Metallurgy Commons^™

Microwave-Assisted Reduction Of Critical Metal Oxides From E-Waste Mixture, Kurundu Shavinka Jayasekera

Graduate Theses, Dissertations, and Problem Reports (ETD)

The efficient recovery of critical metals such as tantalum (Ta), manganese (Mn), gallium (Ga), and indium (In) from electronic waste (e-waste) is essential for resource sustainability and environmental protection. This research uses microwave-assisted treatment to investigate the carbothermal reduction of these four specific metals from their oxides in a simulated e-waste mixture, with carbon black serving as both a microwave coupling and reduction agent. Microwave processing is used specifically because it offers a rapid and energy-efficient alternative to conventional thermal methods, with the benefits of intrinsic heating and selective heating of materials. The first experiments centered on understanding the effects …

Fabrication And Characterization Of Cast Copper Heatsinks For Computer Chip Cooling, John James Recktenwald

Graduate Theses, Dissertations, and Problem Reports (ETD)

Humanity has worked copper for millennia, from primitive tools in prehistory to the wires and cooling solutions facilitating the modern digital age. While high performance fin style heatsinks are commonplace, more complex heatsink geometries in high performance applications are rare due to manufacturing challenges. In this study a casting process was developed to fabricate copper pin fin heatsinks. To assess the performance of heatsinks fabricated using the process three pin fin heatsinks were fabricated, one machined from a commercially manufactured billet, one machined from a cast block, and one cast directly to final shape. Each of the three heatsinks were …

Inherently Porous Metal Structures With Sufficient Mechanical Properties Through Direct Writing Of Bio-Based Inks, Havva Eda Aysal

Graduate Theses, Dissertations, and Problem Reports (ETD)

There is currently a burgeoning interest in developing 3D printed metal structures with inherent porosity and sufficient mechanical properties for mass customization in the biomedical field. Current approaches for 3D printing of biocompatible metals rely on powder-bed fusion methods which are energy intensive and utilize large amounts of metal powder that is challenging to recycle. In addition, such methods aim on producing dense parts and porosity generation, within the printed part, is challenging due to the complex physics of the melting pool. Here, a relatively new and promising approach is undertaken to study the 3D printing of inherently porous structures …

Investigation Of Oxidation And Corrosion Resistance Of Ni-Based Alloys And Stainless Steels Under Co2 Environments At Elevated Temperatures, Spencer Roy Fultineer

Graduate Theses, Dissertations, and Problem Reports (ETD)

High mechanical strength integrity, high robustness towards oxidation, and high resistance to carburization under CO2 environments at elevated temperatures are usually required for metallic systems that are employed for power generation. INCONEL 625 is a nickel-based superalloy that started development in the 1950s. This material was designed with the distinct purpose of use in high-temperature and high-pressure systems. While various materials possess the physical properties to handle these conditions, the creation of IN625 addresses the need for a material to withstand the highly corrosive properties of these kinds of environments. In order to evaluate the oxidation and corrosion resistance of …

Minimizing Cr-Evaporation From Balance Of Plant Components By Utilizing Cost-Effective Alumina-Forming Austenitic Steels, Lingfeng Zhou

Graduate Theses, Dissertations, and Problem Reports (ETD)

A solid oxide fuel cell (SOFC) is a clean and efficient energy conversion device. The development of intermediate-temperature SOFCs has made it preferable to use metallic interconnects (MICs) to greatly reduce the cost and significantly increase the efficiency compared to ceramic interconnect materials. However, gaseous chromium species will evaporate from the chromium-containing layer formed on the surface of commonly used MICs and balance of plant (BoP) components. Volatile chromium species have been shown to form solid deposits which poison the cathodes of SOFCs, causing drastic cell performance degradation and thereby limiting commercialization. In order to alleviate the Cr poisoning and …

Functionally Magnetic Gradient Copper-Nickel Material Fabricated Via Directed Energy Deposition, Vy Tran Phuong Nguyen

Graduate Theses, Dissertations, and Problem Reports (ETD)

Functionally gradient materials (FGMs) of CuSn10 and Inconel 718 were fabricated via a hybrid directed energy deposition (DED) system. The objective of the present thesis is to determine the feasibility of manufacturing CuSn10 and Inconel 718 FGMs via DED and investigate the physical and mechanical properties and the microstructures of the resulting FGMs. The physical tests comprised of conductivity and Seebeck coefficient measurements. The microstructure analysis and mechanical testing include microscopic imaging, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and hardness test. In addition, compressive strength test was performed to analyze the interface bonding behaviors.

