Materials Science and Engineering Commons^™

สัมประสิทธิ์การแพร่ของไฮโดรเจนผ่านผิวเคลือบทองคำ และผิวเคลือบนิกเกิลบนเหล็กกล้าไร้สนิม Aisi 304, กฤตยชญ์ วรรณโพธิ์กลาง

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้เกิดจากพื้นฐานความคิดว่าชั้นเคลือบโลหะบนเหล็กกล้าไร้สนิม AISI 304 เป็นชั้นต้านทานการแพร่ของไฮโดรเจนเพื่อชะลอการแตกร้าวจากการช่วยของไฮโดรเจน (Hydrogen Assisted Cracking, HAC) ในงานวิจัยใช้ขั้นตอนการดำเนินงานตามมาตรฐาน ASTM G148-97 ตรวจวัดสัมประสิทธิ์การแพร่ไฮโดรเจนประสิทธิผล ชั้นเคลือบนิกเกิลและทองคำด้วยไฟฟ้าบนชิ้นงานเหล็กกล้าไร้สนิม AISI 304 แผ่นบางตามขั้นตอนในอุตสาหกรรมซึ่งเป็นด้านเซลล์อัดประจุถูกตรวจสอบเฟสโดยใช้การเลี้ยวเบนของรังสีเอ็กซ์ และวัดขนาดความหนาเฉลี่ยด้วยภาพถ่ายอิเล็กตรอนแบบส่องกราด ด้านเซลล์ออกซิไดซ์ถูกเคลือบด้วยชั้นเคลือบนิกเกิล ผลการทดลองพบว่าที่อุณหภูมิ 301 K จากการคำนวณใช้เวลาการซึมผ่านและเวลาล่าช้า ค่าสัมประสิทธิ์การแพร่ไฮโดรเจนประสิทธิผลเฉลี่ยของเหล็กกล้าไร้สนิม AISI 304 ที่ไม่มีชั้นเคลือบด้านการอัดประจุ เหล็กกล้าไร้สนิม AISI 304 ที่มีชั้นเคลือบนิกเกิลด้วยไฟฟ้าด้านการอัดประจุ และเหล็กกล้าไร้สนิม AISI 304 ที่มีชั้นเคลือบทองคำด้วยไฟฟ้าด้านการอัดประจุ เท่ากับ 5.98x10-13, 6.05x10-13 และ 3.57x10-14 m2ꞏs-1 ตามลำดับ จากการคำนวณสัมประสิทธิ์การแพร่ไฮโดรเจนประสิทธิผลในเหล็กกล้าไร้สนิม AISI 304 ในชั้นเคลือบนิกเกิลและในชั้นเคลือบทองคำ มีค่าเท่ากับ 7.99x10-13, 3.40x10-14 และ 5.19x10-16 m2ꞏs-1 ตามลำดับ จากผลข้างต้น กล่าวได้ว่า ชั้นเคลือบทองคำด้วยไฟฟ้ามีประสิทธิภาพการต้านทานการแพร่ของไฮโดรเจนดีที่สุดเมื่อเปรียบเทียบกับเหล็กกล้าไร้สนิม AISI 304 และชั้นเคลือบนิกเกิลด้วยไฟฟ้า

การเตรียมพอลิอะคริเลตดัดแปรด้วยไซเลนโดยซีดอิมัลชันพอลิเมอไรเซชันเพื่อใช้ในงานเคลือบผิวสะท้อนน้ำ, วีพอล ประมวลกิจจา

