{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/140546"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/140546","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Novel Synthesis and Characterization of Uranium-Zirconium Carbonitride by Direct Casting","abstract":"UZrCN has exhibited thermophysical properties beneficial to high temperature reactor applications such as nuclear thermal rockets. The present work investigates a novel liquid phase synthesis method involving the admission of nitrogen gas during arc melting of uranium, zirconium, and carbon. Initial microstructural examinations using scanning electron microscopy indicated that the samples remain heterogenous with zirconium-rich cores in a uranium-rich matrix. Heterogeneity resulted from large differences in melting temperature of the major constituents and rapid solidification. Additional energy dispersive x-ray spectroscopy, combustion analysis, and inert gas fusion analysis proved that the core regions have both uranium and zirconium and establish that carbon and nitrogen are retained during the fabrication process. Powder x-ray diffraction analysis clarifies that the light elements did not form compounds with the uranium matrix but rather incorporated into the core region forming a sub-stoichiometric UZrCN. Heat treatment performed on equimolar U-Zr-C resulted in an increase in the homogenous phase present with a diffraction pattern reflecting a ternary UZrCN despite small amounts of segregation in the final button.","abstract_html":"UZrCN has exhibited thermophysical properties beneficial to high temperature reactor applications such as nuclear thermal rockets. The present work investigates a novel liquid phase synthesis method involving the admission of nitrogen gas during arc melting of uranium, zirconium, and carbon. Initial microstructural examinations using scanning electron microscopy indicated that the samples remain heterogenous with zirconium-rich cores in a uranium-rich matrix. Heterogeneity resulted from large differences in melting temperature of the major constituents and rapid solidification. Additional energy dispersive x-ray spectroscopy, combustion analysis, and inert gas fusion analysis proved that the core regions have both uranium and zirconium and establish that carbon and nitrogen are retained during the fabrication process. Powder x-ray diffraction analysis clarifies that the light elements did not form compounds with the uranium matrix but rather incorporated into the core region forming a sub-stoichiometric UZrCN. Heat treatment performed on equimolar U-Zr-C resulted in an increase in the homogenous phase present with a diffraction pattern reflecting a ternary UZrCN despite small amounts of segregation in the final button.","abstract_has_math":false,"creators":["Sanches, David Miguel"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Nuclear Engineering","degree_department":"Mechanical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Haghighat, Alireza","Hamilton, Sarah"],"committee_members":["Freeman, David Wayne"],"year":2025,"date_issued":"2025-12-22","date_published":"2025-12-22","updated_at":"2026-07-22T22:19:03Z","subjects":["uranium-zirconium carbonitride","space nuclear propulsion","nuclear thermal rocket","high temperature ceramic fuel","arc melting"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45412"],"render_values":[{"text":"vt_gsexam:45412","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/140546","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Haghighat, Alireza","Hamilton, Sarah"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Freeman, David Wayne"]},{"key":"dc:contributor.department","label":"Department","values":["Mechanical Engineering"]},{"key":"dc:creator","label":"Author","values":["Sanches, David Miguel"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-12-23T09:00:55Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-12-23T09:00:55Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-12-22"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["uranium-zirconium carbonitride","space nuclear propulsion","nuclear thermal rocket","high temperature ceramic fuel","arc melting"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45412"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/140546"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["UZrCN has exhibited thermophysical properties beneficial to high temperature reactor applications such as nuclear thermal rockets. The present work investigates a novel liquid phase synthesis method involving the admission of nitrogen gas during arc melting of uranium, zirconium, and carbon. Initial microstructural examinations using scanning electron microscopy indicated that the samples remain heterogenous with zirconium-rich cores in a uranium-rich matrix. Heterogeneity resulted from large differences in melting temperature of the major constituents and rapid solidification. Additional energy dispersive x-ray spectroscopy, combustion analysis, and inert gas fusion analysis proved that the core regions have both uranium and zirconium and establish that carbon and nitrogen are retained during the fabrication process. Powder x-ray diffraction analysis clarifies that the light elements did not form compounds with the uranium matrix but rather incorporated into the core region forming a sub-stoichiometric UZrCN. Heat treatment performed on equimolar U-Zr-C resulted in an increase in the homogenous phase present with a diffraction pattern reflecting a ternary UZrCN despite small amounts of segregation in the final button."