Metallurgy Commons^™

Application Of 3d Printing Technology In Porous Anode Fabrication For Enhanced Power Output Of Microbial Fuel Cells, Bin Bian

Electronic Thesis and Dissertation Repository

Microbial fuel cells (MFCs) are widely researched for application in wastewater treatment. However, the current anodes used in MFCs often suffer from high fabrication cost and uncontrollable pore sizes. In this thesis, three-dimensional printing technique was utilized to fabricate anodes with different micro pore sizes for MFCs. Copper coating and carbonization were applied to the printed polymer anodes to increase the conductivity and specific surface area. Voltages of MFCs with various anodes were measured as well as other electrochemical tests such as linear sweep voltammetry and electrochemical impedance spectroscopy. 3D copper porous anode produced higher maximum voltages and power densities …

Environmental Degradation Of Nickel-Based Superalloys Due To Gypsiferous Desert Dusts, Matthew B. Krisak

Theses and Dissertations

More than twenty-five years of continuous operation in the dusty environments of Southwest Asia have shown that degradation of gas turbine engine components due to particle ingestion is a serious threat to operations. In particular, the continued push for higher engine operating temperatures has brought a new emphasis to the damage mechanisms (for example CMAS glass formation and hot corrosion) caused by ingested particles forming molten deposits on engine components. Despite decades of research little progress has been made to mitigate the effects of CMAS and hot corrosion degradation to engine components. This research focused on hot corrosion specifically. A …

Incipient Plasticity Of Metals And Alloys Using Nano-Indentation Technique, Dong Wu

Doctoral Dissertations

The incipient plasticity indicates the nucleation or activation of defects in materials and enables us to study the intrinsic mechanical properties of materials. In this dissertation, instrumented indentation technique was employed to study the incipient plasticity of metals (bcc-Cr, fcc-Ni, fcc-Au) and a fcc-structured high entropy alloy (HEA) NiFeCoMnCr. The critical shear stresses for pop-in in these materials were all within the range of theoretical strength of materials, indicating the nucleation of dislocations in perfect crystals.

In Chapter 3 and 4, indentation tests were conducted at elevated temperatures to study the pop-in behavior in bcc-Cr and fcc-Au. The pop-in load …

An Investigation Of Incipient Melting During Solution Heat Treatment Of 7050 Aluminum Forgings And Its Effect On Corrosion Properties, Thomas Kilkenny

Materials Engineering

7050 alloy (6.2Zn-2.3Mg-2.3Cu-0.12Zr) is a structural aluminum alloy commonly used in the aerospace industry. Its rich chemistry makes it susceptible to incipient melting. Incipient melting is a phenomenon where areas with high local alloy content melt before the rest of the material. This can cause a degradation of mechanical and corrosion properties. A six by four factor solution heat treatment trial was conducted. Six solution heat treatment temperatures, 890- 940°F in 10°F increments, and four times, 1, 2, 4, and 6 hours, were used. Incipient melting was observed in the 910°F, 6 hour solution heat treatment and all 920-940°F solution …

Effect Of Time Delay Between Etching And Adhesive Bonding (“Outlife” Time) On Lap-Shear Strength Of Aluminum Alloys Using Environmentally-Friendly P2 Etch, Josh Barkhimer, Matthew Erich, Gokul Nair

Materials Engineering

Raytheon Company currently uses a Forest Products Laboratory (FPL) paste etchant for preparing aluminum surfaces for adhesive bonding, and FPL is a source of hazardous hexavalent chromium. The goal of this study was to evaluate a less-toxic P2 paste etchant as a possible replacement. Coupons of 2024-T3, 6061-T6, and 7075-T6 grades of aluminum alloy were solvent-degreased, abrasively cleaned, and etched at room temperature using P2 paste following a strict protocol adopted from Raytheon. Coupons were then left exposed to air for assigned time intervals (or “outlife” times) of 0, 1, 4, 8, 16, and 63 or 72 hours. The aluminum …

Effects Of Initial Forging Temperature, Cooling Rates, And Carbon Content On Primary Alpha Formation In Ti-6al-4v, James Tillman, Hui Wei

Materials Engineering

Ti-6Al-4V is an alpha-beta titanium alloy system, which contains both alpha and beta phases at room temperature. Both alpha and beta phases provide Ti-6Al-4V a range of different properties for a range of applications. In order to improve the energy efficiency and better satisfy customers’ requirements of less than 52% primary alpha phase, Weber Metals sponsored this project to study the effects of carbon content, forging temperature, and cooling rates on primary alpha formation in Ti-6Al-4V alloys. There has been a lot of discussion as to whether or not carbon, a known alpha stabilizer, will affect the microstructure in small …

