UNT Libraries - 12 Matching Results

Search Results

Results: 1 - 12
Note: All results matching your query require you to be a member of the UNT Community (you must be on campus or login with university credentials for access).

Bio-Inspired Material Surfaces with Self-cleaning, Micromanipulation and Water Collection

Description: Geckos are famous for the skill of switchable adhesion that they use to stick on various surface while keep their fingers super clean. In the dissertation, a unique mechanism was discovered to explain gecko self-cleaning phenomena. Using atomic force microscopy (AFM), we managed to compare the microparticle-substrate adhesion and the microparticle-seta adhesion with a single seta bonded to the AFM cantilever. A dynamic effect was approved that high pulling-off speed could increase the micropart… more
Date: May 2019
Creator: Wan, Yiyang

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
Date: August 2019
Creator: Cha, Eunho

Charpy Impact Testing of Twinning Induced Plasticity and Transformation Induced Plasticity High Entropy Alloys

Description: High entropy alloys (HEAs) are a new class of solid solution alloys that contain multiple principal elements and possess excellent mechanical properties, from corrosion resistance to fatigue and wear resistance. Even more recently, twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) non-equiatomic high entropy alloys have been engineered, promising increased strength and ductility as compared to their equiatomic counterparts. However, impact and fracture resistance o… more
Date: August 2019
Creator: Zellner, Samantha R

Dynamic Deformation and Shear Localization in Friction-Stir Processed Al0.3CoCrFeNi and Fe50Mn30Co10Cr10 High-Entropy Alloys

Description: High entropy alloys (HEAs) are a relatively new class of solid solution alloys that contain multiple principal elements to take advantage of their high configurational entropy, sluggish diffusion, lattice distortion, and the cocktail effect. In recent development, work hardening mechanisms known as twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) have been found active in Al0.3CoCrFeNi (molar fraction) and Fe50Mn30Co10Cr10 (at %) HEA compositions. Friction-stir pr… more
Date: August 2019
Creator: Macdonald, Neil

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
Date: May 2019
Creator: Cai, Bimin

Extrinsic Doping of Few Layered Tungsten Disulfide Films by Pulsed Laser Deposition

Description: This dissertation tested the hypothesis that pulsed laser deposition (PLD) could be used to create targeted dopant profiles in few layered WS2 films based on congruent evaporation of the target. At the growth temperatures used, 3D Volmer-Weber growth was observed. Increased energy transfer from the PLD plume to the growing films degraded stoichiometry (desorption of sulfur) and mobility. Sulfur vacancies act as donors and produce intrinsic n-type conductivity. Post deposition annealing signific… more
Date: August 2019
Creator: Rathod, Urmilaben Pradipsinh P

Nano-Manufacturing of Catalytic Amorphous Alloys

Description: In this dissertation, nano-manufacturing of amorphous alloys for electro-catalytic applications is reported and the role of chemistry and active surface area on catalytic behavior is discussed. The catalytic activity of recently developed platinum and palladium-based metallic glasses was studied using cyclic voltammetry and localized electrochemical techniques. The synergistic effect between platinum and palladium was shown for amorphous alloys containing both these elements. The mechanism for … more
Date: December 2019
Creator: Hasannaeimi, Vahid

Phase Transformation and Elastic Constants in Binary Titanium Alloys: An Atomistic Study

Description: The current understanding of the mechanical properties and deformation behavior of some individual phases in titanium alloys is limited due to the fine scale at which these phases precipitate within the β-phase matrix. The α and ω phases represent the most widely observed phases in titanium alloys depending on the alloy composition and also the heat treatment procedure adopted during processing. The possibility of precipitating ω-phase depends on the content of the β-stabilizers within the syst… more
Date: August 2019
Creator: Salloom, Riyadh Farooq

Phase Transformations in Refractory High Entropy Alloys

Description: High entropy alloys (HEAs) based on refractory elements have shown a great potential for high temperature structural applications. In particular, the ones containing Al, exhibits a microstructure similar to the γ-γ' in Ni-based superalloys. While these alloys exhibit impressive strengths at room temperature (RT) and at elevated temperatures, the continuous B2 matrix in these alloys is likely to be responsible for their brittle behavior at RT. Phase stability of five such alloys are studied by t… more
Date: August 2019
Creator: Soni, Vishal

Process-Structure-Property Relationships in Friction Stir Welded Precipitation Strengthened Aluminum Alloys

Description: Through a series of carefully designed experiments, characterization and some modeling tools, this work is aimed at studying the role of thermal profiles on different microstructural zones and associated properties like strength and corrosion through a variation of weld parameters, thermal boundary conditions and material temper. Two different alloys belonging to the Al-Cu and Al-Cu-Li system in different temper conditions- peak aged (T8) and annealed (O) were used. A 3D-thermal pseudo mechanic… more
Date: May 2019
Creator: Mondal, Barnali

Processing-Structure-Property Relationships of Reactive Spark Plasma Sintered Boron Carbide-Titanium Diboride Composites

Description: Sintering parameter effects on the microstructure of boron carbide and boron carbide/titanium diboride composites are investigated. The resulting microstructure and composition are characterized by scanning electron microscopy (SEM), x-ray microscopy (XRM) and x-ray diffraction (XRD). Starting powder size distribution effects on microstructure are present and effect the mechanical properties. Reactive spark plasma sintering introduces boron nitride (BN) intergranular films (IGF's) and their eff… more
Date: August 2019
Creator: Lide, Hunter

Understanding the Micromechanism of Cyclic Loading Behavior of Ultrafine Grained Alloys

Description: In the current study, we have investigated the cyclic loading behavior of conventional as well as novel alloy system exhibiting fine and ultrafine-grained structure. While in case of conventional alloy systems (here aluminum alloy AA5024), the effect of three different grain sizes was investigated. Improvement in fatigue properties was observed with decreasing grain size. The unique microstructure produced via Friction stir processing was responsible for the improved fatigue response. Additiona… more
Date: August 2019
Creator: Shukla, Shivakant
Back to Top of Screen