\"The research presented in this dissertation is focused on the thermal conductivity (k) of ZrB2 ceramics. The goal was to develop a better understanding of how various solid solutions and second phases affect the thermal and electrical transport in ZrB2, 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 addition of ZrH2. This allowed the ZrB2-C binary system to be evaluated for study two. Study two showed the k of ZrB2 is reduced by C in solid solution and as a second phase due to the decrease in the electron contribution to thermal conductivity. Conductivities of 99 (25⁰C) and 76 W/m·K (2000⁰C) were obtained for the most pure ZrB2 (0.026 wt% C in solution and 0.2 vol% zirconia) produced in this study, which are the highest reported values for ZrB2 processed using commercial powders since 1980.
The third study evaluated the electrical resistivity of ZrB2 up to 1860⁰C using the van der Pauw technique. Separate linear regimes were observed below and above 950⁰C, whereas, previous studies assumed a linear relation. Finally the effect of ZrC on the (Zr,W)B2 solid solution was evaluated in study four. The formation of (Zr,W)C initially increased k, but further ZrC additions resulted in decreased thermal conductivities.
In the end, this research provides both: (1) usable information for the design of future ultra-high temperature ceramic systems; and (2) fundamental research that lays the groundwork for future studies aimed at understanding thermal transport in diboride based materials\"--Abstract, page iv.
","abstract_html":"<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 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 addition of ZrH<sub>2</sub>. This allowed the ZrB<sub>2</sub>-C binary system to be evaluated for study two. Study two showed the k of ZrB<sub>2</sub> is reduced by C in solid solution and as a second phase due to the decrease in the electron contribution to thermal conductivity. Conductivities of 99 (25⁰C) and 76 W/m·K (2000⁰C) were obtained for the most pure ZrB<sub>2</sub> (0.026 wt% C in solution and 0.2 vol% zirconia) produced in this study, which are the highest reported values for ZrB<sub>2</sub> processed using commercial powders since 1980.</p> <p>The third study evaluated the electrical resistivity of ZrB<sub>2</sub> up to 1860⁰C using the van der Pauw technique. Separate linear regimes were observed below and above 950⁰C, whereas, previous studies assumed a linear relation. Finally the effect of ZrC on the (Zr,W)B<sub>2</sub> solid solution was evaluated in study four. The formation of (Zr,W)C initially increased k, but further ZrC additions resulted in decreased thermal conductivities.</p> <p>In the end, this research provides both: (1) usable information for the design of future ultra-high temperature ceramic systems; and (2) fundamental research that lays the groundwork for future studies aimed at understanding thermal transport in diboride based materials"--Abstract, page iv.</p>","abstract_has_math":false,"creators":["Harrington, Gregory John Kenneth"],"institution":"Missouri University of Science and Technology","degree_name":"Ph. D. in Ceramic Engineering","degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-02-10T08:00:00Z","date_published":"2016-02-10T08:00:00Z","updated_at":"2026-07-24T03:19:54Z","subjects":["Electrical conductivity","Lorenz number","Thermal conductivity","Ultra-high temperature ceramics","ZrB2","Ceramic Materials"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsmine.mst.edu/doctoral_dissertations/2343","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Harrington, Gregory John Kenneth"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-02-10T08:00:00Z"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation - Open Access"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. D. in Ceramic Engineering"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Missouri University of Science and Technology"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Electrical conductivity","Lorenz number","Thermal conductivity","Ultra-high temperature ceramics","ZrB2","Ceramic Materials"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsmine.mst.edu/doctoral_dissertations/2343"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["\"The research presented in this dissertation is focused on the thermal conductivity (k) of ZrB2 ceramics. The goal was to develop a better understanding of how various solid solutions and second phases affect the thermal and electrical transport in ZrB2, 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 addition of ZrH2. This allowed the ZrB2-C binary system to be evaluated for study two. Study two showed the k of ZrB2 is reduced by C in solid solution and as a second phase due to the decrease in the electron contribution to thermal conductivity. Conductivities of 99 (25⁰C) and 76 W/m·K (2000⁰C) were obtained for the most pure ZrB2 (0.026 wt% C in solution and 0.2 vol% zirconia) produced in this study, which are the highest reported values for ZrB2 processed using commercial powders since 1980.
The third study evaluated the electrical resistivity of ZrB2 up to 1860⁰C using the van der Pauw technique. Separate linear regimes were observed below and above 950⁰C, whereas, previous studies assumed a linear relation. Finally the effect of ZrC on the (Zr,W)B2 solid solution was evaluated in study four. The formation of (Zr,W)C initially increased k, but further ZrC additions resulted in decreased thermal conductivities.
In the end, this research provides both: (1) usable information for the design of future ultra-high temperature ceramic systems; and (2) fundamental research that lays the groundwork for future studies aimed at understanding thermal transport in diboride based materials\"--Abstract, page iv.
"]},{"key":"dc:title","label":"Title","values":["Effect of solid solutions and second phases on the thermal conductivity of zirconium diboride ceramics"]}]}],"canonical_facts":{"dc:creator":["Harrington, Gregory John Kenneth"],"dc:date.available":["2016-02-10T08:00:00Z"],"dc:description.abstract":["\"The research presented in this dissertation is focused on the thermal conductivity (k) of ZrB2 ceramics. The goal was to develop a better understanding of how various solid solutions and second phases affect the thermal and electrical transport in ZrB2, 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 addition of ZrH2. This allowed the ZrB2-C binary system to be evaluated for study two. Study two showed the k of ZrB2 is reduced by C in solid solution and as a second phase due to the decrease in the electron contribution to thermal conductivity. Conductivities of 99 (25⁰C) and 76 W/m·K (2000⁰C) were obtained for the most pure ZrB2 (0.026 wt% C in solution and 0.2 vol% zirconia) produced in this study, which are the highest reported values for ZrB2 processed using commercial powders since 1980.
The third study evaluated the electrical resistivity of ZrB2 up to 1860⁰C using the van der Pauw technique. Separate linear regimes were observed below and above 950⁰C, whereas, previous studies assumed a linear relation. Finally the effect of ZrC on the (Zr,W)B2 solid solution was evaluated in study four. The formation of (Zr,W)C initially increased k, but further ZrC additions resulted in decreased thermal conductivities.
In the end, this research provides both: (1) usable information for the design of future ultra-high temperature ceramic systems; and (2) fundamental research that lays the groundwork for future studies aimed at understanding thermal transport in diboride based materials\"--Abstract, page iv.
"],"dc:identifier":["https://scholarsmine.mst.edu/doctoral_dissertations/2343"],"dc:subject":["Electrical conductivity","Lorenz number","Thermal conductivity","Ultra-high temperature ceramics","ZrB2","Ceramic Materials"],"dc:title":["Effect of solid solutions and second phases on the thermal conductivity of zirconium diboride ceramics"],"dc:type":["Dissertation - Open Access"],"thesis:degree_name":["Ph. D. in Ceramic Engineering"],"thesis:institution_name":["Missouri University of Science and Technology"]},"updated_at":"2026-07-24T03:19:54Z"}