis(2-ethylhexyl) Sulfosuccinate Sodium Salt (AOT) as the surfactant. Stirring speed during synthesis was used to optimize the process and a precipitation process was applied to dilute the surfactant. The prepared ceria nanoparticles were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM). As the result, non-agglomerated and time-stable ceria nanoparticles were obtained with the average particles size of 2-3 nanometers. Stainless steel 316L substrates were coated by a dipping method with the help of a slide motor which provided constant speed and uniform coating layers. Both coated and …

The Effective Use Of Coal Combustion Products (Ccps) In Ashphalt Pavements, Clayton J. Cloutier

Theses and Dissertations

Hot-Mix Asphalt (HMA) is one of the most widely used construction materials. The National Asphalt Paving Association (NAPA) estimated that there are over 2.6 million miles of roadway surfaces paved in the United States and 94% of these roads are paved with asphalt. NAPA also estimates that approximately 550 million tons of asphalt worth over $30 billion a year is produced in the United States. At such a huge production rate, innovative solutions need to be developed so that asphalt pavements last longer and can also reduce the production and maintenance costs. Producing sustainable asphalt materials can provide for improved …

Synthesis And Performance Analysis Of Polyurethane Foam Nanocomposite For Arsenic Removal From Drinking Water, Faten Bakri Hussein

Theses and Dissertations

Water contamination by various heavy metal pollutants such as, Lead, Arsenic, Cadmium, and Mercury, have severe toxic effects on living organisms and humans. High concentrations of arsenic in drinking water cause serious damage to the central and peripheral nervous systems, as well as, the dermal, cardiovascular, gastrointestinal, and respiratory systems. Arsenic contamination of ground water poses a substantial concern in many countries throughout the world, including the United States.

Considerable research work, aimed at finding and developing various separation and treatment techniques, has been conducted over the past few decades. The conventional treatment methods of arsenic involve coagulation with ferric …

Nanostructured Organic/Inorganic Semicondutor Photovoltaics: Investigation On Morphology And Optoelectronics Performance, Aruna Wanninayake

Theses and Dissertations

Organic solar cell is a promising technology because of the versatility of organic materials in terms of tunability of their electrical and optical properties. In addition, their relative insensitivity to film imperfections potentially allows for very low-cost high-throughput roll-to-roll processing. However, the power conversion efficiency of organic solar cell is still limited and needs to be improved in order to be competitive with grid parity. This work is focused on the design and characterization of a new organic/inorganic hybrid device to enhance the efficiency factors of bilayer organic solar cells such as: light absorption, exciton diffusion, exciton dissociation, charge transportation …

In-Situ Synthesis Of Aluminum- Titanium Diboride Metal Matrix Hybrid Nanocomposite, Afsaneh Dorri Moghdam

Theses and Dissertations

Metal matrix nanocomposites (MMNC’s) are reported to have improved mechanical, thermal and electrical properties as compared to their respective base alloys. To date, these materials have been synthesized mainly by powder metallurgy or deformation processing. Solidification synthesis of MMNCs is a promising method, capable of economically producing large and complex shapes, however technical challenges including nanoparticle agglomeration, and poor interfacial strength have hindered the adoption of this technology. In-situ processing methods, in which the reinforcements are synthesized in liquid metals, typically via exothermic reactions offer the potential for improved dispersion and interfacial bonding between the reinforcement and the matrix, however …

Synthesis Of Lifepo4/C Cathode Nanomaterials For Lithium-Ion Batteries, Chao Cheng

Theses and Dissertations

Lithium-ion batteries have been widely used for many years. The wide application covers such as smart phones, laptops, digital cameras, MP3 players, and electric vehicles. Lithium-ion batteries have become the most important energy storage device in the future. For lithium-ion batteries, the performance of the cathode materials is one of the most important factors. In recent years, the cathode materials have been widely studied including LiCoO2, LiNiO2, LiMnO2, LiMn2O4 and phosphate etc. Among the olivine structure cathode materials, the LiFePO4 (LFP) displays an excellent electrochemical activity and a chemical stability which ensure a high safety. In order to better improve …

Effects Of Surface Topography And Vibrations On Wetting: Superhydrophobicity, Icephobicity And Corrosion Resistance, Rahul Ramachandran

Theses and Dissertations

Concrete and metallic materials are widely used in construction and water industry. The interaction of both these materials with water and ice (or snow) produces undesirable results and is therefore of interest. Water that gets absorbed into the pores of dry concrete expands on freezing and can lead to crack formation. Also, the ice accretion on concrete surfaces such as roadways can have disastrous consequence. Metallic components used in the water industry undergo corrosion due to contact with aqueous corrosive solutions. Therefore, it is desirable to make concrete water/ice-repellent, and to make metallic surfaces corrosion-resistant.

Recent advances in micro/nanotechnology have …