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้ได้ทำการเตรียมพอลิอะคริเลตไซล็อกเซนอิมัลชันเพื่อนำมาใช้เป็นองค์ประกอบในสารเคลือบผิวสำหรับงานด้านการสะท้อนน้ำโดยเตรียมผ่านกระบวนการซีดอิมัลชัน และงานวิจัยนี้ได้นำไซโคลไซล็อกเซน (R-D4) ที่ได้จากกระบวนการรีไซเคิลซิลิโคนมาใช้เป็นสารตั้งต้นในการเตรียมพอลิอะคริเลตไซล็อกเซนอิมัลชันโดยใช้สารคู่ควบไซเลน (silane coupling agent) มาทำปฏิกิริยากับอะคริเลตมอนอเมอร์และไซโคลไซล็อกเซน โดยในงานวิจัยนี้ได้ศึกษาผลกระทบของการแปรเปลี่ยนอุณหภูมิ เวลา ชนิดของสารคู่ควบไซเลน 2 ชนิดได้แก่ ไวนิลไตรเอท็อกซีไซเลน (vinyltriethoxysilane, VTES) และ 2-(เมทาอริโลอิลโพรพิล) ไตรเมท็อกซีไซเลน (2-(trimethoxysilyl) propyl methacrylate, MPTMS) และปริมาณสารคู่ควบที่ใช้ในการทำปฏิกิริยา ต่อสมบัติทางกายภาพของพอลิอะคริเลตไซล็อกเซนอิมัลชันและฟิล์มแห้งของอิมัลชัน ผลที่ได้พบว่าพอลิอะคริเลตไซล็อกเซนอิมัลชันเตรียมได้โดยใช้สารคู่ควบไซเลนปริมาณร้อยละ 5-9 โดยน้ำหนัก ที่อุณหภูมิ 80 องศาเซลเซียสเป็นเวลา 7 ชั่วโมง ภายใต้บรรยากาศไนโตรเจน และฟิล์มแห้งของอิมัลชันที่ได้มีสมบัติความไม่ชอบน้ำเพิ่มขึ้นเมื่อมีปริมาณไซเลนเพิ่มขึ้น โดยพอลิอะคริเลตไซล็อกเซนอิมัลชันที่เตรียมด้วยสารคู่ควบ VTES ปริมาณร้อยละ 9 โดยน้ำหนัก ให้ฟิล์มที่มีความไม่ชอบน้ำมากกว่าพอลิอะคริเลตไซล็อกเซนอิมัลชันที่เตรียมด้วย MPTMS ในปริมาณที่เท่ากัน โดยสมบัติความไม่ชอบน้ำเป็นสมบัติสำคัญสมบัติหนึ่งของฟิล์มซึ่งวัดได้จากค่ามุมสัมผัสของหยดน้ำบนพื้นผิวฟิล์ม พบว่าฟิล์มจากพอลิอะคริเลตไซล็อกเซนอิมัลชันที่เตรียมด้วยสารคู่ควบ VTES ปริมาณร้อยละ 9 โดยน้ำหนัก มีค่ามุมสัมผัสน้ำเท่ากับ 104.65º ขณะที่ฟิล์มจากพอลิอะคริเลตไซล็อกเซนอิมัลชันที่เตรียมด้วยสารคู่ควบ MPTMS ในปริมาณเท่ากัน มีค่ามุมสัมผัสน้ำเท่ากับ 92.04º ดังนั้นจึงนำพอลิอะคริเลตไซล็อกเซนอิมัลชันที่ดัดแปรด้วยสารคู่ควบ VTES ร้อยละ 9 โดยน้ำหนัก ไปใช้เตรียมสารเคลือบผิวเชิงประกอบเพื่อช่วยเพิ่มสมบัติความไม่ชอบน้ำ และได้ศึกษาผลกระทบของการแปรเปลี่ยนอัตราส่วนโดยโมลของสารคู่ควบไซเลนต่อไซโคลไซล็อกเซนในการเตรียมพอลิอะคริเลตไซล็อกเซนอิมัลชัน ปริมาณและชนิดของฟูมซิลิกา ปริมาณและชนิดของออแกโนเคลย์ในสูตรสารเคลือบผิวเชิงประกอบ รวมถึงการศึกษารูปแบบของการเคลือบด้วยวิธีการจุ่มในการขึ้นรูปฟิล์ม จำนวนครั้งในการจุ่มเพื่อขึ้นรูปฟิล์มสารเคลือบ และชนิดของวัสดุพื้นผิวที่ถูกเคลือบต่อสมบัติทางกายภาพของฟิล์มสารเคลือบผิวเชิงประกอบ ผลที่ได้พบว่าสารเคลือบผิวเชิงประกอบที่ประกอบด้วยพอลิอะคริเลตไซล็อกเซนอิมัลชันที่ใช้อัตราส่วนโดยโมลของสารคู่ควบไซเลนต่อไซโคลไซล็เซนในการเตรียมเป็น 1:3 (PASVT9-13) และมีการใช้ออแกโนเคลย์ (NC20A) ปริมาณ 10 phr ร่วมกับ ฟูมซิลิกา (FSH15) ปริมาณ 35 phr เมื่อทำการเคลือบลงบนพื้นผิวแก้วและแผ่นไฟเบอร์ซีเมนต์ด้วยการจุ่มเป็นจำนวน 4 ครั้ง ทำให้พื้นผิวแก้วและแผ่นไฟเบอร์ซีเมนต์ที่ผ่านการเคลือบมีค่ามุมสัมผัสน้ำเท่ากับ 151.34 º และ 150.88 º ตามลำดับ ซึ่งแสดงถึงพื้นผิวมีความไม่ชอบน้ำแบบยวดยิ่งที่มีผลทำให้พื้นผิวเคลือบเกิดการสะท้อนน้ำได้ดี

