Engineering Commons^™

Spark Plasma Sintering Of Magnesium Titanate Ceramics, Suzana Filipović, Nina Obradović, William G. Fahrenholtz, Steven Smith, Miljana Mirković, Adriana Peleš Tadić, Jovana Petrović, Antonije Đorđević

Materials Science and Engineering Faculty Research & Creative Works

Magnesium titanate ceramics were prepared by reactive spark plasma sintering (SPS) at 1200 °C for 5 min. Prior to sintering, MgO and TiO₂ powders were mixed by high energy ball milling (HEBM) for 15, 30, or 60 min. The effect of milling time on phase composition was analyzed by X-ray diffraction (XRD) for milled powders and sintered specimens. The morphology of the sintered ceramics was investigated by scanning electron microscopy (SEM), while elemental distribution was determined by energy dispersive spectroscopy (EDS). The presence of the MgTi2O5 phase was detected in XRD and was confirmed by EDS analysis. Microcracking was …

Utilizing Waste Latex Paint Toward Improving The Performance Of Concrete, Mohamed Leithy, Eslam Gomaa, Ahmed A. Gheni, Mohamed Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, incorporating the waste latex paint (WLP) into the conventional concrete as a partial replacement of sand to improve its durability was investigated. The fresh and hardened characterizations, in addition to the durability of concrete, were examined. The slump test was used to evaluate the fresh properties, while the hardened properties were evaluated through the volume of voids and absorption rate, in addition to the compressive, splitting tensile, and flexural strengths tests. The durability performance was evaluated by the surface resistivity, bulk electrical resistivity, as well as freeze and thaw resistance tests. The results showed a reduction in …

An Accelerated Corrosion Test Method For Pre-Cracked Reinforced Concrete, Shahriar Abed

Civil Engineering Dissertations

Reinforced concrete (RC), a composite material combining the strength of concrete and the tensile strength of steel reinforcement, has significantly transformed the field of civil engineering and contributed to the advancement of modern infrastructure. Reinforced concrete structures are susceptible to deterioration over time despite their numerous advantages. One of the primary factors leading to the degradation of RC is the corrosion of steel reinforcement, primarily caused by exposure to aggressive environmental elements such as chloride ions, carbonation, and moisture. This dissertation aims to provide valuable insights into the accelerated corrosion behavior of steel bars embedded in concrete, considering factors such …

Nematocidal And Bactericidal Activities Of Green Synthesized Silver Nanoparticles Mediated By Ficus Sycomorus Leaf Extract, Dina Elkobrosy, Abdulaziz A. Al-Askar, Hamada El-Gendi, Yiming Su, Rokaia Nabil, Ahmed Abdelkhalek, Said Behiry

Civil and Environmental Engineering Faculty Publications

Nanoparticles effectively control most plant pathogens, although research has focused more on their antimicrobial than their nematocidal properties. This study synthesized silver nanoparticles (Ag-NPs) through a green biosynthesis method using an aqueous extract of Ficus sycomorus leaves (FS-Ag-NPs). The nanoparticles were characterized using SEM, TEM, EDX, zeta sizer, and FTIR. The TEM results showed that the synthesized NPs were nanoscale and had an average particle size of 33 ± 1 nm. The elemental silver signal at 3 keV confirmed the formation of Ag-NPs from an aqueous leaf extract of F. sycomorus. The FTIR analysis revealed the existence of several …

The Role Of Slip System Activation On Ni-Based Superalloy High Temperature Fatigue, Alexandru Lopazan

Doctoral Dissertations and Master's Theses

Nickel-based superalloys are used extensively in the aviation industry, particularly in aircraft engine components. These materials are desirable due to their high strength, resistance to creep, corrosive environment, and high temperature. It has been well documented that material fatigue is characterized by material microstructure, type of loading, and other parameters. Currently, research into the effects of fatigue on complex materials like nickel-based superalloys is being pursued. Previous research has found that preconditioning of Inconel 718 samples at 700 ℃ with 1.0% strain led to an improved fatigue life. It has been suggested that this could be caused by the activation …

Effect Of Mechanical Activation On Carbothermal Synthesis And Densification Of Zrc, Nina Obradović, Lun Feng, Suzana Filipović, Miljana Mirković, Darko Kosanović, Jelena Rogan, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

