UNT Theses and Dissertations - 144 Matching Results

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Determining the Emissivity of Roofing Samples: Asphalt, Ceramic and Coated Cedar

Description: The goal is to perform heat measurements examine of selected roofing material samples. Those roofing materials are asphalt shingles, ceramics, and cedar. It’s important to understand the concept of heat transfer, which consists of conduction, convection, and radiation. Research work was reviewed on different infrared devices to see which one would be suitable for conducting my experiment. In this experiment, the main focus was on a specific property of radiation. That property is the emissivit… more
Date: December 2015
Creator: Adesanya, Oludamilola
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Processing, Structure and Tribological Property Relations of Ternary Zn-Ti-O and Quaternary Zn-Ti-Zr-O Nanocrystalline Coatings

Description: Conventional liquid lubricants are faced with limitations under extreme cyclic operating conditions, such as in applications that require lubrication when changing from atmospheric pressure to ultrahigh vacuum and ambient air to dry nitrogen (e.g., satellite components), and room to elevated (>500°C) temperatures (e.g., aerospace bearings). Alternatively, solid lubricant coatings can be used in conditions where synthetic liquid lubricants and greases are not applicable; however, individual sol… more
Date: August 2014
Creator: Ageh, Victor
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Laser Deposition, Heat-treatment, and Characterization of the Binary Ti-xmn System

Description: The present research seeks to characterization of an additively manufactured and heat-treated Ti-xMn gradient alloy, a binary system that has largely been unexplored. In order to rapidly assess this binary system, compositionally graded Ti-xMn (0<x<15 wt%) specimens were fabricated using the LENS (Laser Engineered Net Shaping) and were subsequently heat-treated and characterized using a wide range of techniques. Microstructural changes with respect to the change in thermal treatments, hardness … more
Date: August 2013
Creator: Avasarala, Chandana
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Surface Degradation Behavior of Bulk Metallic Glasses and High Entropy Alloys

Description: In this study, the surface degradation behavior was studied for typical examples from bulk metallic glasses (BMGs), metallic glass composites (MGCs) and high entropy alloys (HEAs) alloy systems that are of scientific and commercial interest. The corrosion and wear behavior of two Zr-based bulk metallic glasses, Zr41.2Cu12.5Ni10Ti13.8Be22.5 and Zr57Cu15.4Ni12.6Al10Nb5, were evaluated in as-cast and thermally relaxed states. Significant improvement in corrosion rate, wear behavior, and friction c… more
Date: December 2017
Creator: Ayyagari, Venkata A
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Effect of Alloy Composition, Free Volume and Glass Formability on the Corrosion Behavior of Bulk Metallic Glasses

Description: Bulk metallic glasses (BMGs) have received significant research interest due to their completely amorphous structure which results in unique structural and functional properties. Absence of grain boundaries and secondary phases in BMGs results in high corrosion resistance in many different environments. Understanding and tailoring the corrosion behavior can be significant for various structural applications in bulk form as well as coatings. In this study, the corrosion behavior of several Zr-ba… more
Date: December 2015
Creator: Ayyagari, Venkata Aditya
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Corrosion Protection of Aerospace Grade Magnesium Alloy Elektron 43™ for Use in Aircraft Cabin Interiors

Description: Magnesium alloys exhibit desirable properties for use in transportation technology. In particular, the low density and high specific strength of these alloys is of interest to the aerospace community. However, the concerns of flammability and susceptibility to corrosion have limited the use of magnesium alloys within the aircraft cabin. This work studies a magnesium alloy containing rare earth elements designed to increase resistance to ignition while lowering rate of corrosion. The microst… more
Date: August 2013
Creator: Baillio, Sarah S.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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High Temperature Water as an Etch and Clean for SiO2 and Si3N4

Description: An environmentally friendly, and contamination free process for etching and cleaning semiconductors is critical to future of the IC industry. Under the right conditions, water has the ability to meet these requirements. Water becomes more reactive as a function of temperature in part because the number of hydronium and hydroxyl ions increase. As water approaches its boiling point, the concentration of these species increases over seven times their concentrations at room temperature. At 150 °C, … more
Date: December 2018
Creator: Barclay, Joshua David
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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A Study of Mechanisms to Engineer Fine Scale Alpha Phase Precipitation in Beta Titanium Alloy, Beta 21S

Description: Metastable b-Ti alloys are titanium alloys with sufficient b stabilizer alloying additions such that it's possible to retain single b phase at room temperature. These alloys are of great advantage compared to a/b alloys since they are easily cold rolled, strip produced and can attain excellent mechanical properties upon age hardening. Beta 21S, a relatively new b titanium alloy in addition to these general advantages is known to possess excellent oxidation and corrosion resistance at elevated t… more
Date: August 2013
Creator: Behera, Amit Kishan
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Nanohybrids Based on Solid and Foam Polyurethanes

