Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 69 for “"Diboride"”.
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Magnesium Diboride Superconducting Devices and Circuits
While magnesium diboride (MgB2) was first synthesized in the 1950s, MgB2’s superconductive properties were not discovered until 2001. It has the highest superconducting transition temperature of all the metallic superconductors at ~39 K at atmospheric pressure. MgB2 is also unique in that it has a …
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Fusion welding of diboride-carbide ceramic composites
<p>"Plasma and pulsed plasma arc welding (PAW and PPAW) processes were used to fusion weld ZrB<sub>2</sub> containing 20 vol% ZrC. Varying welding parameters resulted in changes in weld pool shape and size, and the size of ZrB<sub>2</sub> grains within the fusion zone. For PAW processes that …
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Improving the oxidation resistance of diboride-based ceramics
<p>"Oxidation behavior has restricted the development of ZrB₂-based ceramics for aerospace and hypersonic flight vehicles applications. The research presented in this dissertation focuses on the effect of transition metal (TM) additives on oxidation behavior of ZrB₂ ceramics. In the first stage of …
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Enhancement of superconductivity in Magnesium Diboride nano-structures
For many years scientists have tried different strategies to improve superconductivity. The recent development in the growth of thin films and grains at the nanoscale has allowed to measure in certain materials critical temperatures that differ from the bulk values. At the same time these results …
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Improving the thermal shock resistance of zirconium diboride ceramics
… the thermal shock resistance of zirconium diboride (ZrB₂) based ceramics. Despite the development of ZrB₂-based materials for their use in high temperature applications, the thermal shock properties have not been investigated extensively. Materials expected to be used in ultra-high …
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Elevated temperature mechanical properties of zirconium diboride based ceramics
<p>"Research presented in this dissertation focused on the mechanical behavior of ZrB₂ based ceramic at elevated temperatures. Flexure strength, fracture toughness, and elastic modulus were measured at temperatures up to 2300ºC for three compositions: monolithic ZrB₂ (Z); ZrB₂ - 30 vol% SiC - 2 …
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Processing and characterization of boron carbide-hafnium diboride ceramics
<p>"Hafnium diboride based ceramics are promising candidate materials for advanced aerospace and nuclear reactor components. The effectiveness of boron carbide and carbon as HfB₂ sintering additives was systematically evaluated. In the first stage of the research, boron carbide and carbon additives …
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Pressureless Densification of Alumina - Titanium Diboride Ceramic Matrix Composites
The research focus was to determine diffusion mechanisms responsible for densification behavior of SHS produced Al2O3/TiB2 Ceramic Matrix Composites (CMCs). Previous research has shown SHS produced Al₂O₃/TiB₂ composites exhibited unique microstructural properties that contributed to high strength, …
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Stress measurement and development of zirconium diboride-silicon carbide ceramics
"Research presented in this dissertation focused on the production of ZrB₂-SiC composites and their characterization; in particular their mechanical properties and thermally generated residual stresses. Thermally generated stresses were measured using Raman spectroscopy as well as both neutron and …
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Reaction Synthesis of Titanium Aluminide / Titanium Diboride in-Situ Composites
Reaction synthesis is a processing technique where the thermal activation energy needed to form a compound is provided by the exothermic heat of formation of the thermodynamically stable product. This type of synthesis has been used to form a variety of ceramics, intermetallics, and in-situ …
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Aligned Continuous Cylindrical Pores Derived from Electrospun Polymer Fibers in Titanium Diboride
… multi-scale porous structures in titanium diboride (TiB2) is investigated in this work. The introduction of electrospun PS fibers as a sacrificial filler into a colloidal suspension of TiB2 allows for easy control over the pore size, porosity, and long range ordering of the porous …
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Densification, microstructure, and mechanical properties of zirconium diboride based ultra-high temperature ceramics
"The first part of this dissertation was aimed at studying the densification of ZrB₂ ceramics by pressureless sintering techniques. Various processes have been applied to coat ZrB₂ powders with polymer precursors, which were used to produce C after charring. After sintering at 1900⁰C, relative …
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Effect of solid solutions and second phases on the thermal conductivity of zirconium diboride ceramics
… aimed at understanding thermal transport in diboride based materials"--Abstract, page iv.</p>
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Processing, microstructure, and mechanical properties of zirconium diboride-molybdenum disilicide ceramics and dual composite architectures
<p>"This research had two objectives: characterization of processing-microstructure-mechanical property relationships of conventional ZrB<sub>2</sub>-MoSi<sub>2</sub> ceramics at room temperature (RT) and 1500⁰C in air, and fabrication of ZrB<sub>2</sub>-MoSi<sub>2</sub> dual composite …
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Chemical Vapor Deposition of Metal Diboride and Metal Oxide Thin Films From Borohydride-Bonded Precursors
… shift away from the MgB2 structure to the diboride structure of the catalyst metal, suggesting that Mg is partially substituted by the corresponding metals.
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Tribological Behavior of Cvd-Grown Hafnium Diboride Thin Films From Macro to Nano-Length Scales
Made available in DSpace on 2015-09-25T20:53:10Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3337722.pdf: 3158668 bytes, checksum: 49752af5170943f48ee6443a1fd3ecd3 (MD5) Previous issue date: 2008
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Thermal conductivity and electrical resistivity of cemented carbides, titanium diboride and high temperature ceramic superconductors
… grains. In high purity polycrystalline titanium diboride it is found that scattering of phonons and electrons from defects is an important cause of thermal resistivity. The scattering centers are boron vacancies and particles of elemental carbon."
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Developing fully mixed oxidation-resistant hafnium aluminum diboride hard coatings deposited by low temperature CVD
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01
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Understanding How Tape Casting Titanium Diboride Shifts its Processing-Microstructure-Properties Paradigm Toward New Applications
… beyond aerospace. One of the UHTCs, titanium diboride (TiB2) exhibits high electrical and thermal conductivity that could satisfy the needs of functional ceramic component applications, like battery cathodes, by tailoring its microstructure and architecture. This thesis represents one of the …
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