Zirconium carbide ceramics were prepared by carbothermal reduction of ZrO₂ and C that were mixed by high-energy ball milling. Powders were milled for times from 0 to 120 min in air. As milling time increased, the surface area of the powders increased, indicating significant particle size reduction. Milled powders were reacted at 1600 °C and then densified by spark plasma sintering at 2000 °C, which was sufficient to convert the starting powders to zirconium carbide. Unmilled powders did not reach full density. Milled powders reached full density, but ZrO₂ impurities were found for specimens prepared from powders milled …

Effect Of Size And Shape Parameters On Microstructure Of Additively Manufactured Inconel 718, Showmik Ahsan

Browse all Theses and Dissertations

Additive Manufacturing (AM) methods are promising in applications where complex part geometries, exotic materials and small lot sizes are required. Aerospace manufacturing stands to use AM methods extensively in the future, and frequently requires temperature- and corrosion-resistant alloy materials such as Inconel 718. However, the microstructural evolution of Inconel 718 during additive manufacturing is poorly understood and depends on part size and shape. We studied the microstructure of Inconel 718 parts manufactured by Laser Powder Bed Fusion in order to further elucidate these dependencies. Microstructural analysis, SEM imaging, EBSD scans and Microhardness testing were performed.

Development Of Corn Kernel-Based Biocomposite Films For Food Packaging Applications, Swastika Bera

Electronic Theses and Dissertations

Most of the current and active food packaging resources and methods are nonbiodegradable and nonrenewable therefore harmful to the environment. Due to this, alternate sources of food packaging materials are in high demand. In this study, a bio-composite film has been developed, with Corn kernel powder as fiber reinforcement which is mixed with gelatin, and lignin two biopolymers as the matrix. The effect of Corn Kernel (CK) reinforcement on the Gelatin/Lignin (G/L) matrix on mechanical and barrier properties has been studied. CK has shown great potential as reinforcement to natural polymer, gelatin, and lignin (G/L) for food packaging applications as …

Synthesis And Characterization Of Hybrid Catalysts For Fischer-Tropsch Jet Fuel Production, Jack M. Steinagel

Honors College Theses

Climate change is a major issue that our world is facing today. Finding renewable options for current infrastructure is paramount to solving this issue. Fischer-Tropsch synthesis of syngas from gasified biomass can produce renewable fuels that can be used in current conventional combustion engines. In order to make this process more industrially viable, a higher selectivity towards the desired range of liquid hydrocarbon products must be achieved. A novel way to do this is to introduce a catalyst to the Fischer-Tropsch reaction. The catalyst’s physical and chemical properties can promote chain growth of specific hydrocarbons. For the purpose of this …

Characterization Of 3d Printed Parts Containing Integrated Functionality Via Ultrasonically Embedded Wires, David Abraham Sepulveda

Open Access Theses & Dissertations

Material extrusion additive manufacturing has been widely adopted because it offers freedom of design, which allows complex geometry fabrication, and rapid prototyping. Interest in producing components with integrated functionality allowed forms of hybrid manufacturing to be developed such as the Multi3D system. This system produces parts with embedded components by combining additive, subtractive, soldering, dispensing, and embedding techniques. However, this involves pausing the printing process (which takes place in a controlled environment) and exposing it to ambient temperature where embedding takes places. In this research, the effect of embedding parts with 24 AWG copper for improved functionality was quantified mechanically. …

Mobile 3d Printing Of Rail Track Surface For Rapid Repai, Ershad Mortazavian

UNLV Theses, Dissertations, Professional Papers, and Capstones

The frequent replacement of worn rails on tracks brings an immense economic burden on the railroad industry, and also causes significant interruptions to railroad operation. Restoration of worn rails via additive manufacturing, i.e., 3D printing, can considerably reduce the associated maintenance costs.The scope of this dissertation is to utilize metal additive manufacturing (AM) technology to repair worn rails that are used in the U.S. railway transportation system (e.g. 75-lb/yd light transit rails, or 136-lb/yd heavy freight rails). More specifically, this study aims to understand the interactive mechanisms between the deposited materials and the high-carbon rail steel to identify and alleviate …

The Transportation Of Corrosion Products In Cementitious Material Under Chloride-Rich Environment, Yuzhou Wang

International Conference on Durability of Concrete Structures

Corrosion products, forming on steel bar in cementitious material, can lead to concrete cracking. Clear the transportation of corrosion products is of great significance to predict corrosion-induced structural deterioration. This study investigates the corrosion products in steel-reinforced concrete specimen. By Raman spectroscopy and SEM method, the chemical constituents and micromorphology of corrosion products at steel-concrete interface as well as those inside the pore of cement paste are investigated. The proportion of corrosion products filling into the cement paste is determined by EDTA titration method. The results reveal that corrosion products diffuse in forms of ion in solution under chloride-rich environment, …

Microstructure Variation And Empirical Fatigue Model Of Salt Rock Under Cyclic Loading, Qiang Zhang, Jun-Bao Wang, Zhan-Ping Song, Shi-Jin Feng, Yu-Wei Zhang, Tao Zeng

Rock and Soil Mechanics

No abstract provided.

