\"This research focuses on the oxidation behavior of silicon carbide and matrix grade graphite, specifically as it pertains to accident scenarios in Gen IV thermal spectrum high temperature gas cooled nuclear reactors. It is imperative to understand the oxidation behavior of such materials to predict their response to off-normal environments and certify their accident tolerance to implement Gen IV reactors. The onset of oxidation temperature of matrix graphite was found to have a strong dependence on the microstructure, and therefore processing parameters, of the materials. The A3-3 type grade contained regions of partially graphitized carbon that were more disordered and oxidized more readily than the A3-27 type that contained a more graphitic structure. The oxidation behavior of the SiC layer of tristructural isotropic (TRISO) fuel particles demonstrated different oxidation behavior than that of typical flat-plate chemical vapor deposited SiC and that of SiC fibers with regards to stress relief and devitrification in the SiO2 scale. By comparing the oxide layer thickness of TRISO particles oxidized in atmospheres containing 0.2 and 20 kPa O2, it was found that the mechanism responsible for oxide growth was different at each pO2, with activation energies of 168 and 230 kJ/mol, respectively. The oxide growth mechanism was consistent from 6 – 20 kPa O2, with a pO2 dependence of 0.83. TRISO particles oxidized in 0.2 kPa O2 exhibited raised nodules on the surface that were correlated with pockets of nanocrystalline SiC. The nodules were formed via the enhanced production of gaseous CO(g) and SiO(g) within grain boundaries. In regions of nanocrystalline SiC containing a high density of grain boundaries, SiO(g) within bubbles that formed along interfaces oxidized to redeposit SiO2\"--Abstract, p. iv
","abstract_html":"<p>"This research focuses on the oxidation behavior of silicon carbide and matrix grade graphite, specifically as it pertains to accident scenarios in Gen IV thermal spectrum high temperature gas cooled nuclear reactors. It is imperative to understand the oxidation behavior of such materials to predict their response to off-normal environments and certify their accident tolerance to implement Gen IV reactors. The onset of oxidation temperature of matrix graphite was found to have a strong dependence on the microstructure, and therefore processing parameters, of the materials. The A3-3 type grade contained regions of partially graphitized carbon that were more disordered and oxidized more readily than the A3-27 type that contained a more graphitic structure. The oxidation behavior of the SiC layer of tristructural isotropic (TRISO) fuel particles demonstrated different oxidation behavior than that of typical flat-plate chemical vapor deposited SiC and that of SiC fibers with regards to stress relief and devitrification in the SiO<sub>2</sub> scale. By comparing the oxide layer thickness of TRISO particles oxidized in atmospheres containing 0.2 and 20 kPa O<sub>2</sub>, it was found that the mechanism responsible for oxide growth was different at each pO<sub>2</sub>, with activation energies of 168 and 230 kJ/mol, respectively. The oxide growth mechanism was consistent from 6 – 20 kPa O<sub>2</sub>, with a pO<sub>2</sub> dependence of 0.83. TRISO particles oxidized in 0.2 kPa O<sub>2</sub> exhibited raised nodules on the surface that were correlated with pockets of nanocrystalline SiC. The nodules were formed via the enhanced production of gaseous CO(g) and SiO(g) within grain boundaries. In regions of nanocrystalline SiC containing a high density of grain boundaries, SiO(g) within bubbles that formed along interfaces oxidized to redeposit SiO<sub>2</sub>"--Abstract, p. iv</p>","abstract_has_math":false,"creators":["Bratten, Adam Thomas"],"institution":"Missouri University of Science and Technology","degree_name":"Ph. D. in Materials Science and Engineering","degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T03:18:18Z","subjects":["Materials Science and Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsmine.mst.edu/doctoral_dissertations/3216","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Bratten, Adam Thomas"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["Dissertation - Open Access"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. D. in Materials Science and 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":["Materials Science and Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsmine.mst.edu/doctoral_dissertations/3216"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["\"This research focuses on the oxidation behavior of silicon carbide and matrix grade graphite, specifically as it pertains to accident scenarios in Gen IV thermal spectrum high temperature gas cooled nuclear reactors. It is imperative to understand the oxidation behavior of such materials to predict their response to off-normal environments and certify their accident tolerance to implement Gen IV reactors. The onset of oxidation temperature of matrix graphite was found to have a strong dependence on the microstructure, and therefore processing parameters, of the materials. The A3-3 type grade contained regions of partially graphitized carbon that were more disordered and oxidized more readily than the A3-27 type that contained a more graphitic structure. The oxidation behavior of the SiC layer of tristructural isotropic (TRISO) fuel particles demonstrated different oxidation behavior than that of typical flat-plate chemical vapor deposited SiC and that of SiC fibers with regards to stress relief and devitrification in the SiO2 scale. By comparing the oxide layer thickness of TRISO particles oxidized in atmospheres containing 0.2 and 20 kPa O2, it was found that the mechanism responsible for oxide growth was different at each pO2, with activation energies of 168 and 230 kJ/mol, respectively. The oxide growth mechanism was consistent from 6 – 20 kPa O2, with a pO2 dependence of 0.83. TRISO particles oxidized in 0.2 kPa O2 exhibited raised nodules on the surface that were correlated with pockets of nanocrystalline SiC. The nodules were formed via the enhanced production of gaseous CO(g) and SiO(g) within grain boundaries. In regions of nanocrystalline SiC containing a high density of grain boundaries, SiO(g) within bubbles that formed along interfaces oxidized to redeposit SiO2\"--Abstract, p. iv
"]},{"key":"dc:title","label":"Title","values":["OXIDATION OF SILICON CARBIDE AND GRAPHITE FOR HIGH TEMPERATURE GAS-COOLED REACTOR APPLICATIONS"]}]}],"canonical_facts":{"dc:creator":["Bratten, Adam Thomas"],"dc:description.abstract":["\"This research focuses on the oxidation behavior of silicon carbide and matrix grade graphite, specifically as it pertains to accident scenarios in Gen IV thermal spectrum high temperature gas cooled nuclear reactors. It is imperative to understand the oxidation behavior of such materials to predict their response to off-normal environments and certify their accident tolerance to implement Gen IV reactors. The onset of oxidation temperature of matrix graphite was found to have a strong dependence on the microstructure, and therefore processing parameters, of the materials. The A3-3 type grade contained regions of partially graphitized carbon that were more disordered and oxidized more readily than the A3-27 type that contained a more graphitic structure. The oxidation behavior of the SiC layer of tristructural isotropic (TRISO) fuel particles demonstrated different oxidation behavior than that of typical flat-plate chemical vapor deposited SiC and that of SiC fibers with regards to stress relief and devitrification in the SiO2 scale. By comparing the oxide layer thickness of TRISO particles oxidized in atmospheres containing 0.2 and 20 kPa O2, it was found that the mechanism responsible for oxide growth was different at each pO2, with activation energies of 168 and 230 kJ/mol, respectively. The oxide growth mechanism was consistent from 6 – 20 kPa O2, with a pO2 dependence of 0.83. TRISO particles oxidized in 0.2 kPa O2 exhibited raised nodules on the surface that were correlated with pockets of nanocrystalline SiC. The nodules were formed via the enhanced production of gaseous CO(g) and SiO(g) within grain boundaries. In regions of nanocrystalline SiC containing a high density of grain boundaries, SiO(g) within bubbles that formed along interfaces oxidized to redeposit SiO2\"--Abstract, p. iv
"],"dc:identifier":["https://scholarsmine.mst.edu/doctoral_dissertations/3216"],"dc:subject":["Materials Science and Engineering"],"dc:title":["OXIDATION OF SILICON CARBIDE AND GRAPHITE FOR HIGH TEMPERATURE GAS-COOLED REACTOR APPLICATIONS"],"dc:type":["Dissertation - Open Access"],"thesis:degree_name":["Ph. D. in Materials Science and Engineering"],"thesis:institution_name":["Missouri University of Science and Technology"]},"updated_at":"2026-07-24T03:18:18Z"}