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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Laser Deposition, Heat-treatment, and Characterization of the Binary Ti-xmn System

Avasarala, Chandana 08 1900 (has links)
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 and chemical composition were observed and will be presented. These include assessments of both continuous cooling, leading to observations of both equilibrium and metastable phases, including the titanium martensites, and to direct aging studies looking for composition regimes that produce highly refined alpha precipitates – a subject of great interest given recent understandings of non-classical nucleation and growth mechanisms. The samples were characterized using SEM, EDS, TEM, and XRD and the properties probed using a Vickers Microhardness tester.
12

On-line inspection and thermal properties comparison for laser deposition process

Yang, Yu, January 2007 (has links) (PDF)
Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 6, 2007) Includes bibliographical references.
13

Orientation of MgO thin films on Si(001) prepared by pulsed laser deposition

Zhu, Tie-Jun, Lu, Li 01 1900 (has links)
Pulsed laser deposition method was employed to grow MgO thin films with preferred orientation on bare Si(100) and SiO₂/Si(100) substrates. The orientation of MgO thin films was systematically investigated by varying deposition parameters. XRD analysis showed that the preferred orientation of MgO thin films would change from (111) to (100) when laser fluence decreased and oxygen pressure increased to certain extend. But it was difficult to fabricate completely (100)-oriented MgO films. Substrate temperature seemed to have little influence on the orientation of MgO thin films at high laser fluence. SEM images of the MgO thin films on Si(100) deposited at 400°C and the laser fluence of 5J/cm² in the oxygen ambient of 200mTorr demonstrated that there was no presence of interfacial reactions or cracks and the film surface was very smooth. Such film is suitable as buffer layers for the growth of high-quality ferroelectric and superconducting overlayers. / Singapore-MIT Alliance (SMA)
14

Investigation on Thin Film Lithium Microbatteries

Shi, Z., Lü, L., Ceder, Gerbrand 01 1900 (has links)
Thin film lithium microbatteries were investigated in this project in which LiCoO₂ cathodes about 200 to 500 nm were fabricated by pulsed-laser deposition (PLD) at different processing parameters such as laser energy and fluence, substrate temperature, background gas pressure, and target-substrate distance. Structure, microstructure and composition of as-deposited LiCoO₂ films were determined by XRD, SEM and XPS. Optimal deposition parameters were identified. Relaxation of open-circuit voltage of as-prepared cells and charge-discharge cycling were conducted to characterize the electrochemical properties of microbatteries made of these LiCoO₂ films. / Singapore-MIT Alliance (SMA)
15

Process models for laser engineered net shaping

Kummailil, John. January 2004 (has links)
Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: rapid prototyping; solid freeform fabrication; LENS; laser engineered net shaping; laser; titanium. Includes bibliographical references (p. 83-85).
16

Growth and characterization of wide-gap semiconducting oxide and chalcogenide thin films by pulsed laser deposition /

Newhouse, Paul F. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Some pages left blank intentionally. Includes bibliographical references (leaves 125-130). Also available on the World Wide Web.
17

Laser-assisted diamond deposition in open atmosphere

Han, Yaoxuan. January 2008 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Nov. 20, 2008). PDF text: xvii, 187 p. : ill. (some col.) ; 11 Mb. UMI publication number: AAT 3311304. Includes bibliographical references. Also available in microfilm and microfiche formats.
18

Analysis of heat transfer in subcooled metal powder subjected to pulsed laser heating

Konrad, Chad E. January 2005 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 14, 2006) Includes bibliographical references.
19

Characterization of LiNi₀.₅Mn₁.₅O₄ Thin Film Cathode Prepared by Pulsed Laser Deposition

Xia, Hui, Lu, Li, Ceder, Gerbrand 01 1900 (has links)
LiNi₀.₅Mn₁.₅O₄ thin films have been grown by pulsed laser deposition (PLD) on stainless steel (SS) substrates. The crystallinity and structure of thin films were investigated by X-ray diffraction (XRD). Microstructure and surface morphology of the thin films were examined using a field-emission scanning electron microscope (FESEM). The electrochemical properties of the thin films were studied with cyclic voltammetry (CV) and galvanostatic charge-discharge in the potential range between 3.0 and 4.9 V. The electrochemical behavior of LiNi₀.₅Mn₁.₅O₄ thin films showed reversible capacity above 4.7 V and good cycle performance up to 50 cycles. / Singapore-MIT Alliance (SMA)
20

THE FABRICATION OF HEUSLER ALLOY THIN FILMS FROM MULTIPHASE TARGETS USING PULSED LASER DEPOSITION

Patton, Heather M. A. 01 January 2009 (has links)
In this project, we have explored the possibility of growing high quality Heusler alloy thin films from multiphase targets. Bulk targets were found to be partially formed, i.e. not of homogeneous L21 structure, through x-ray diffraction measurements. Pulsed laser deposition is a technique that can provide a congruent transfer of material from the target to the substrate, even in some cases where the target is not of a single crystalline phase. It was the objective of this work to determine whether L21 structured thin films of Co2MnAsxGe(1-x) could be grown from multiphase targets. Measurements have been carried out to study the magnetic and structural properties of the Heusler alloys Co2MnAsxGe(1-x). The optimization parameters that were investigated were substrate type, growth temperature, laser parameters, film thickness, and other common deposition parameters. Temperature-dependent magneto-optic Kerr effect (MOKE) techniques were used to study the qualitative magnetic properties. Alternating current (AC) susceptibility (using a MOKE technique) measurements were made as a function of temperature to view the second-order transition and obtain the Curie temperatures. Frequency dependent AC susceptibility was measured to determine the frequency dependence of the AC susceptibility for Co2MnAsxGe(1-x).

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