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Showing 1 to 20 of 22 for “"ultra-high temperature ceramics"”.
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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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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
… 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 density increased of ~70% for uncoated …
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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
… a ceramic green body. For difficult-to-densify ceramics such as the UHTCs, which find their place in extreme environment applications, precise control of each step of the manufacturing process is key. In this work, a fundamental study on the interaction between particles in non-aqueous slip …
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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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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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Understanding How Tape Casting Titanium Diboride Shifts its Processing-Microstructure-Properties Paradigm Toward New Applications
… 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 first detailed studies to …
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Quantitative phase-field modeling of crack propagation in multi-phase materials
… crack propagation in polycrystalline composite ceramics capable of designing micro-architectures of phases to improve fracture toughness and damage tolerance of ZrB<sub>2</sub>-based ultra-high temperature ceramics (UHTCs). A quantitative phase-field model based on the regularized formulation of …
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Nano-scale Heat Transfer in Nanostructures: Toward Understanding and Engineering Thermal Transport
… could promote thermoelectricity. The study of high-temperature coating composite materials helps with the understanding of the role played by composition and the structural characterization, which is difficult to be approached by experiments. The method applied in studying the …
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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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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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Processes and Materials for Space Exploration and Colonization
… this regard, material research in the field of Ultra High Temperature Ceramics (UHTCs) is expected to contribute to the increase in performances of refractory parts that play an important role in rocket launchers and space vehicles. In this thesis work, new materials based on transition metal …
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Fusion welding of diboride-carbide ceramic composites
… to decrease with decreasing arc power. A high arc power resulted in high growth rates of ZrB<sub>2</sub> and a textured FZ, lower arc power FZs did not exhibit texture. A high current plasma arc (222 A) was used to increase the temperature of the weld pool, such that ZrB<sub>2</sub> growth …
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Elevated temperature mechanical properties of zirconium diboride based ceramics
… 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 vol% B₄ C (ZS); and ZrB₂ - 10 vol% ZrC (ZC). In argon, Z, ZS, and …
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Improving the oxidation resistance of diboride-based ceramics
… 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 the research, the …
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Effect of solid solutions and second phases on the thermal conductivity of zirconium diboride ceramics
… the thermal conductivity (k) of ZrB<sub>2</sub> ceramics. The goal was to develop a better understanding of how various solid solutions and second phases affect the thermal and electrical transport in ZrB<sub>2</sub>, with a focus on the effect of C, W, and ZrC. The first study showed C additions …
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Fabricating Complex-Shaped Components by Room-Temperature Injection Molding of Aqueous Ceramic Suspension Gels
… dense, near-net shape ceramic parts by room-temperature injection molding, a novel processing method based on traditional ceramic injection molding. This alternative method eliminated the need for heating and cooling feedstocks to process, as is required in conventional injection molding, …
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