Degradation Mechanisms Of Zinc-Air Batteries Used In Hearing Aid, Kelly Hunt, Mallorty Bates, Gerard Klint Simon, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Hearing aid devices are powered by the oxidation of zinc that occurs within zinc-air batteries. Zinc-air batteries have an average discharge time of 7 days. Therefore, hearing-aid devices need frequent battery replacement. In this paper, degradation mechanisms of zinc-air batteries investigated where a competition mechanism between zinc passivation and dendritic formation dictates the battery life. This research included exposure time from none to 9 days and to document dendritic growth with time. Scanning electron microscope images were taken to quantify the damage growth as well energy dispersive X-ray tests were conducted to comment on the composition changes. The results confirmed …

Characterization And Utilization Of Alkali-Activated Concrete For Sustainable Infrastructures, Eslam Gomaa

Doctoral Dissertations

“This study has investigated the feasibility of using locally available fly ashes (FAs) to synthesize alkali-activated concrete (AAC) for different structural and repair applications. Using AAC made of 100% FA reduces global CO2 emissions, saves energy, and decreases raw material consumption during the production process of ordinary Portland cement. Class C FAs, sourced from Labadie, Jeffery City, Kansas City, Thomas Hill, and Sikeston power plants in the state of Missouri, were used to synthesize the AAC. Sodium silicate (SS), Na2SiO3, and sodium hydroxide (SH), NaOH were used as the alkali activators. Slag, crumb rubber, and air-entraining admixture were used as …

Nanomechanical Characterization And Comparison Of Additively Manufactured Grcop-42 Alloy, Trupti Suresh Mali

Electronic Theses and Dissertations

In an aggressive thermomechanical environment, the superior mechanical as well as thermal properties of materials play an essential role. GRCop which is a copper-based alloy developed by NASA has the potential to fulfill the requirements necessary for hightemperature applications such as the combustion chamber of liquid rocket engines. The first alloy of this family, GRCop-84 (Cu-8 wt.% Cr-4 wt.% Nb) was discovered followed with the development of GRCop-42 (Cu-4 wt.% Cr, 2 wt.% Nb). The reduction in alloying element percentage enhanced thermal conductivity with less built time while maintaining the strength of the material. The conventional fabrication is replaced with …

Experimental Investigation Of Surface Resistivity Of Yttrium Stabilized Zirconium As A Thin Film, Matthew J. Melfi

Seton Hall University Dissertations and Theses (ETDs)

Solid Oxide Fuel Cells are devices that use electrochemical reactions to convert chemical energy from fuel to electricity. In comparison with coal power plants, a Solid Oxide Fuel Cell, produces a higher electrical conversion efficiency. However, at higher temperatures (1000°C) it creates a lower ionic conductivity, which limit the Solid Oxide Fuel Cells. When lowering the temperature, the ohmic resistance increases. In our research, an Yttrium Stabilized Zirconium layer will be produced from a fine dimple grain structure allowing high flow of oxygen mobility. This mobility increases ionic conductivity and decrease ohmic loss. The goal of our research is first …

A Method For Orientation Of Cellulose Nano Fibers For Addition Of Biological Nanoparticles And Tissue Integration, Joshua Hamilton

Honors College

The University of Maine is one of the world’s leading producers of cellulose nanofibers (CNF). This material has the power to revitalize the Maine paper industry. This has led to an abundance of labs on campus researching applications for the material. Active research activities at the University of Maine include industrial applications such as filtration, biodegradable packaging, building materials and niche health care applications. Niche health care applications include wicking pads for point of care diagnostics and tunable biomaterials ranging from dressings to implantable bone-like materials. Medical applications require an analysis of the biocompatibility of CNF.CNF is biocompatible in general: …

Investigation On Microstructure And Mechanical Properties Of Porous Structures Processed By Laser Powder Bed Fusion, Samarth Ramachandra