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Ceramic nuclear fuels of various kinds have long been the subject of rigorous study since the birth of nuclear reactor studies in the middle of the 20th century. Throughout this long history of ceramic fuel research there have been advances in high temperature ceramic fuel systems that show great promise, one of which is the uranium-zirconium carbonitride fuel system (UZrCN). UZrCN has previously been identified as a candidate fuel system for applications in space nuclear propulsion and high temperature gas reactors owing to a very high melting temperature and good thermal conductivity. This research focuses on direct casting, using a high temperature plasma arc, to fabricate the fuel system in a liquid phase as opposed to the time and energy intensive carbothermic reduction process. Using materials characterization techniques including electron microscopy, analytical chemistry, and x-ray diffraction analysis, the current research establishes the capability to fabricate this fuel by direct casting. However the fuel is not homogeneous in the as-cast state. Additional furnace tests to investigate nitriding U-Zr-C indicated formation of the target phase and increasing homogeneity, thus identifying a future research area and avenue for material fabrication."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Novel Synthesis and Characterization of Uranium-Zirconium Carbonitride by Direct Casting"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Haghighat, Alireza","Hamilton, Sarah"],"dc:contributor.committeemember":["Freeman, David Wayne"],"dc:contributor.department":["Mechanical Engineering"],"dc:creator":["Sanches, David Miguel"],"dc:date.accessioned":["2025-12-23T09:00:55Z"],"dc:date.available":["2025-12-23T09:00:55Z"],"dc:date.issued":["2025-12-22"],"dc:description.abstract":["UZrCN has exhibited thermophysical properties beneficial to high temperature reactor applications such as nuclear thermal rockets. The present work investigates a novel liquid phase synthesis method involving the admission of nitrogen gas during arc melting of uranium, zirconium, and carbon. Initial microstructural examinations using scanning electron microscopy indicated that the samples remain heterogenous with zirconium-rich cores in a uranium-rich matrix. Heterogeneity resulted from large differences in melting temperature of the major constituents and rapid solidification. Additional energy dispersive x-ray spectroscopy, combustion analysis, and inert gas fusion analysis proved that the core regions have both uranium and zirconium and establish that carbon and nitrogen are retained during the fabrication process. Powder x-ray diffraction analysis clarifies that the light elements did not form compounds with the uranium matrix but rather incorporated into the core region forming a sub-stoichiometric UZrCN. Heat treatment performed on equimolar U-Zr-C resulted in an increase in the homogenous phase present with a diffraction pattern reflecting a ternary UZrCN despite small amounts of segregation in the final button."],"dc:description.abstractgeneral":["Ceramic nuclear fuels of various kinds have long been the subject of rigorous study since the birth of nuclear reactor studies in the middle of the 20th century. Throughout this long history of ceramic fuel research there have been advances in high temperature ceramic fuel systems that show great promise, one of which is the uranium-zirconium carbonitride fuel system (UZrCN). UZrCN has previously been identified as a candidate fuel system for applications in space nuclear propulsion and high temperature gas reactors owing to a very high melting temperature and good thermal conductivity. This research focuses on direct casting, using a high temperature plasma arc, to fabricate the fuel system in a liquid phase as opposed to the time and energy intensive carbothermic reduction process. Using materials characterization techniques including electron microscopy, analytical chemistry, and x-ray diffraction analysis, the current research establishes the capability to fabricate this fuel by direct casting. However the fuel is not homogeneous in the as-cast state. Additional furnace tests to investigate nitriding U-Zr-C indicated formation of the target phase and increasing homogeneity, thus identifying a future research area and avenue for material fabrication."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:45412"],"dc:identifier.uri":["https://hdl.handle.net/10919/140546"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["uranium-zirconium carbonitride","space nuclear propulsion","nuclear thermal rocket","high temperature ceramic fuel","arc melting"],"dc:title":["Novel Synthesis and Characterization of Uranium-Zirconium Carbonitride by Direct Casting"],"dc:type":["Thesis"],"thesis:degree_discipline":["Nuclear Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:03Z"}