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Showing 1 to 14 of 14 for “"ZrB2"”.
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The effect of Zr and ZrB2 additions to NdFeB alloys
… via additions of 0.6 at% of Zr or 1.0 at% of ZrB2 have been investigated by EPMA (Electron Probe Microanalysis) and TEM (Transmission Electron Microscopy). 1.0 at% of ZrB2 has been found to be very effective in suppressing the formation of free α-Fe dendrites during solidification, but 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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JOINING OF ULTRA-HIGH TEMPERATURE CERAMICS TO THE SAME AND REFRACTORY METALS VIA FUSION WELDING
… of molybdenum and a molybdenum alloy. SiC-ZrB2-ZrC ceramics on a binary join between pure SiC and the ternary eutectic composition were found to be weldable when SiC content was below ~57.5 vol%. Compositions above 57.5 vol% SiC were unweldable based on pitting and off-gassing behavior. …
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Advanced Synthesis of Ultra-High Temperature Ceramics (UHTCs) and High Temperature Electron Emitting Materials
… temperature ceramic (UHTC) zirconium diboride or ZrB2 was sintered by ultra-fast high temperature sintering (UHS). The UHS process was optimized and the sintering parameters for ZrB2 and other UHTCs were studied. ZrB2 is an ultra-high temperature ceramic (UHTC) with a very high melting point; …
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Remote Plasma Chemical Vapor Deposition of Zirconium Boride: Growth and Diffusion Barrier Characteristics
High-quality ZrB2 thin films have been deposited at substrate temperatures as low as 300°C by a new method: remote hydrogen plasma chemical vapor deposition from the single-source precursor zirconium borohydride, Zr(BH 4)4. Carrying out the deposition in the presence of atomic hydrogen …
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Near-Net Shaping and Additive Manufacturing of Ultra-High Temperature Ceramics via Colloidal Processing
… colloidal process for advanced ceramics such as ZrB2, and a case for a cyclohexane slip casting system resulting in low viscosity, shear-thinning behavior and green density of 64%, is made. The focus on non-aqueous colloidal processing is extended to gelcasting, involving three different sets of …
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Cerámicos refractarios a base de diboruro de circonio y aluminio: fabricación mediante SPS y caracterización
… se mezcló en proporción 1ZrH2:2B para obtener ZrB2 monolítico a una temperatura optima de sinterización de 1850ºC. “Sistema intermetálico”, se mezcló una ratio 2ZrH2:1B:1Al y se obtuvo un composite de aproximadamente 25%ZrB2-75%Zr3Al2 a una temperatura de 1175ºC. “Sistema nanoestructurado” se …
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Colloidal Processing, Microstructural Evolution, and Anisotropic Properties of Textured Ultra-High Temperature Ceramics Prepared Using Weak Magnetic Fields
… crystalline texture in TiB2 (LOF = 0.88) and ZrB2 (LOF = 0.79) along the direction of the magnetic field. Less texture was achieved in HfB2 (LOF = 0.39). In all cases, the density of the textured materials was less than that of control untextured materials, indicating that texturing hindered …
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Modeling and design of reload LWR cores for an ultra-long operating cycle
… - a thin fuel pellet surface coating of ZrB2) as burnable poisons to hold down excess reactivity and to control power peaking. The BWR employs only Gd203. Both core designs require higher worth control rods in order to meet shutdown safety requirements. Fuel performance issues were also …
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Base material electrocatalysts for oxygen cathodes in low temperature acid fuel cells
… passivated via growth of a resistive film and ZrB2, TiB2 corroded. The cathodic oxygen currents on sputter-deposited Ni/Ta/C, Co/Ta/C and Fe/Ta/C coatings on a carbon cloth support decreased by 20%, 23% and 30%, respectively when 1 M CH3OH was added to the 1.5 M H2SO4 electrolyte. This …
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Neutronic Characteristics of Using Zirconium Diboride and Gadolinium in a Westinghouse 17 X 17 Fuel Assembly
… coated with a thin layer of zirconium diboride (ZrB2). Other fuel manufacturers such as Combustion Engineering, Siemens, General Electric, and Framatome incorporate gadolinium directly into the fuel matrix which yields the gadolinium-uranium (Gd2O3 - UO2) integral burnable absorber (IBA) rods. A …
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Development of Materials for Extreme Environment Applications by Laser Powder Bed Fusion
… composite is then developed using 2 vol% ZrB2 as the reinforcing material. Microstructural results for this composite follow a similar trend to SiC and verify the capability for reducing porosity. Room temperature mechanical testing shows higher strength and lower ductility than the SiC. …
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Effect of solid solutions and second phases on the thermal conductivity of zirconium diboride ceramics
<p>"The research presented in this dissertation is focused on 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 …
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Microstructure Dual-Refinement and Mechanical Properties Manipulation of TiBw/TA15(Si) Composites by Thermo-mechanical Processing and Heat Treatment
… using spherical TA15 coarse powder and TiB2, ZrB2, and Si fine powders. Silicide particles precipitated on the α/β interfaces in the matrix, and the precipitation amount increased with the increase of Si and Zr element contents. The tensile strength of materials with different compositions …