Description: Polymer nanocomposites are a going part of Materials Science and Engineering. These new composite materials exhibit dimensional and thermal stability of inorganic materials and toughness and dielectric properties of polymers. Development of nanocomposites become an important approach to create high-performance composite materials. In this study silica, fly ash, silica nanotubes and carbon black particles have been added to modify polyurethane foam and thermoplastic polyurethanes. It has been fo… more
Date: May 2015
Creator: Bo, Chong
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Processing and Characterization of Nickel-Carbon Base Metal Matrix Composites

Description: Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are attractive reinforcements for lightweight and high strength metal matrix composites due to their excellent mechanical and physical properties. The present work is an attempt towards investigating the effect of CNT and GNP reinforcements on the mechanical properties of nickel matrix composites. The CNT/Ni (dry milled) nanocomposites exhibiting a tensile yield strength of 350 MPa (about two times that of SPS processed monolithic nickel… more
Date: May 2014
Creator: Borkar, Tushar Murlidhar
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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An Assessment of Uncommon Titanium Binary Systems: Ti-Zn, Ti-Cu, and Ti-Sb

Description: The current study focuses on phase stability and evolution in the titanium-zinc titanium-copper and titanium-antimony systems. The study utilized the Laser Engineering Net Shaping (LENS™) processing technique to deposit compositionally graded samples of three binary system in order to allow the assessment of phase stability and evolution as a function of composition and temperature the material is subjected to. Through LENS™ processing it was possible to create graded samples from Ti-xSb (up … more
Date: May 2015
Creator: Brice, David
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Processing of NiTi Shape Memory Alloys through Low Pressure and Low Temperature Hydrogen Charging

Description: Many industries including the medical, aerospace, and automobile industries have increasingly adopted the use of shape memory alloys (SMAs) for a plethora of applications due to their unique thermomechanical properties. From the commercially available SMAs in the market, binary NiTi SMAs have shown the most desirable properties. However, SMA properties can be significantly affected by the fabrication process. One of the most familiar applications of NiTi SMAs is in the design of actuating devic… more
Date: May 2018
Creator: Briseno Murguia, Silvia
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

The Effect of Processing Conditions on the Surface Morphology of Few-Layered WS2 Thin Films

Description: Recent progress in layered transition metal dichalcogenides (TMDs) has led to various promising electronic and optoelectronic applications. However, the structure of materials plays a critical role in electronic and optoelectronic devices, and determines performance. Electronic and optoelectronic devices typically consist of multiple layers that form electrical homojunctions or heterojunctions. Therefore, in a device it can be expected that a WS2 layer may serve as the substrate for a subseque… more
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Date: May 2019
Creator: Cai, Bimin
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Alloy Development and High-Energy X-Ray Diffraction Studies of NiTiZr and NiTiHf High Temperature Shape Memory Alloys

Description: NiTi-based shape memory alloys (SMAs) offer a good combination of high-strength, ductility, corrosion resistance, and biocompatibility that has served them well and attracted the attention of many researchers and industries. The alloys unique thermo-mechanical ability to recover their initial shape after relatively large deformations by heating or upon unloading due to a characteristic reversible phase transformation makes them useful as damping devices, solid state actuators, couplings, etc. H… more
Date: May 2018
Creator: Carl, Matthew A
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Carbon Nanotubes and Molybdenum Disulfide Protected Electrodes for High Performance Lithium-Sulfur Battery Applications

Description: Lithium-sulfur (Li-S) batteries are faced with practical drawbacks of poor cycle life and low charge efficiency which hinder their advancements. Those drawbacks are primarily caused by the intrinsic issues of the cathodes (sulfur) and the anodes (Li metal). In attempt to resolve the issues found on the cathodes, this work discusses the method to prepare a binder-free three-dimensional carbon nanotubes-sulfur (3D CNTs-S) composite cathode by a facile and a scalable approach. Here, the 3D structu… more
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Date: August 2019
Creator: Cha, Eunho
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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First Principles Calculations of the Site Substitution Behavior in Gamma Prime Phase in Nickel Based Superalloys

Description: Nickel based superalloys have superior high temperature mechanical strength, corrosion and creep resistance in harsh environments and found applications in the hot sections as turbine blades and turbine discs in jet engines and gas generator turbines in the aerospace and energy industries. The efficiency of these turbine engines depends on the turbine inlet temperature, which is determined by the high temperature strength and behavior of these superalloys. The microstructure of nickel based sup… more
Date: August 2012
Creator: Chaudhari, Mrunalkumar
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Surface Chemistry and Work Function of Irradiated and Nanoscale Thin Films Covered Indium Tin Oxides

