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.
Results
Showing 1 to 20 of 21 for “"ZrC"”.
-
Multiscale corrosion of zirconium carbide, carbon, and CF/ZRC under extreme environments
… system materials, including zirconium carbide (ZrC), disordered carbons, and carbon fiber/zirconium carbide (Cf/ZrC) composites. Initial analysis focused on the ultra-high temperature oxidation behavior of hot-pressed substoichiometric zirconium carbide in a highly controlled test environment. …
-
Analysis of U-Zr-C-O Quaternary System for Applications in Advanced ZRC Coated Triso Particles
<p>The implementation of ZrC for use in oxide TRISO particles for Very High Temperature Reactor (VHTR) conditions to prevent kernel overpressurization and kernel migration has been proposed by several researchers. Analysis is performed incorporating first-principles thermodynamics along with …
-
The Deposition Characteristics of Zrc On Uo2 Kernels Produced For Advanced Triso Fuels In Gen-Iv Reactors
… TRISO particle in which zirconium carbide (ZrC) layer is placed directly on the fuel kernel. The benefit of adding ZrC is that it is a good oxygen getter due to a low Gibb's free energy, forming a stable zirconium oxide and free carbon. This will help minimize typical TRISO fuel failures of …
-
Microstructural evolution of zirconium carbide (ZrCₓ) ceramics under irradiation conditions
… microstructural evolution of Zirconium Carbide (ZrC<sub>2</sub>) ceramics under irradiation conditions is required for their successful implementation in advanced Gen-IV gas-cooled nuclear reactors. The research presented in this dissertation focusses on elucidating the ion and electron …
-
Sintering techniques for microstructure control in ceramics
… strength of composites up to 590MPa at 50wt% ZrC, significantly higher than the flexural strength of 380MPa observed in similarly prepared ZrB<sub>2</sub> – SiC. This difference was attributed to the absence of CTE mismatch induced residual stresses in the ZrB<sub>2</sub> – ZrC composites. A …
-
Non-stoichiometry and radiation damage effects in zirconium carbide and layered carbide ceramics for nuclear fuel cladding applications
Sub-stoichiometric Zirconium Carbide (ZrC) is a viable candidate for use in nuclear environments as it has shown desirable thermo-physical properties and an ability to tolerate radiation damage. These thermophysical properties, in some cases, are sensitive to stoichiometry making ZrC a customisable …
-
Coating Parameters of Zirconium Carbide On Advanced Triso Fuels
… SiC TRISO coatings with an additional layer of ZrC applied directly to the UO2 fuel kernel. The additional ZrC layer will act as an oxygen getter to prevent failure mechanisms experienced in TRISO particles. Two failure mechanisms that are of the most concern are the over pressurization of the …
-
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. Welded …
-
The Effect of Coating Parameters On Advanced TRISO Fuels With Zirconium Carbide
… To negate these problems a solution of adding a ZrC gettering layer between the kernel and PyC buffer layer has been proposed. The purpose of this study is to provide insight into the coating parameters and how they affect the coating properties. Advanced TRISO coatings consisting of a ZrC getter …
-
First principles phase diagram calculations in group IV carbides and Mg2SiO4 liquid from Molecular Dynamics
… phase diagrams of the binary systems TiC-ZrC, TiC-HfC, ZrC-HfC at ambient pressure are computed based on electronic structure and energy calculations within density functional theory. Formation energies for a large number of supercells with compositions of (M1,M2)C, M1, M2 = Ti, Zr, or Hf, …
-
Characterization of Uranium Carbide Microspheres In An Inert Zirconium Carbide Matrix For Gas Fast Reactors
… Uranium Carbide (UC) and Zirconium Carbide (ZrC) have been characterized and studied. Uranium carbide (UC) microspheres produced in the USC-Nuclear Materials Laboratory were subjected to metallographic techniques, and then characterized by analytical methods. A method for separation of …
-
Effect of solid solutions and second phases on the thermal conductivity of zirconium diboride ceramics
… with a focus on the effect of C, W, and ZrC. The first study showed C additions improved densification and it was proposed that the reduction of boria was the impetus for this result. Boron carbide was formed by the reaction of excess C with reduced B and its formation was mitigated by …
-
The Irradiation Tolerance of Zirconium-based MAX Phases
… MAX phase-based ceramic material with 33 wt.% ZrC has been irradiated with 22 MeV Au7+ ions between room temperature and 600oC, achieving a maximum nominal midrange dose of 3.5 displacements per atom. Under room temperature irradiation, the ions caused a partial amorphisation of the MAX phase. …
-
Understanding How Tape Casting Titanium Diboride Shifts its Processing-Microstructure-Properties Paradigm Toward New Applications
… (2 wt% PCN-222). Synthesis of uniform, spherical ZrC is difficult and generally not cost-effective, as is the case for most ultra-high temperature ceramics. High aspect ratio particles for reinforcement of ceramic composites are even more difficult to synthesize. Metal organic frameworks (MOF) are …
-
Atomistic simulation of strength and deformation of ceramic materials
… described by pairwise ionic interactions and ZrC with many-body covalent interactions. These range from stress-strain responses to various applied loading, determination of fracture toughness, structural relaxation effects, to scaling with grain size. Additionally, a study of the thermal …
-
Fusion welding of diboride-carbide ceramic composites
… 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 resulted in a keyhole fusion zone (full penetration), the arc to workpiece power …
-
Solution-based synthesis and processing of nanocrystalline ZrB₂-based composites
… B/Zr = 3.0. ZrB₂-based composite powders with ZrC, ZrO₂, TaB₂, TaC, SiC, TaSi₂ and B₄C were prepared with particle sizes of 10-500 nm for different phases based SEM micrographs. The composite powders were highly sinterable with proper processing methods developed to avoid and remove oxide …
-
CRUD resistant fuel cladding materials
… nanoparticulate CRUD precursors. After testing, ZrC was the only material out of six that did not develop dark, circular spots, which are hypothesized to be the beginnings of CRUD boiling chimneys. Further testing will be needed to confirm that it is indeed more CRUD resistant, even under …
-
Elevated temperature mechanical properties of zirconium diboride based ceramics
… vol% SiC - 2 vol% B₄ C (ZS); and ZrB₂ - 10 vol% ZrC (ZC). In argon, Z, ZS, and ZC had strengths of 210 (at 2300ºC), 260 (at 2200ºC), and 295 MPa (at 2300ºC), the highest temperatures tested for each composition. Fractography was used extensively to characterize the strength limiting flaws as a …
-
Thermodynamic and Thermochemical Investigation of Advanced Triso Coated Particle Fuels
… to evaluate the oxygen gettering ability of ZrC and SiC. It was further used to evaluate methods to control the oxygen partial pressure in experiments over a range of values representative of the TRISO fuel (10-8~10-6atm). This work was done in support of developing capabilities for future …
Page 1 of 2