Effects Of Composition And Solid Solution Strengthening On The Compression Strength Of Iron-Based Hardfacing Alloys, Tyler Wiggins, Samuel Garrison-Terry

Materials Engineering

Three iron-based hardfacing alloys were fabricated to have a tungsten strengthened matrix with varying compositions of 10-15, 20, and 30 wt% tungsten/chrome boride content. The fourth sample was fabricated to have a molybdenum solid solution strengthened matrix with 10-15 wt% W/Cr Boride content. This project focuses on the compressive strength of iron-based hardfacing alloys. Preliminary compression tests with Scoperta iron-based hardfacing alloys showed a need for sample dimension reduction due to compressive loads that could not be met by a 50 kN maximum capacity mechanical testing system. The preliminary tests showed compressive strengths exceeding 2340 MPa. Samples of the current …

Investigating The Cause Of Unique Mechanical Behavior In Platinum Alloy Guidewire Tips, Evan Borgeson, Alfred Rosen

Materials Engineering

The platinum alloy used by Abbott Vascular in guidewire tips exhibits a yielding behavior characterized by an abrupt transition from elastic to plastic zones and high ductility. This yielding behavior was hypothesized to be a result of one of three structural phenomena: ordering, solute strain aging, or interstitial strain aging. To test for these strengthening mechanisms in the wire, X-ray diffraction analysis, heat treatments, and tensile testing were completed. The wire has a diameter of 0.0025 inches and was supplied in two forms, the final stress relieved state, and as-drawn from the production line. Heat treatments were performed at 130 …

Electrochemical Testing Of Aluminum-Lithium Alloys 2050, 2195, And The Current Aerospace Industry Standard 7075 To Measure The Galvanic Corrosion Behavior With Ti-6al-4v, Trent Duncan, Kevin Knight

Materials Engineering

This project aimed to characterize the electrochemical behavior of four different aluminum alloys, and determine how much galvanic corrosion would occur when each alloy was coupled to Ti-6Al-4V. The particular alloys tested were 2050-T3, 2050-T852, 2195-T852, and 7075-T7352. These alloys were tested to determine the effects of aging, and adding lithium, to the corrosion behavior of aluminum alloys. Potentiodynamic polarization curves were generated using the Parstat 2273 potentiostat in accordance with ASTM standard G5, and corrosion analysis software was used to produce Tafel fit lines, which determined the open circuit potential (E_corr) of each sample. Nine tests were …

Characterization Of Laser Deposited Ti-6al-4v To Nb Gradient Alloys, Clincy Cheung

Materials Engineering

An alloy was fabricated with Ti-6Al-4V and Nb powder using laser deposition (LD) to form a compositional gradient. The gradient was deposited, starting with Ti-6Al-4V powder, onto a forged Ti-6Al-4V substrate in an Argon environment. Niobium (Nb) composition increased by 4-at.% with each layer deposited until the composition reached 100-at.% Nb. This process yielded steep thermal gradients and affected the microstructure and mechanical properties across the compositional gradient. To observe the microstructural changes in the alloy, an etched gradient was viewed with optical microscopy at 1000x, where the grain structure was observed to be an acicular α phase at 100-at.% …

Analysis Of Shear Strength Variance Of Ph 15-7 Mo Blind Rivet Stems For Aerospace Applications, Miles Macarthur, Kent C. Majewski

Materials Engineering

This project attempts to reduce manufacturing costs incurred to Cherry Aerospace by variance in material properties. To track and predict the shear strength of PH 15-7 Mo stainless steel rivet stems throughout the heat treatment process, samples were taken from several steps in the manufacturing process and experimental heat treatments were performed across a range of temperatures. The supplied rivet stems were heat treated for four hours at temperatures from 520°C to 560°C, in increments of 10°C. Double shear testing in accordance with ASTM 1312-13A revealed that there is no apparent correlation between the strength of the supplied wire and …

The Design Of An Optimized Patient-Specific In Vivo Spinal Fusion Cage Using Additive Manufacturing, Gorman Donnelly