Mechanical and Aerospace Engineering Theses

Inconel 718 (i.e., IN718) is a prominent nickel-based, precipitation-hardening superalloy which exhibits exceptionally stable mechanical and corrosion resistant properties, even at temperature range of 650ºC to 700ºC, making it suitable for a wide range of applications such as aerospace, nuclear reactors, tooling, turbines, oil and gas applications. The high toughness and work hardening offered by this superalloy, however, greatly limits the choice of machinability. The presence of low levels of aluminum permits good weldability which further allows the use of laser-based additive manufacturing (AM) to efficiently fabricate IN718 parts without the limitations associated with conventional manufacturing methods. Thanks to AM …

Investigation Of The Microstructural And Mechanical Properties Of Selectively Laser Melted In718 Overhangs Fabricated Without Support Structures, Manjunath Hanumantha

Mechanical and Aerospace Engineering Theses

Additive manufacturing is a new manufacturing technology that allows for extreme design freedom as well as the simultaneous production of many parts with high complexities. IN718 is a high-strength, corrosion-resistant super alloy of nickel and chromium. It is ideal for high-end applications such as rocket nozzles and turbines because it can handle exceptionally high pressure and heat. Because of its high stiffness qualities, conventional manufacturing of complex IN718 geometries is challenging. Various fabrication techniques have been developed, and this study focuses on selective laser melting (SLM) because of its potential to produce near-perfect parts at a low cost when working …

Fabrication And Characterization Of Highly Ordered Aao Nanotubes, Anvar Khamidov, Farhod Hoshimov, Suvonkul Erkhanovich Nurmonov, Olim Ruzimuradov, Shavkat Mamatkulov

CHEMISTRY AND CHEMICAL ENGINEERING

Investigated the electrochemical synthesis and characterized of a nanometer scale porous anodic aluminum oxide (AAO) membranes with a mean pore diameter about of 80-100 nm. The anodizing process done by varying the anodizing temperature from 20 °C to 25 °C. The membranes exhibit interesting properties such as controllable pore diameters, periodicity and density distribution. These properties can preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The surface features of the nanometer scale membrane such as pore density, pore diameter and interpore distance were quantified using scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM …

Effect Of Different Cooling Conditions On Physical And Mechanical Properties Of High-Temperature Sandstone, Ai-Bing Jin, Shu-Liang Wang, Yu-Dong Wei, Hao Sun, Li-Chang Wei

Rock and Soil Mechanics

Rock engineering may be subjected to high temperature environment. Different cooling methods of high-temperature rock often lead to significant changes in the physical and mechanical properties of the rock, which will have an important impact on the stability and permeability of rock engineering. Magnetic resonance imaging (MRI), scanning electron microscope (SEM) and uniaxial compression test were used to study the porosity, pore size distribution, peak strength, peak strain, stress-strain relationship and microstructure changes of five temperatures for sandstone samples at 100, 300, 500, 600 and 800℃ under two cooling methods (natural cooling and water cooling). The test results show that: …

Fabrication And Analysis Of High-Performance Thermochemically Densified Wood, Victor Arulappan Pushparaj

Browse all Theses and Dissertations

While wood construction may be as ancient as humanity itself, wood remains one of the most utilized structural materials because of it’s availability, low cost, durability, surprisingly high specific mechanical properties, and renewability. Recent research into wood-based materials has focused on strategies for enhancing the strength and stiffness of as-grown materials. We fabricated densified wood by thermochemically treating raw white oak wood in Na2SO3 and NaOH solutions, followed by compressing the treated wood at 5MPa at high temperature. Treating the raw wood in NaOH and Na2SO3 cleaves the alpha-O-4 ether bond and beta-O-4 ether bonds, thus dissolving most of the …

Fabrication Of Black Silicon Via Metal-Assisted Chemical Etching—A Review, Mohammad Yasir Arafat, Mohammad Aminul Islam, Ahmad W. B. Mahmood, Fairuz Abdullah, Mohammad Nur-E-Alam, Tiong Sieh Kiong, Nowshad Amin

Research outputs 2014 to 2021

The metal-assisted chemical etching (MACE) technique is commonly employed for texturing the wafer surfaces when fabricating black silicon (BSi) solar cells and is considered to be a potential technique to improve the efficiency of traditional Si-based solar cells. This article aims to review the MACE technique along with its mechanism for Ag-, Cu- and Ni-assisted etching. Primarily, several essential aspects of the fabrication of BSi are discussed, including chemical reaction, etching direction, mass transfer, and the overall etching process of the MACE method. Thereafter, three metal catalysts (Ag, Cu, and Ni) are critically analyzed to identify their roles in producing …