Preparation And Photocatalytic Efficiency Of Graphitic Carbon Nitride/Silver-Titanium Dioxide Composite, Tanaporn Narkbuakaew

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aimed to synthesize high efficiency UV-visible light responsive g-C₃N₄/Ag-TiO₂ composite photocatalysts. The photocatalysts preparation method was classified into 3 parts. The first part was to study the influence of calcination temperature, %Ag loading content, and types of reducing agent on the photocatalytic performance of achieved Ag-TiO₂. The second part, effect of calcination temperatures and soaking time on preparation of high performance g- C₃N₄ photocatalysts under visible light irradiation were studied. Finally, the g- C₃N₄/Ag-TiO₂ composite was synthesized. Then, the photocatalytic performance of prepared photocalysts were investigated through cationic and anionic dye degradation under both UV and visible light …

Effects Of Electrodeposition Parameters On Zn-Tio2 Coating For Zinc-Ion Battery, Kittima Lolupiman

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research work has an aim to modify and develop to obtain environmentally friendly Zinc ion battery (ZIB) with low cost. Usually, the limit of Zn ion battery is occurred by dendrite growth during cycling of Zn anode leading to shorter service lifetime. Therefore, in this present work had an idea to modify electrodeposition process by adding TiO2 nano particles into coated Zn layers. This composite deposits were used as the anode materials of ZIBs. The only Zn and Zn/TiO2 composite coatings were deposited on the stainless-steel foil as modified anodes. The plating and stripping tests of symmetric cells reveal …

The Transcriptional Response Of Phanerochaete Chrysosporium And Trametes Versicolor To Growth On Stems Of Helianthus Argophyllus (Silverleaf Sunflower), Nadh Hamoud Alsubaie

Masters Theses

Traditional physicochemical and physicomechanical pretreatment technologies have improved the deconstruction of lignocellulose, but often require high energy inputs and added chemical reagents. Recent studies have demonstrated the use of white-rot fungi as alternative biological pretreatment agents that can mitigate these concerns. Although, white-rot fungi have been shown to grow on a variety of non-woody substrates, they have not been explored with respect to sunflower, which has the potential to provide raw materials for both biodiesel and bioethanol. In the present study, Silverleaf sunflower stems (Helianthus argophyllus) were used as substrates for the white-rot fungi Phanerochaete chrysosporium and Trametes …

Engineering Magnetic Properties Of Nanoparticles For Biomedical Applications And Magnetic Thin Film Composite Heterostructures For Device Applications., Shivakumar Hunagund

Theses and Dissertations

The motivation of this study is to investigate the size dependent properties of Gadolinium silicide nanoparticles and their potential applications in Biomedicine. We use two approaches in our investigation - size dependence and possible exchange interaction in a core-shell structure. Past results showed Gd₅Si₄ NPs exhibit significantly reduced echo time compared to superparamagnetic iron oxide nanoparticles (SPION) when measured in a 7 T magnetic resonance imaging (MRI) system. This indicates potential use of Gd₅Si₄ ferromagnetic nanoparticles as T2 contrast agents for MRI.