Honors Theses

This project involved the design of an all-in-one patient-specific lumbar spinal fusion cage using Direct Metal Laser Sintering (DMLS) manufacturing. The cage is zero-profile and does not need the use of supplemental fixation. It was manufactured out of the titanium alloy Ti 6Al-4V using a DMLS rapid prototyping machine from a third party company. The endplates of the cage are patient-specific allowing for a larger surface contact area between the cage and the vertebral bodies than most cages on the market. This fosters a more successful fusion as well as decreases surgery time, effectively decreasing recovery time. Different porosity variations …

Engineering The “Pluripotency” Of Zr-Based Bulk Metallic Glasses As Biomedical Materials, Lu Huang

Doctoral Dissertations

Bulk metallic glasses (BMGs) are a family of novel alloys with amorphous microstructures. The combination of their excellent mechanical properties, good chemical stability, high thermal formability, and general biocompatibility has brought up new opportunities for biomaterials. Research in this dissertation was focused on exploring multiple biomedical functionalities of Zr-based BMGs over a wide spectrum, combining materials and biological characterizations, through experimental and computational approaches. Four distinct yet interconnected tasks were endeavored, involving inflammation, hard-tissue implant, soft-tissue prosthesis, and pathogenic infection.

The inflammation that can be potentially triggered by Zr-based BMGs was investigated using macrophages. Lower level or comparable macrophage activations …

Microstructures And Mechanical Behavior Of Nial-Strengthened Ferritic Alloys At Room And Elevated Temperatures, Zhiqian Sun

Doctoral Dissertations

In order to improve the thermal efficiency and decrease the greenhouse gases emission, it is required to increase the steam temperature and pressure in fossil-energy power plants. In the United States, research has been performing in order to push steam temperature to 760 Celsius degree and steam pressure to 35 MPa. However, the highest operational temperature for current commercial heat-resistant ferritic steels is ~ 620 Celsius degree. In this sense, new advanced ferritic alloys with better creep resistance are needed, considering such service conditions in next-generation ultra-supercritical fossil-energy power plants.

Coherent B2-ordered NiAl-type precipitates have been employed to reinforce the …

Molecular Dynamics Simulation Of Irradiation Damage In Multicomponent Alloys, Wei Guo

Doctoral Dissertations

The development of the generation IV reactors calls for radiation resistant materials. This thesis proposes that the newly developed single phase solid solution of high-entropy alloys (HEAs) can be such candidates. HEAs can undergo the crystalline to amorphous to crystalline (C-A-C) transitions under radiation. The radiation induced amorphous structure is a highly radiation resistant medium as shown by previous studies, and it further transforms to crystalline phases without much structural defects. In this thesis, by reviewing the formation rules of solid solutions and amorphous metallic glasses, it is suggested that the atomic size plays a key role affecting the C-A-C …

Resonant Spectra Of Metal Nanotoroids Of Various Sizes, Huong Quynh Tran

Electrical Engineering Undergraduate Honors Theses

Nowadays, the manipulation of light by using metallic nanostructures has wide applications in photonics, optoelectronics and energy conversion. Along with other universities all over the world, the University of Arkansas is researching on nano-antennas’ design, fabrication and applications. Current research in Dr. El-Shenawee’s Terahertz Imaging and Spectroscopy Computational Electromagnetics Group, has computationally investigated the behaviors of plasmonic nanostructures by using the commercial finite element electromagnetic solver Ansys® HFSS. This work reproduced the previous work of spectral absorption enhancement of infinite and finite arrays of silver and gold nanotoroids with sizes of the inner radii: 13nm – 21nm, while outer radius …

Studies Of High Temperature Hydrogen Related Damage In Welded Carbon Steel Components Used In Refineries, Maneel Bharadwaj

Masters Theses

Five materials encompassing various grades of carbon steel were received from retired and ex-service petroleum refinery equipment for root-cause evaluation of High Temperature Hydrogen Attack (HTHA) damage at UTK. These materials were submitted by three contributors: Irving Oil Refinery (IOR #1110-2), Valero (#67 & #1252134), and Phillips 66 (#555-S1 & #555-S2) on behalf of American Petroleum Institute (API). These materials originated from various flange-to-pipe welded components that were exposed in hydrogen pressure environment at elevated temperatures (> 640°F and >70 psia).