Functionalizing Ceramic Matrix Composites By The Integration Of A Metallic Substructure With Comparable Feature Size, Elizabeth Pierce Heckman

Browse all Theses and Dissertations

A metallic network has been embedded in a silicon carbide fiber– silicon carbide (SiC) matrix ceramic composite (CMC) in order to combine the functional properties of the metal and the structural properties of the CMC. The processing of the composite involves iterative pre-ceramic polymer infiltration and heating to temperatures at 1100°C. The metallic structure embedded in the CMC must retain its unique properties during processing and cannot convert to a silicide or carbide resulting from diffusion of Si and C species from the SiC matrix. To gain an understanding of the diffusion process, a fully processed CMC with tungsten, tantalum, …

Development And Optimization Of Imaging And Image Quantification Techniques For Tissue-Engineered Blood Vessel Mimics, Ashley Turcott

Master's Theses

Blood vessels mimics (BVMs) are tissue-engineered blood vessels used to test vascular devices in an environment that mimics some simple anatomical factors of native blood vessels. It is important to accurately and consistently assess tissue-engineered blood vessels, although there is currently a lack of standardization in Cal Poly’s Tissue Engineering Lab and in the entirety of the field. The goal of this thesis was to develop and optimize imaging and image quantification techniques for tissue-engineered blood vessels.

The first aim of this thesis optimized and compared imaging and assessment techniques for electrospun scaffolds. Images from different SEMs were compared to …

Experiment Of Mesostructure And Hydrologic Characteristics Of Weakly Cemented Soft Rocks In Western China, Zhang Jiafan, Cheng Shufan, Wang Huan, Gao Zhuang, Zhou Feiwen, Zhou Hongwen

Coal Geology & Exploration

In order to accurately grasp the hydrologic characteristics of weakly cemented soft rocks in western China, the hydraulic and mechanical properties of red sandstone collected from northern Shaanxi mining area were tested. Based on the scanning image of scanning electron microscope(SEM), the mesostructural characteristics of the rocks were analyzed, and the relationship between the mesostructure of rocks and its macroscopic hydrologic characteristics was established. The results show that red sandstone has obvious characteristics of water saturation and water absorption and expansion, and its softening coefficient is 0.64. Under the action of pressure water erosion and dry and wet cycle, the …

Influence Of Separator Surface Charge On The Nucleation And Penetration Dynamics Of Metal Electrodes In Concentrated Electrolytes, Sikuang Wang

McKelvey School of Engineering Theses & Dissertations

No abstract provided.

Mechanical Properties Of Permanent Foaming Fixatives For Deactivation & Decommissioning Activities, Tristan Maximilian Simoes-Ponce

FIU Electronic Theses and Dissertations

The Department of Energy is investigating fixative technologies that encapsulate and/or immobilize residual contamination in voids during deactivation and decommissioning (D&D). These technologies must have adequate mechanical and adhesion properties to withstand seismic activity that may occur. One solution is the implementation of polyurethane foams used as permanent foaming fixatives (PFF), specifically intumescent foams that contain expandable graphite, making them fire resistant when exposed to extreme heat conditions.

Tensile, compression, seismic, and tensile adhesion testing was done on six commercial-off-the-self polyurethane foams to determine if the expandable graphite and other filler intumescent technologies improve its mechanical limits. It was found …

Fracture Toughness Analysis Of Epoxy-Recycled Rubber-Based Composite Reinforced With Graphene Nanoplatelets For Structural Applications In Automotive And Aeronautics, Alaeddin Burak Irez, Emin Bayraktar, Ibrahim Miskioglu

Michigan Tech Publications

This study proposes a new design of lightweight and cost-efficient composite materials for the aeronautic industry utilizing recycled fresh scrap rubber, epoxy resin, and graphene nanoplatelets (GnPs). After manufacturing the composites, their bending strength and fracture characteristics were investigated by three-point bending (3PB) tests. Halpin-Tsai homogenization adapted to composites containing GnPs was used to estimate the moduli of the composites, and satisfactory agreement with the 3PB test results was observed. In addition, 3PB tests were simulated by finite element method incorporating the Halpin-Tsai homogenization, and the resulting stress-strain curves were compared with the experimental results. Mechanical test results showed that …