{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/43063"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/43063","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Thermal expansion of chemically modified mullite","abstract":"Solid-state reaction and sol-gel, processing techniques were used extensively to form chemically-modified mullite solid solutions in an effort to lower their thermal expansion coefficients. TiO₂, B₂O₃, CrPO₄, P2O₅, Ga₂O₃, Cr2O₃, and WO₃ and the half-breed SiO₂ compounds AlPas, BPO₄, GaPO₄, BAsO₄, AIAsO₄, GaAsO₄, and GeO₂ were chosen as the modifiers. The results indicate that, apart from TiO₂, none of the substitutions made in mullite significantly change the thermal expansion properties. The solubility of 3 wt% TiO₂ in mullite reduces the coefficient of thermal expansion by about 10%; That corresponds to a reduction in AAl₂O₃/SiO₂ molar ratio ( < 1.5) compared to stoichiometric mullite (3Al₂O₃·2SiO₂). The formation of TiO₂-modified mullite depends on processing condition and heat treatment. The possible mechanism of lowering the CTE of mullite by the addition of TiO₂ is discussed in terms of the bond strength. The axial expansion of a Ga2O₃-modified mullite was measured' up to 1200°C to show that the expansion is increased along the c-axis compared with that of the stoichiometric mullite.","abstract_html":"Solid-state reaction and sol-gel, processing techniques were used extensively to form chemically-modified mullite solid solutions in an effort to lower their thermal expansion coefficients. TiO₂, B₂O₃, CrPO₄, P2O₅, Ga₂O₃, Cr2O₃, and WO₃ and the half-breed SiO₂ compounds AlPas, BPO₄, GaPO₄, BAsO₄, AIAsO₄, GaAsO₄, and GeO₂ were chosen as the modifiers. The results indicate that, apart from TiO₂, none of the substitutions made in mullite significantly change the thermal expansion properties. The solubility of 3 wt% TiO₂ in mullite reduces the coefficient of thermal expansion by about 10%; That corresponds to a reduction in AAl₂O₃/SiO₂ molar ratio ( &lt; 1.5) compared to stoichiometric mullite (3Al₂O₃·2SiO₂). The formation of TiO₂-modified mullite depends on processing condition and heat treatment. The possible mechanism of lowering the CTE of mullite by the addition of TiO₂ is discussed in terms of the bond strength. The axial expansion of a Ga2O₃-modified mullite was measured&#x27; up to 1200°C to show that the expansion is increased along the c-axis compared with that of the stoichiometric mullite.","abstract_has_math":false,"creators":["Tu, Jie"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Materials Engineering","degree_department":"Materials Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Brown, Jesse J. Jr."],"committee_members":["Swanson, Robert E.","Ribbe, Paul H."],"year":1988,"date_issued":"1988-05-05","date_published":"1988-05-05","updated_at":"2026-07-22T22:20:23Z","subjects":[],"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":["etd-06102012-040330"],"render_values":[{"text":"etd-06102012-040330","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/43063","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Brown, Jesse J. 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TiO₂, B₂O₃, CrPO₄, P2O₅, Ga₂O₃, Cr2O₃, and WO₃ and the half-breed SiO₂ compounds AlPas, BPO₄, GaPO₄, BAsO₄, AIAsO₄, GaAsO₄, and GeO₂ were chosen as the modifiers. The results indicate that, apart from TiO₂, none of the substitutions made in mullite significantly change the thermal expansion properties. The solubility of 3 wt% TiO₂ in mullite reduces the coefficient of thermal expansion by about 10%; That corresponds to a reduction in AAl₂O₃/SiO₂ molar ratio ( < 1.5) compared to stoichiometric mullite (3Al₂O₃·2SiO₂). The formation of TiO₂-modified mullite depends on processing condition and heat treatment. The possible mechanism of lowering the CTE of mullite by the addition of TiO₂ is discussed in terms of the bond strength. The axial expansion of a Ga2O₃-modified mullite was measured' up to 1200°C to show that the expansion is increased along the c-axis compared with that of the stoichiometric mullite."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Thermal expansion of chemically modified mullite"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Brown, Jesse J. Jr."],"dc:contributor.committeemember":["Swanson, Robert E.","Ribbe, Paul H."],"dc:contributor.department":["Materials Engineering"],"dc:creator":["Tu, Jie"],"dc:date.accessioned":["2014-03-14T21:37:42Z"],"dc:date.available":["2014-03-14T21:37:42Z","2012-06-10"],"dc:date.issued":["1988-05-05"],"dc:description.abstract":["Solid-state reaction and sol-gel, processing techniques were used extensively to form chemically-modified mullite solid solutions in an effort to lower their thermal expansion coefficients. TiO₂, B₂O₃, CrPO₄, P2O₅, Ga₂O₃, Cr2O₃, and WO₃ and the half-breed SiO₂ compounds AlPas, BPO₄, GaPO₄, BAsO₄, AIAsO₄, GaAsO₄, and GeO₂ were chosen as the modifiers. The results indicate that, apart from TiO₂, none of the substitutions made in mullite significantly change the thermal expansion properties. The solubility of 3 wt% TiO₂ in mullite reduces the coefficient of thermal expansion by about 10%; That corresponds to a reduction in AAl₂O₃/SiO₂ molar ratio ( < 1.5) compared to stoichiometric mullite (3Al₂O₃·2SiO₂). The formation of TiO₂-modified mullite depends on processing condition and heat treatment. The possible mechanism of lowering the CTE of mullite by the addition of TiO₂ is discussed in terms of the bond strength. The axial expansion of a Ga2O₃-modified mullite was measured' up to 1200°C to show that the expansion is increased along the c-axis compared with that of the stoichiometric mullite."],"dc:description.degree":["Master of Science"],"dc:format.medium":["BTD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-06102012-040330"],"dc:identifier.uri":["http://hdl.handle.net/10919/43063"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Thermal expansion of chemically modified mullite"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Materials Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:23Z"}