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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
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Date: May 2019
Creator: Wan, Yiyang
Item Type: Refine your search to only Thesis or Dissertation
open access

Fabrication of Large-Scale and Thickness-Modulated Two-Dimensional Transition Metal Dichalcogenides [2D TMDs] Nanolayers

Description: This thesis describes the fabrication and characterization of two-dimensional transition dichalcogenides (2D TMDs) nanolayers for various applications in electronic and opto-electronic devices applications. In Chapter 1, crystal and optical structure of TMDs materials are introduced. Many TMDs materials reveal three structure polytypes (1T, 2H, and 3R). The important electronic properties are determined by the crystal structure of TMDs; thus, the information of crystal structure is explained. … more
Date: May 2019
Creator: Park, Juhong
Item Type: Refine your search to only Thesis or Dissertation

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
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Date: May 2019
Creator: Mondal, Barnali
Item Type: Refine your search to only Thesis or Dissertation

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
open access

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

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
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Date: August 2019
Creator: Rathod, Urmilaben Pradipsinh P
Item Type: Refine your search to only Thesis or Dissertation

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
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Date: August 2019
Creator: Salloom, Riyadh Farooq
Item Type: Refine your search to only Thesis or Dissertation

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
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Date: August 2019
Creator: Soni, Vishal
Item Type: Refine your search to only Thesis or Dissertation

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
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Date: August 2019
Creator: Shukla, Shivakant
Item Type: Refine your search to only Thesis or Dissertation

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
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Date: December 2019
Creator: Hasannaeimi, Vahid
Item Type: Refine your search to only Thesis or Dissertation
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