Description: In this study, we used UV-ozone Ar sputtering, X-ray photoelectron and ultra-violet photoelectron spectroscopies and sputtering based depositions of RuO2 and Se nano-layers on indium tin oxides (ITOs). We elucidated the effect of Ar sputtering on the composition and chemistry of Sn rich ITO surface. We demonstrated that while a combination of UV-ozone radiation and Ar sputtering removes most of the hydrocarbons responsible for degrading the work function of ITO, it also removes significant amou… more
Date: May 2018
Creator: Che, Hui
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Atomistic Computer Simulations of Diffusion Mechanisms in Lithium Lanthanum Titanate Solid State Electrolytes for Lithium Ion Batteries

Description: Solid state lithium ion electrolytes are important to the development of next generation safer and high power density lithium ion batteries. Perovskite-structured LLT is a promising solid electrolyte with high lithium ion conductivity. LLT also serves as a good model system to understand lithium ion diffusion behaviors in solids. In this thesis, molecular dynamics and related atomistic computer simulations were used to study the diffusion behavior and diffusion mechanism in bulk crystal and gra… more
Date: August 2014
Creator: Chen, Chao-Hsu
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Design of a Polymeric Coating for Protecting Thermoelectric Materials from Sublimation and Oxidation

Description: Thermoelectric (TE) devices can undergo degradation from reactions in corrosive environments and at higher operating temperatures by sublimation and oxidation. To prevent the degradation, we have applied two high temperature polymers (HTPs) as coatings for TE materials. Sintering temperatures were from 250°C to 400°C. We explain why dip coating is better technique in our study and had two potential HTPs for tests. By applying TGA (thermogravimetric analysis), we were able to figure out which HT… more
Date: August 2019
Creator: Chen, I Kang
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Processing and Characterization of Polycarbonate Foams with Supercritical Co2 and 5-Phenyl-1H-tetrazole

Description: Since their discovery in the 1930s, polymeric foams have been widely used in the industry for a variety of applications such as acoustical and thermal insulation, filters, absorbents etc. The reason for this ascending trend can be attributed to factors such as cost, ease of processing and a high strength to weight ratio compared to non-foamed polymers. The purpose of this project was to develop an “indestructible” material made of polycarbonate (PC) for industrial applications. Due to the high … more
Date: May 2015
Creator: Cloarec, Thomas
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Microstructure for Enhanced Plasticity and Toughness

Description: Magnesium is the lightest metal with a very high specific strength. However, its practical applicability is limited by its toughness and reliability. Mg, being HCP has low ductility. This makes the improvement of toughness a grand challenge in Mg alloys. Friction stir processing (FSP) is a thermomechanical technique used to effect microstructural modification. Here, FSP was utilized to affect the toughness of WE43 sheets through microstructural modification. Room temperature Kahn-type tests wer… more
Date: August 2016
Creator: Das, Shamiparna
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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A Study of Power Generation From a Low-cost Hydrokinetic Energy System

Description: The kinetic energy in river streams, tidal currents, or other artificial water channels has been used as a feasible source of renewable power through different conversion systems. Thus, hydrokinetic energy conversion systems are attracting worldwide interest as another form of distributed alternative energy. Because these systems are still in early stages of development, the basic approaches need significant research. The main challenges are not only to have efficient systems, but also to conve… more
Date: August 2013
Creator: Davila Vilchis, Juana Mariel
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Dynamic Precipitation of Second Phase Under Deformed Condition in Mg-nd Based Alloy

Description: Magnesium alloys are the lightweight structural materials with high strength to weigh ratio that permits their application in fuel economy sensitive automobile industries. Among the several flavors of of Mg-alloys, precipitation hardenable Mg-rare earth (RE) based alloys have shown good potential due to their favorable creep resistance within a wide window of operating temperatures ranging from 150°C to 300°C. A key aspect of Mg-RE alloys is the presence of precipitate phases that leads to str… more
Date: December 2013
Creator: Dendge, Nilesh Bajirao
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Molecular Dynamics Simulations of the Structure and Properties of Boron Containing Oxide Glasses: Empirical Potential Development and Applications

Description: Potential parameters that can handle multi-component oxide glass systems especially boron oxide are very limited in literature. One of the main goals of my dissertation is to develop empirical potentials to simulate multi-component oxide glass systems with boron oxide. Two approaches, both by introducing the composition dependent parameter feature, were taken and both led to successful potentials for boron containing glass systems after extensive testing and fitting. Both potential sets can pro… more
Date: December 2017
Creator: Deng, Lu
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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