A singular crack originating at the flange inside surface just outside of the visible HAZ was observed in IOR …

Estimation And Thermodynamic Modeling Of Solid Iron Species In The Berkeley Pit Water, Rajesh Srivastava

Graduate Theses & Non-Theses

Since the cessation of open-pit mining activities from the Berkeley Pit located in Butte, MT in 1982, the pit had gradually filled with metal-laden acidic mine water. The purpose of this investigation was to estimate and apply thermodynamic theory to a group of iron-sulfate solids that might equilibrate with the Berkeley Pit water. Thermodynamic data was incomplete for acid mine affected water, and the effects of Cu cementation on the formation of iron oxide and sulfate solids had not been analyzed. Ferric iron compounds such as Ferrihydrite, Goethite, Schwertmannite, Potassium Jarosite and Potassium Hydronium Jarosite were modelled in Stabcal using …

Voltammetric Investigation Of Xanthate Chemisorption On A Chalcopyrite Surface, Jesse Lynn Bowden

Graduate Theses & Non-Theses

Cyclic Voltammetry experiments have been conducted on copper, iron, and chalcopyrite (CuFeS2) and compared to mass-balanced EH-pH Diagrams. Potassium ethyl xanthate (KEX) was added to solution and additional voltammetry experiments were performed to determine the surface chemistry reactions of flotation collector in solution with these minerals. The ultimate goal of this research was to investigate the possibility of xanthate chemisorption onto the chalcopyrite mineral surface. Results of the copper mineral testing confirm previous literature studies and corroborate published isotherm data. Results of the iron mineral testing showed changes in surface reactions with the addition of potassium ethyl xanthate to solution, …

Thermodynamic Considerations In Molten Salt Electrolysis For Rare Earth Metals, Arwin Gunawan

Graduate Theses & Non-Theses

Many applications utilize rare earths as a part of their essential composition, such as: Ni-MH batteries, glass screen, magnets, fluorescent lightning, etc. These reactive elements are normally found as an oxide compound due to their affinity with oxygen. Their oxide formation exhibits a high standard free energy, which make them really stable. Consequently, extracting rare earths cannot be easily done with a simple acid-base reaction.

It has been known that there are two reduction ways to extract rare earth, metallothermic reduction and molten salt electrolysis process. Metallothermic method is determined by standard free energy formation, melting point, boiling point, vapor …

Thermal Processing And Mechanical Properties Of Beta Phase Titanium Alloys For Biomedical Applications, Ethan Wood

Graduate Theses & Non-Theses

The past few decades have seen an increase in the use of beta titanium alloys as structural biomaterials. Their combination of excellent mechanical properties, corrosion resistance and biocompatibility, along with a lower Young’s modulus than stainless steel, cobalt-chromium and commercially pure titanium make the beta titanium alloys ideal biomaterials. This work evaluates the use of three beta titanium alloys for biomedical applications. Three beta titanium alloys, Ti 15-3-3-3, Ti SP-700 and Ti Beta-C, underwent thermal processing to optimize mechanical properties. The alloys were subjected to tensile testing, hardness testing, fatigue testing, optical microscopy and SEM fracture analysis in order to …

Optimization Of Rare Earth Leaching From Ores And Concentrates, Grant Wallace

Graduate Theses & Non-Theses

The use of applied chemistry in the production and optimization of leach solutions from Rare Earth Element (REE) ores and concentrates was investigated. Ore and concentrate samples were characterized using scanning electron microscopy/mineral liberation analysis (SEM/MLA), X-ray Diffraction (XRD), and Inductively-coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Multiple leach tests were performed to analyze the effects of temperature, residence time, and reagent concentration on the leaching of REEs. Analysis of leach solutions was carried out using ICP-AES. Modeling and statistical analysis of extraction behavior was carried out using DesignExpert 9. Modeling data for multiple REEs indicate that extraction is strongly influenced …

Nanomechanical And Scaling Behavior Of Nanoporous Gold, Nicolas J. Briot

Theses and Dissertations--Chemical and Materials Engineering

Nanoporous metals have recently been drawn significant interest in various fields of research. Their high surface-to-volume ratio present a strong potential for applications in sensing, catalysis, micro-electromechanical systems (MEMS) and even in the medical field. However, the mechanical properties of nanoporous metals have not yet been well determined, as conducting mechanical tests was found to be challenging. Scaling relations linking the mechanical properties of porous materials to those of their dense counterparts are successfully and widely used for many porous metals. However, their applicability to nanoporous metals have recently been questioned, as estimations from the classic scaling relations were found …

Sustainable Disposal Of Coal Processing Waste Streams, Mohammad Rezaee

Theses and Dissertations--Mining Engineering

Modern coal preparation facilities incorporate a wide array of solid-solid and solid-liquid separation processes for rejecting mineral matter to meet market specifications. The coarse mineral matter is typically placed into engineered refuse piles whereas the fine refuse is either stored in impoundments or co-disposed with the coarse refuse. The discharge water from the refuse material represents an environmental concern due to the potential release of trace elements, and the subsequent elevation of total dissolved solids and conductivity. The research findings reported in this dissertation addresses sustainable coal processing waste disposal through using strategies aimed at minimizing the environmental impacts. To …