Until recently most contrast agents (CA) that are used in Magnetic Resonance …

Tools For Understanding Static Structure Factors And Their Application To Simulations Of Liquids, Travis Mackoy

Graduate Research Theses & Dissertations

Molecular dynamics (MD) simulations can be used to compute static structure factors (��(��)) and provide an interpretation of the underlying periodic atomic ordering. MD simulations complement experimentally measured ��(��) by allowing qualitative assignment of peaks to various ordering, such as cation-anion ordering in ionic liquids, via decomposition of ��(��) into partial ��(��). Here we present a method for classifying interatomic distances that allows for quantitative peak assignment and visualization of atoms that contribute most to each peak in calculated ��(��) for soft materials. The method is illustrated by investigating ��(��) for the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (C4C1pyrrTFSI), which shows two …

Characterization Of Boron/Iron-Oxide Core/Shell Structure For Boron Neutron Capture Therapy By Stem/Eels-Xeds And Mössbauer Spectroscopy, Mason Douglas Hayward

Graduate Research Theses & Dissertations

Boron/iron-oxide core/shell structured nanoparticles were characterized for application in boron neutron capture therapy (BNCT). BNCT is a cancer treatment method using the ability of boron to absorb thermal neutrons and a proposed drug delivery system utilizing an external magnetic field to direct the boron nanoparticles to targeted cancer sites and to extract the used nanoparticles after treatment. Boron nanoparticles were magnetically functionalized by encapsulating with an iron oxide shell. As such the exact composition, size distribution and oxidation states of the core/shell structures can affect treatment efficacy. Characterization was done by electron energy loss spectroscopy (EELS) and x-ray energy dispersive …

The Effect Of Curing And Zirconium Content On The Wettability And Structure Of A Silicate Hybrid Sol-Gel Material, Emma Machugh, Maikki Cullen, Alicja Kaworek, Brendan Duffy, Mohamed Oubaha

Articles

Functional hybrid sol-gel coatings have been developed for numerous applications with a wide range of wettabilities. This study proposes to investigate the relationship between the structure and the wetting properties of a zirconium modified silicate hybrid sol-gel coating. The structures of the coatings were altered by varying the content of zirconium, and the curing process, while keeping the sol-gel preparation conditions identical. The structure of the materials was characterized by FTIR, 29Si NMR and SEM. The thermal properties and the wettability are identified by DSC and contact angle measurements, respectively. By corroborating the structural and wettability analyses, it is shown …

An Investigation Of The Magneto-Active Slosh Control For Cylindrical Propellant Tanks Using Floating Membranes, Manikandan Vairamani, Pedro Llanos, Balaji Sivasubramanian, Somnath Nagendra, Kevin Crosby

Publications

The phenomenon of sloshing is a substantial challenge in propellant management, particularly in reduced gravity where surface tension-driven flows result in large slosh amplitudes and relatively long decay time scales. Propellant Management Devices (PMDs) such as the rigid baffles and elastomeric membranes are often employed to counteract motion of the free surface. In the present study, we investigate an active PMD that utilizes a free-floating membrane that, under an applied static magnetic field, becomes rigid and suppresses slosh. This semi-rigid structural layer can thereby replace bulky baffle structures and reduce the overall weight of the tank. In this paper, the …

Fundamental Insights On The Electrolysis Of Co2 Using Solid Oxide Electrolysis Cells, Juliana Silva Alves Carneiro

Wayne State University Dissertations

The work reported in this thesis focused on providing a fundamental understanding, at the molecular level, required to guide the effective design of electrocatalysts towards a superior reaction kinetics on the electrode of solid oxide electrolysis cells SOECs devices (SOECs) during the CO2 electrolysis. High temperature SOECs are electrochemical energy conversion technologies, that have emerged as promising alternatives to mitigate environmental issues associated with combustion-based technologies, such as the rising atmospheric CO2 levels. The conversion of excess CO2 into high-energy molecules, such as CO can be efficiently achieved through the use of SOEC – which facilitates the electrochemical reduction of …

Primary Dendrite Trunk Diameter In Al-7wt% Si Alloy Directionally Solidified Aboard The International Space Station, S. R. Upadhyay, Surendra N. Tewari, M. Ghodes, R. N. Grugel, D. R. Poirier, M. Lauer

Chemical & Biomedical Engineering Faculty Publications

Under a NASA (National Aeronautics and Space Agency)-ESA (European Space Agency) collaborative research project, MICAST (Microstructure formation in casting of technical alloys under a diffusive and magnetically controlled convection conditions), three Al-7wt% Si samples (MICAST-6, MICAST-7 and MICAST2-12) were directionally solidified at growth speeds varying from 10 to 50 µm s^-1 aboard the International Space Station to determine the effect of mitigating convection on the primary dendrite array. The observed primary dendrite trunk diameters during steady-state growth of MICAST samples show a good agreement with predictions from a coarsening based model developed by the authors. The trunk diameters in …

