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 54 for “"Ultra-high Temperature"”.
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Reaction processing for the development of ultra-high temperature ceramics
"Research into ultra high temperature materials has increased in recent years due to the need for material systems that can withstand the temperatures associated with hypersonic flight applications. ZrB₂ and HfB₂ are among the candidates for these extreme conditions. These diborides have melting …
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Design Challenges for Ultra-High-Temperature Energy Storage with Thermophotovoltaics
… are suited to this task, partially due to their high cost, rare constituent materials, and geographic constraints. This thesis investigates several pressing design challenges for a new electrical energy storage technology, termed Thermal Energy Grid Storage (TEGS), with the potential for low cost …
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On Ultra-High Temperature Metamorphism in the Mid-Lower Crust
… The complex is an excellent natural example of ultra-high temperature (UHT) metamorphic processes and country rock-magma interaction due to mappable units of hybrid igneous rocks and the presence of large, partially melted, politic "emery" xenoliths. Previous attempts to understand the formation …
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Thermomechanical Modeling of Oxidation Effects in Porous Ultra-High Temperature Ceramics
… strains of up to 30% were applied at room temperature. The 10% and 40% RVEs showed shear banding and subsequent shear failure of the inter-pore struts, while shear banding in 70% RVE weakened the struts, which lead to buckling failure. A snapshot oxidation model was then applied to the …
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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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Ultra-high-temperature processed and conventionally processed milk in the preparation of instant pudding
Instant puddings were prepared using ultra-high-temperature (UHT) processed and conventionally (HTST) processed milk at 6°C and 23°C in six replicates of a 2X2 factorial design to determine the effect of milk type and temperature on apparent viscosity and gel strength of pudding. Apparent viscosity …
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Advanced Synthesis of Ultra-High Temperature Ceramics (UHTCs) and High Temperature Electron Emitting Materials
… have the inherent capability to resist extreme temperatures, high thermal shock due to high heat flux, and high oxidation and ablation. First, the ultra-high temperature ceramic (UHTC) zirconium diboride or ZrB2 was sintered by ultra-fast high temperature sintering (UHS). The UHS process was …
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Near-Net Shaping and Additive Manufacturing of Ultra-High Temperature Ceramics via Colloidal Processing
Ceramic colloidal processing routes such as slip casting, gelcasting and direct ink writing provide valuable insight into the role of interaction forces between particles, solvents, and polymeric additives in the rheology, particle packing, and strength of a ceramic green body. For …
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JOINING OF ULTRA-HIGH TEMPERATURE CERAMICS TO THE SAME AND REFRACTORY METALS VIA FUSION WELDING
<p>"This research focuses on the joining of ultra-high temperature ceramics to either themselves or refractory metals/alloys via fusion welding and the mechanical strength of produced joints. The ceramics studied consisted of compositions within a diboride-carbide-carbide ternary system while …
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Colloidal Processing, Microstructural Evolution, and Anisotropic Properties of Textured Ultra-High Temperature Ceramics Prepared Using Weak Magnetic Fields
The texturing of ultra-high temperature ceramics (UHTCs) using weak magnetic fields is studied and developed for the first time. Textured UHTCs were prepared by magnetically assisted slip casting (MASC) in weak magnetic field (B ~ 0.5 T). Analytical calculations describing the balance of torques …
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Investigating the Thermo-Mechanical Behavior of Highly Porous Ultra-High Temperature Ceramics using a Multiscale Quasi-Static Material Point Method
Ultra-high temperature ceramics (UHTCs) are a class of materials that maintain their structural integrity at high temperatures, e.g. 2000 °C. They have been limited in their aerospace applications because of their relatively high density and the difficulty involved in forming them into complex …
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ZrB2-SiC Based Ultra High Temperature Ceramic Composites: Mechanical Performance and Measurement and Design of Thermal Residual Stresses for Hypersonic Vehicle Applications
Ultra-high temperature ceramics (UHTCs), such as ZrB2-based ceramic composites, have been identified as next generation candidate materials for leading edges and nose cones in hypersonic air breathing vehicles. Mechanical performance of ceramic composites play an important role in the ultra-high …
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Heat Transfer and Thermal Process Design in Scraped-Surface Heat Exchangers
… scraped-surface heat exchanger (SSHE) for use in ultra-high temperature processing of low-acid liquid foods was evaluated using a Contherm 6 x 2 pilot-scale unit. Independent variables tested were steam pressure, blades rotational speed, inlet
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Multiscale corrosion of zirconium carbide, carbon, and CF/ZRC under extreme environments
… materials often fail. In the context of high-temperature air environments, such as those seen in hypersonics, highly reactive gas species, such as oxygen, are a primary mechanism by which most protection system materials degrade during service. This ultimately leads to changes in …
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Improving the thermal shock resistance of zirconium diboride ceramics
… 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 temperature environments (i.e. rocket propulsion and hypersonic flight) will be required to maintain …
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Active Measurement of a Micron-Order Gap Under High-Speed and High-Temperature Conditions
… to their excellent thermomechanical properties, ultra-high-temperature ceramics (UHTCs) have risen as a promising solution to act as a protective barrier between the harsh environment and surface materials of these flight bodies. The mechanical operation of a portable hypersonic simulation device …
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Solution-based synthesis and processing of nanocrystalline ZrB₂-based composites
… diboride/carbide composites are of interest for ultra-high temperature applications requiring improved thermomechanical and thermochemical stability. This thesis focuses on the synthesis, processing and sintering of nanocrystalline powders with Zr- and Ta-based diboride/carbide/silicide …
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Thermomechanical property evaluation of molybdenum alloys
The ultra high temperature structural intermetallic molybdenum and its alloys were studied for their thermal properties and correlated to the material microstructure. Thermal expansion tests were carried out using thermo-mechanical analyzer (TMA). Thermo cycling tests were conducted around …
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Microstructures and oxidation properties in hafnium-tantalum-nitride ceramics
Ultra high temperature ceramics (UHTC) comprise a class of materials characterized by high melting points, chemical inertness, high hardness, and moderate oxidation. These ceramics typically comprise either group IV or V metals bonded with boron, carbon or nitrogen. When in equal atomic ratio, a MX …
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Chemical and physical changes resulting from UHT treatment of milk
… of milk were taken at each heat treatment temperature. The serum was separated by rennin coagulation of the caseins and the heat denatured serum proteins. A fluorometric method of analysis for total sulfhydryl content of milk serum was developed that was rapid and sensitive to changes in …
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