Development Of Oxide Dispersion Strengthening (Ods) Alloys Powder For Additive Manufacturing, Changyu Ma

Graduate Theses, Dissertations, and Problem Reports (ETD)

Additive manufacturing (AM) fabricated oxide dispersion strengthened (ODS) alloys are given high expectations for critical structural components such as the first stage turbine blade for their excellent creep strength and oxidation resistance compared to superalloys. However, the powder feedstock processing is still an open question since current state-of-the-art processes are not capable of achieving ultrafine strengthening elements such as Y₂O₃ in powder which leads to agglomeration issues in as-consolidated alloys. In this research, the oxidation behavior and stability of ultrafine oxide in AM-printed alloys using mechanically alloyed powders were evaluated at 1100 ^oC. In addition, a …

Calcite Depression In Bastnaesite-Calcite Flotation System Using Organic Acids, Emmy Muhoza

Graduate Theses, Dissertations, and Problem Reports (ETD)

Bastnaesite is the primary source of light REEs, namely cerium (Ce), lanthanum (La), praseodymium (Pr), neodymium (Nd), to name a few. Bastnaesite is typically concentrated using the froth flotation beneficiation method. Flotation of bastnaesite suffers from high reagent consumption due to the similar surface characteristics of bastnaesite and associated gangue minerals, including calcite. Additionally, complex stages of high-temperature conditioning are often required to suppress the detrimental impact of dissolved calcium ions on the flotation of bastnaesite. This research seeks to investigate the capabilities of organic acids in the bastnaesite-calcite flotation systems to selectively depress calcite minerals and effectively chelate calcium …

Recovery Of Phosphorus From Florida Phosphatic Waste Clay, Amir Eskanlou

Graduate Theses, Dissertations, and Problem Reports (ETD)

This MS thesis examines the recovery of phosphorus (P) from Florida waste clay (WC). A comprehensive literature review revealed that: (i)-The most important values being lost to WC are P and rare earth elements (REEs). For the recovery of these values from WC, two crucial attempts are the removal of extremely fine-sized clays, followed by the recovery of phosphate content, which can pave the path for the recovery of REEs; (ii)-Any scientific/ technological solution should, at the same time, be economically and environmentally attractive to the industry. As such, moving from mostly chemical separation processes to the primarily physical/ physicochemical …

Recovery Of Rare Earth Elements (Rees) From Coal Mine Drainage Sludge Leachate, Panpan Ren

Graduate Theses, Dissertations, and Problem Reports (ETD)

Acid mine drainage (AMD) is the primary cause of aquatic habitat loss in the Appalachian Coal Basin and many other mining districts across the U.S. and the world. The objective of this work is to develop a cost-effective and environmentally benign process to treat and recover Rare Earth Elements (REEs) from AMD. Solvent extraction (SX) is one effective way to turn AMD into a commercially viable feedstock for rare earth production.

In this work, SX experiments were conducted on Y-Ca-Mg-Al-HDEHP-n-heptane-HNO3-H2O system to simulate AMD treatment for Yttrium recovery by changing four parameters: pH values, concentration ratio of Yttrium (Y) over …

Development Of Oxide-Dispersion-Strengthened Nickel-Based Super Alloy Powders For Additive Manufacturing, Sizhe Huang

Graduate Theses, Dissertations, and Problem Reports (ETD)

Oxide-Dispersion-Strengthened (ODS) Nickel-Based superalloy has been drawn a huge attention and developed with good oxidation resistance, corrosion resistance and high creep strength. It has been considered as critical materials for Additive Manufacturing (AM). The quality and the efficiency of fabrication methods of ODS limits the performance of itself on AM. The development of new type of ODS, new methodologies and evaluation techniques are required if the enhanced quality of ODS and enhanced efficiency of fabrication are to be achieved. Of the current fabrication techniques for AM, Gas Atomization (GA) is widely used since they can generate spherical powders with high …