Design Of Embedded Wireless Sensors For Real-Time And In-Situ Strain Sensing Of Fiber Reinforced Composites, Relebohile George Qhobosheane, Sujjatul Islam, Muthu Ram Prabhu Elenchezhian, Vamsee Vadlamudi, Rassel Raihan, Kenneth Reifsnider

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

The increasing demand of early detection of barely visible damage inside fiber reinforced polymer (FRP) composites has led to the development of advanced microsensors capable of measuring local strains and defects within FRP composites. One of the major challenges in this type of local structural health monitoring (SHM) is the development of embedded sensors which can be safely placed into FRP composites while maintaining their high strength and light weight. This paper presents the development and investigation of a set of wireless magnetostrictive sensors embedded within the FRP composites for in-situ and real-time monitoring of local strains inside the composites. …

Synthesis Of Cadmium Arsenide Semiconductor Nanoparticles, Superatomic Silver Clusters, And Silver Coordination Polymers, Sarthak Jashubhai Patel

Legacy Theses & Dissertations (2009 - 2024)

Nanomaterials have chemical, electronic, optical, and other properties distinct from their bulk counterparts. However, the atom-precise synthesis of these materials remains a challenge, leaving open many scientific questions regarding the size regime between nanoparticulate (quantum confined) and bulk character. In this work, efforts toward the synthesis of nanoparticulate and atom-precise metal and semimetal materials are described. The synthesis of II-V semiconductor Cd3As2 having a near-zero bandgap is discussed. Analysis by UV-Vis absorption spectroscopy and powder X-ray diffraction indicate the formation of material with unexpected crystallinity and absorption properties The interaction between the molecular source of As and the solvent was …

Investigation Of Optical Second Harmonic Generation From Si (100) With Process Tailored Surface & Embedded Ag Nanostructures For Advanced Si Nonlinear Nanophotonics, Gourav Bhowmik

Legacy Theses & Dissertations (2009 - 2024)

The challenge of current microelectronic architecture in transmission bandwidth and power consumption can be potentially solved by using silicon photonics technologies that are compatible with modern CMOS fabrication. One of the critical active photonic devices for Si photonics is a Si based optical modulator. Most of the reported silicon modulators rely on the free carrier plasma dispersion effect. In those cases, a weak change of the refractive index obtained by carrier accumulation, injection or depletion is utilized in a Mach-Zehnder interferometer or a microring resonator to achieve intensity modulation, rendering them difficult for chip-level implementation due to a large footprint …

Cvd Molybdenum Disulfide : Material And Device Engineering, Eui Sang Song

Legacy Theses & Dissertations (2009 - 2024)

Molybdenum disulfide (MoS2) is a semiconducting 2D layered material that has attracted a lot of attention due to its material properties for electronics and optoelectronics device applications. These include a layer-dependent band gap, an indirect to direct energy transition at monolayer state, and strong light-matter interaction. A large majority of 2D materials and devices have been studied through micromechanical exfoliation for extraction and electron beam lithography for device fabrication. These methodologies while able to generate high quality materials and precisely fabricated devices, are not suitable for large scale production. Efforts have been made to make MoS2 and other 2D materials …

Low Energy Electron Interactions With Aliphatic And Aromatic Self-Assembled Monolayers On Au(111), Jodi Marie Grzeskowiak

Legacy Theses & Dissertations (2009 - 2024)

Understanding the interaction of low energy electrons with organic thin films is important for the development of many technological applications, one of which is extreme ultra-violet (EUV, 92 eV) lithography. At this energy, the photon will produce an electron cascade that induces most of the chemical changes within the photoresist. In order to better understand these interactions, electron scattering experiments have been performed on self-assembled monolayers (SAMs) of the aliphatic molecule 1-decanethiol and the aromatic molecule 1,1’-biphenyl-4-thiol grown on Au(111) via vapor phase deposition. The molecules take on either a lying down (LD) or standing up (SU) geometry depending on …

Synthesis And Adsorption Experiments With Metal-Organic Frameworks For High School And Undergraduate Laboratory Settings, Kate Holley

Legacy Theses & Dissertations (2009 - 2024)