The Examination Of Stress Corrosion Cracking In High Strength Carbon Steel Through Combined Mechanical-Electrochemical Testing, Jacob Sines

Williams Honors College, Honors Research Projects

Through the analysis of materials and environments seen in industry a better understanding of the fundamentals behind degradation mechanisms can be observed. The scope of this project was to better understand the fundamentals behind the degradation of high strength pipeline steels in a lab setting to simulate an environment seen in industry. Specifically the degradation mechanisms of high and nearly neutral pH stress corrosion cracking were examined in environments that simulated oil and gas pipelines buried in soil. Experimentation was carried out utilizing X65 carbon steel specimen, a Gamry potentiostat, a CORTEST proof ring, a CORTEST slow strain rate machine, …

Containment Materials For Thin-Strip Casting Of Steel, Abhishek Kumar

Doctoral Dissertations

"The focus of this research was to investigate the corrosion behavior of BN-based and ZrO₂-C refractories by molten steel. These refractories are used as side-dam and core-nozzle in the thin-strip casting of steel. The improvement and development of these refractory components will increase the process efficiency by prolonging the refractory service life.

The first part of this study focused on interaction of BN-ZrO₂-SiC side-dams with steel-inclusion system in a laboratory setup under argon gas environment. It was observed that corrosion of this ceramic was severe in contact with steel compared to slag/inclusion.

The second part of …

Engineered Surface Properties Of Porous Tungsten From Cryogenic Machining, Julius M. Schoop

Theses and Dissertations--Chemical and Materials Engineering

Porous tungsten is used to manufacture dispenser cathodes due to it refractory properties. Surface porosity is critical to functional performance of dispenser cathodes because it allows for an impregnated ceramic compound to migrate to the emitting surface, lowering its work function. Likewise, surface roughness is important because it is necessary to ensure uniform wetting of the molten impregnate during high temperature service. Current industry practice to achieve surface roughness and surface porosity requirements involves the use of a plastic infiltrant during machining. After machining, the infiltrant is baked and the cathode pellet is impregnated. In this context, cryogenic machining is …

Factors Affecting The Heat Transfer During The Dip Testing Of Potential Third Generation Advanced High Strength Steels, Kramer Michael Pursell

Masters Theses

"A dip tester was designed and built at Missouri University of Science and Technology to test the effects of the primary alloying elements (Mn, Si, and Al) of Fe-Mn-Al-Si-C type 3rd generation advanced high strength steel (AHSS) alloys, dipping superheat, and dipping speed on the heat transfer during rapid solidification. The difficulties associated with casting 3rd generation AHSS were compiled as well to serve as a best-practices guide. An extensive list of potential 3rd generation AHSS alloys was developed and tested, and the effects of various dip testing parameters were examined.

Manganese was found to increase the heat flux by …

Understanding Impurities In Copper Electrometallurgy, Paul Laforest

Masters Theses

"This work involves examining two industrial reports of methods to handle impurities in copper electrowinning and electrorefining. The first part evaluates the addition of Hydrostar, Cyquest N-900, DXG-F7, and Guartec EW to copper electrowinning electrolyte to affect MnO₂ deposition on coated titanium anodes (CTAs). The second part examines the effects of anode chemistry and thiourea addition on the ductility of electrorefined copper starter sheet.

In part one, a laboratory cell was used to simulate a short cycle electrowinning cell via chronopotentiometric operation with an IrO₂-Ta₂O₅ CTA at 40⁰C. A cyclic voltammetric sweep was applied …

Preliminary Investigation Into The Cause Of Pinhole Porosity In Aluminum Metal Castings From Serpentine Impurities In Olivine Sand, Brodie J. Biersner

Dissertations and Theses @ UNI

The problem addressed in this study is how contaminates in the foundry molding aggregate olivine, affect aluminum castings during the casting process. This research will concentrate on hydrated contaminates, specifically the mineral serpentine. The purpose of this research is to better understand how hydrated minerals contribute to the generation of pinhole porosity defects during the casting process. Understanding how impurities in foundry aggregates affect the casting process would aid in the reduction of scrap caused by core and molding sands, ultimately providing savings to the casting manufacturer.

A foundry grade olivine was compared to a new source of olivine to …