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Full-Text Articles in Engineering

A Computational Investigation Of The Interstitial Oxidation Thermodynamics Of A Mo-Nb-Ta-W High Entropy Alloy Beyond The Dilute Regime, Adib J. Samin Dec 2020

A Computational Investigation Of The Interstitial Oxidation Thermodynamics Of A Mo-Nb-Ta-W High Entropy Alloy Beyond The Dilute Regime, Adib J. Samin

Faculty Publications

High entropy alloys (HEAs) are promising candidates for high-temperature structural material applications. Oxidation is a major factor that must be accounted for when designing such materials and it is thus important to study the oxidation behavior of HEAs to enable the optimum design of next generation materials. In this study, the thermodynamic behavior of interstitial oxygen in a Mo-Nb-Ta-W high entropy alloy was explored beyond the dilute limit. This was accomplished by sampling configurations of the HEA and HEA-oxygen systems from an isothermal–isobaric ensemble using a series of first-principle-based Monte Carlo simulations. It was found that the interstitial oxygen had …


Study Of Gold Ore Deposits Of Aristantau For Resilience And Search Technologies For Its Processing, Kuvandik Sanakulov, Omon Fuzaylov, J.A. Kenbaeva May 2020

Study Of Gold Ore Deposits Of Aristantau For Resilience And Search Technologies For Its Processing, Kuvandik Sanakulov, Omon Fuzaylov, J.A. Kenbaeva

Gorniy vestnik Uzbekistana

The article presents the results of research of chemical, material, mineralogical and rational analyses of persistent gold-bearing ore of The aristantau Deposit. The re- sults of experiments indicated the content of sulfide sulfur, organic carbon, arsenic and antimony. As a result, the technological scheme included operations for oxidative firing of the flotation concentrate. Various forms of fine-grained gold were found in pyrite, arsenopyrite, and sphalerite.


A Novel Method For Making Titanium Dioxide For Photocatalytic Applications, Gary Wilson Apr 2020

A Novel Method For Making Titanium Dioxide For Photocatalytic Applications, Gary Wilson

Graduate Theses & Non-Theses

Titanium dioxide possesses near-ideal properties for large-scale application as a photocatalyst. It is cheap and abundant, nontoxic, and environmentally safe. However, it still suffers from logistical problems preventing its application in industry: namely, rapid electron-hole recombination and inability to utilize visible light. For nearly five decades researchers in this booming field have made numerous attempts to address these problems, doping and combining titanium dioxide with a wide range of materials. A novel ambient-temperature approach to synthesis and doping/modification of anatase-form titanium dioxide was attempted using both oxygen-rich and oxygen deprived synthetic routes. Reactants were exposed to various wavelengths of ultraviolet …


Fluvial Sediment Organic Matter Degradation Identified With Elemental And Isotopic Fate During Laboratory Incubation, Brenden Riddle Jan 2020

Fluvial Sediment Organic Matter Degradation Identified With Elemental And Isotopic Fate During Laboratory Incubation, Brenden Riddle

Theses and Dissertations--Civil Engineering

Fluvial sediment is well recognized as a critical factor in both carbon and nutrient budgets within stream systems. However, we find very few studies of reactivity and isotope enrichment for stream water from agricultural and urban streams and the class of substrate known as fluvial sediment organic matter. This study investigated the hypothesis that fluvial sediment is subject to degradation even though many previous studies have considered this class of substrate generally inert. Therefore we qualify that elemental and isotopic signatures of fluvial sediment organic matter should be considered potentially non-conservative when used in tracer studies. Methods applied to this …


Characterization And Electrochemical Performance Of Dopamine-Sensitized Titania Thin Films, Joshua Garay Jan 2020

Characterization And Electrochemical Performance Of Dopamine-Sensitized Titania Thin Films, Joshua Garay

Theses and Dissertations--Chemical and Materials Engineering

Sensitization of mesoporous titania films with dopamine and polydopamine for visible light photoelectrochemical activity is investigated. Sensitization effectiveness is compared with 8 mM dopamine solutions of varying pH (acidic, basic, and neutral), as well as with a basic polydopamine solution. Vibrational changes due to dopamine attachment are determined from detached powders by Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) is used to quantify organics attached. X-ray photoelectron spectroscopy (XPS) of intact films probes the chemically induced charge shift from dopamine attachment. Cyclic voltammetry identifies the irreversible dopamine oxidation and tin reduction voltages. Finally, chronoamperometric curves are used to compare …


Electron Tunneling And X-Ray Photoelectron Spectoscopy Studies Of The Superconductiong Properties Of Nitrogen-Doped Niobium Resonator Cavities, Eric M. Lechner, Basu Dev Oli, Junki Makita, Gianluigi Ciovati, Alex Gurevich, Maria Iavarone Jan 2020

Electron Tunneling And X-Ray Photoelectron Spectoscopy Studies Of The Superconductiong Properties Of Nitrogen-Doped Niobium Resonator Cavities, Eric M. Lechner, Basu Dev Oli, Junki Makita, Gianluigi Ciovati, Alex Gurevich, Maria Iavarone

Physics Faculty Publications

We use scanning tunneling microscopy (STM) and spectroscopy (STS), and x-ray photoelectron spectroscopy (XPS) to investigate the effect of nitrogen doping on the surface electronic and chemical structures of cutouts from superconducting Nb radio-frequency cavities. The goal of this work is to get insights into the fundamental physics and materials mechanisms behind the striking decrease of the surface resistance with the radio-frequency magnetic field, which has been observed on N-doped Nb cavities. Our XPS measurements reveal significantly more oxidized Nb 3d states and a thinner metallic suboxide layer on the N-doped Nb surfaces, which is also confirmed by tunneling spectroscopy …


Carbon Oxidation At The Atomic Level: A Computational Study On Oxidative Graphene Etching And Pitting Of Graphitic Carbon Surfaces, Simon Schmitt Jan 2020

Carbon Oxidation At The Atomic Level: A Computational Study On Oxidative Graphene Etching And Pitting Of Graphitic Carbon Surfaces, Simon Schmitt

Theses and Dissertations--Mechanical Engineering

In order to understand the oxidation of solid carbon materials by oxygen-containing gases, carbon oxidation has to be studied on the atomic level where the surface reactions occur. Graphene and graphite are etched by oxygen to form characteristic pits that are scattered across the material surface, and pitting in turn leads to microstructural changes that determine the macroscopic oxidation behavior. While this is a well-documented phenomenon, it is heretofore poorly understood due to the notorious difficulty of experiments and a lack of comprehensive computational studies. The main objective of the present work is the development of a computational framework from …


Oxidation Of Nickel And Nickel-Phosphorous Coated Aisi 430 Alloy: Effects Of Pre-Oxidation And Pre-Reduction, Mark Kevin King Jan 2020

Oxidation Of Nickel And Nickel-Phosphorous Coated Aisi 430 Alloy: Effects Of Pre-Oxidation And Pre-Reduction, Mark Kevin King

All ETDs from UAB

The solid oxide fuel cell (SOFC) electrochemically converts chemical energy into electrical energy. Interconnects are used to provide electrical connection to various individual cells in a stack for drawing useful electrical energy in the kW-MW range. By lowering the operation temperature to 800oC, the chromia-forming ferritic alloy interconnects become applicable. Their corrosion resistant chromia layer at the surface can form gaseous chromium oxides that lower the SOFC output by the cathode poisoning phenomena. Application of protective coatings can mitigate oxidation and form a resistant layer over the chromia. In this study, the electroless and electrolytic deposition methods were used to …