Seven experiments are described and outlined here that introduce high school and undergraduate students to metal–organic frameworks (MOFs) and their applications. The experiments were designed to be completed with basic laboratory equipment and supplies and without the use of expensive characterization instruments, simulating typical high school chemistry laboratory conditions. Students synthesized two well-known MOFs, HKUST-1 and aluminum fumarate, using simple, safe, and rapid methods (fast enough to be performed within the time constrains of a typical high school class). Students then use their synthesized MOFs to explore their inherent sorption properties. In one set of experiments, the synthesized MOFs are …

Immune Modulation By Amphiphilic Oligonucleotides, Chunsong Yu

Wayne State University Dissertations

Immunotherapy is emerging as one of the most promising therapeutic strategies for cancer treatment in clinical practice. Immunotherapy leverages the host’s immune system to attack and kill tumor cells. Rationally-designed cancer vaccines are emerging as one of the powerful immunotherapies primarily because of the promise of inducing tumor antigen-specific immune responses. To improve immunogenicity of cancer vaccines, vaccine antigens are administered with vaccine adjuvants which can robustly activate innate immune system and subsequently lead to adaptive immune response. However, the major challenge of achieving significant therapeutic efficacy is lack of efficient targeted-delivery of vaccine components. By taking advantage of endogenous …

Novel Cathode Framework, Effective Electrolyte Modification, And Electrode Structural Modification Of High Performance Lithium Sulfur Batteries, Wenduo Zeng

Wayne State University Dissertations

Firstly, TiN nanotube arrays have been investigated as an effective skeleton in the cathode of lithium-sulfur batteries. A series of TiN nanotubes with various diameter and length have been synthesized and tested. Moreover, graphene nanoplatelets have been utilized as a structural anchor to support the TiN nanotubes, and the synergetic effect of composite material and its enhancement on Li-S battery electrochemical performance and cycling stability have been studied. Secondly, the improvement of electrode structural design has been evaluated for their effectiveness by using an in-situ characterization method with other electrochemical characterization. Lastly, the facile method of using transition metal cations …

Direct Laser Metal Deposition Of Nickel Based Superalloys, Abhishek Ramakrishnan-Sudha

Wayne State University Dissertations

Nickel-based superalloys are substantially used in the manufacturing of boilers for ultra-supercritical power plants and gas turbine hot-section as this grade of alloys provide higher yield strength with the rise in operating temperature and pressure owing to the presence of γʹ second phase precipitates. Conventionally, casting techniques such as centrifugal casting, investment casting, vacuum molding and several other casting based methods are used to fabricate the hot-section components. Nevertheless, a need for designing advanced materials with complex designs such as geometry, microstructure control, compositional changes, microstructure and property varying with the location as in functionally graded materials is not viable …

Inclusion Engineering In Femnal Steels, Rairu Vaz Penna

Masters Theses

"Low density high Mn and Al steels, or FeMnAl steels, show great promise for military vehicles and automotive applications in which high strength and toughness is a requirement. However, these steels are subject to processing challenges including development of oxide and nitride inclusions during melting and casting as well as a large as-cast grain size and heavy interdendritic segregation. This can lead to non-uniform heat treatment response and cracking during subsequent hot rolling. Adding up to 10%Al lowers the density of these steels by as much as 15%, unfortunately, this also results in large amounts of hard and faceted AlN …

Development Of Multicomponent Eam Potential For Ni-Based Superalloy, Muztoba Rabbani

Graduate Theses/Dissertations

We initiated the development of multi-component EAM potentials for Aluminides and Carbides, key phases in Ni-based Superalloys. The goal is to utilize the MD simulation to understand the deformation dynamics that contribute to the formation of voids and creep initiation. For this purpose, we constructed the raw data from ab-initio (molecular dynamics) MD simulations fed into the potential development code and used Nickel as the base metal with the addition of a number of various elements including Aluminum, Chromium, Tungsten. We then developed the EAM potentials for the aluminide and carbide phases using the force-fitting code MEAMfit. Our generated potential …

Characterization Of The Surface Condition In Aa6061 Resulting From Deep Rolling As A Function Of Common Industrial Parameters, Andrew Kenneth Layer

Masters Theses

"Roller burnishing is widely used in industry to improve the surface finish and fatigue life of components. As weight reduction continues to grow in the automotive and transportation industries, deep rolling can help maintain product performance by mitigating the increase in component stresses resulting from lower weight systems. Deep rolling parameters such as tool, applied angle, feed rate, spindle speeds, and relative tool direction all affect cycle time, product performance, and appearance. The effects of common industrial parameters on the resultant surface roughness and residual stress profiles were studied in this investigation. The samples were manufactured on a CNC lathe …

Epitaxial Growth Of Semiconductors And Chiral Metal Surfaces Using Spin Coating And Electrodeposition, Meagan V. Kelso

Doctoral Dissertations

"The current primary methods for epitaxial growth are energy intensive, requiring high temperature or high vacuum to obtain quality thin films. This dissertation explores the solution process methods of electrodeposition and spin coating for growth of epitaxial thin films. First, a method is developed to directly electrodeposit epitaxial CH₃NH₃PbI₃ perovskite for solar cells on single crystal Au by electrochemically reducing I₂ in organic solution. Perovskite is a newly explored material for solar cells, and its efficiency may be further improved by increasing the crystalline order. Second, a study on epitaxially electrodeposited chiral metal surfaces …

Oxide Inclusion Evolution And Factors That Influence Their Size And Morphology, Obinna M. Adaba

Doctoral Dissertations

"The evolution of oxide inclusion size distribution and the shape of the distribution during steelmaking and casting and the process variables that influence the inclusion characteristics at different stages were investigated and documented. A statistical method for transforming the 2D size distribution to their actual 3D distributions and the application of a kinetic model to determine nucleation and growth mechanisms were tested. Finally, laboratory experiments were performed to study the effects of preexisting inclusions, steel active oxygen content, and supersaturation on the size and morphology of Al₂O₃ inclusions.

The inclusion size, composition, and morphology following steel deoxidation …

Remanufacturing Of Precision Metal Components Using Additive Manufacturing Technology, Xinchang Zhang

Doctoral Dissertations

"Critical metallic components such as jet engine turbine blades and casting die/mold may be damaged after servicing for a period at harsh working environments such as elevated temperature and pressure, impact with foreign objects, wear, corrosion, and fatigue. Additive manufacturing has a promising application for the refurbishment of such high-costly parts by depositing materials at the damaged zone to restore the nominal geometry. However, several issues such as pre-processing of worn parts to assure the repairability, reconstructing the repair volume to generate a repair tool path for material deposition, and inspection of repaired parts are challenging. The current research aims …

Utilizing Of Magnesium Oxysulfate Binders For Additive Construction Applications, Hatem Hashem Al-Masaeid

Electronic Theses and Dissertations

This dissertation is serving multiple transdisciplinary top-notch material design and technological topics. It is a proof of concept of the feasibility of 3D printing using Magnesium Oxysulfate (MOS) binder as an alternative to the ordinary Portland cement (OPC) to be utilized in terrestrial and extraterrestrial additive construction (AC) fields. MOS paste and mortar are characterized physically, chemically, and mechanically. The characterization results conducted in this research show how MOS’s properties can be controlled to match the 3D printing requirements by manipulating the MOS’s ingredients proportions.

Characterization Of Nanostructure, Materials, And Electron Emission Performance Of Next-Generation Thermionic Scandate Cathodes, Xiaotao Liu

Theses and Dissertations--Chemical and Materials Engineering

Scandate cathodes, where scandia is added to the tungsten cathode pellets, have recently received substantial and renewed research interest owing to significantly improved electron emission capabilities at lower temperatures, as compared with conventional dispenser cathodes. However, there are several persistent issues including non-uniform electron emission, lack of understanding regarding scandium’s role in the emission mechanism, and unreliable reproducibility in terms of scandate cathode fabrication. As a result, scandate cathodes have not yet been widely implemented in actual vacuum electron devices (VEDs).

The surface structure and chemical composition of multiple scandate cathodes – prepared with the powder using the liquid-solid (L-S) …

Investigation Of Transition-Metal Ions In The Nickel-Rich Layered Positive Electrode Materials For Lithium-Ion Batteries, Shuang Gao

Theses and Dissertations--Chemical and Materials Engineering

Layered lithium transition-metal oxides (LMOs) are used as the positive electrode material in rechargeable lithium-ion batteries. Because transition metals undergo redox reactions when lithium ions intercalate in and disintercalate from the lattice, the selection and composition of transition metals largely influence the electrochemical performance of LMOs. Recently, a Ni-rich compound, LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811), has drawn much attention. It is expected to replace its state-of-the-art cousins, LiCoO₂ (LCO) and LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111), because of its higher capacity, lower cost, and reduced toxicity. However, the excess Ni, as a …