{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/95522"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/95522","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Synthesis and indentation of boride and carbide coated carbon nanotube composite microstructures","abstract":"The goal of this thesis is to investigate the synthesis and mechanical behavior of novel refractory coatings for applications subjected to extreme conditions. Starting from aligned carbon nanotube (CNT) forests as scaffolds, composite foams are fabricated by infiltration with refractory materials to achieve desirable mechanical properties such as high stiffness and strength. Similar to naturally occurring materials such as bone and teeth, these properties are dictated by the composition and nanoarchitecture of the material structure. CNTs grown into vertically aligned pillars by chemical vapor deposition (CVD) mimic the microstructure of these natural foams through their porous nanostructure. The CNT pillars are then coated using two methods: (i) static CVD with a hafnium diboride precursor (Hf[BH4]4) leading to coating thicknesses ranging from 3nm to 50 nm; and (ii) through cycles of elasto-capillary imbibition and pyrolysis of a silicon oxycarbide (SiOC) polymer derived ceramic leading to coating thickness from 8 nm to full infiltration. Both coatings enable the infiltration of CNT pillars and lead to a significant increase in stiffness and strength. Nanoindentation tests using a flat punch were performed on the CNT pillars to measure their Young’s modulus and compressive strength. By varying the CNT coating thickness, a trend develops for the Young’s modulus as a function of coating thickness for the CNT pillars where E ~ ρ^1.698 for hafnium diboride coated pillars. The maximum stiffness and strength was 56.49 GPa and 1.94 GPa for the fully infiltrated HfB2 composite and 3.80 GPa and 13.87 MPa for the SiOC pillars. We also identify the different regimes of deformation for the pillars to better understand the coating processes and the material behavior. These results can enable new applications of CNTs in extreme environments where high temperature resistance and high mechanical resilience are needed, such as hypersonic vehicles.","abstract_html":"The goal of this thesis is to investigate the synthesis and mechanical behavior of novel refractory coatings for applications subjected to extreme conditions. Starting from aligned carbon nanotube (CNT) forests as scaffolds, composite foams are fabricated by infiltration with refractory materials to achieve desirable mechanical properties such as high stiffness and strength. Similar to naturally occurring materials such as bone and teeth, these properties are dictated by the composition and nanoarchitecture of the material structure. CNTs grown into vertically aligned pillars by chemical vapor deposition (CVD) mimic the microstructure of these natural foams through their porous nanostructure. The CNT pillars are then coated using two methods: (i) static CVD with a hafnium diboride precursor (Hf[BH4]4) leading to coating thicknesses ranging from 3nm to 50 nm; and (ii) through cycles of elasto-capillary imbibition and pyrolysis of a silicon oxycarbide (SiOC) polymer derived ceramic leading to coating thickness from 8 nm to full infiltration. Both coatings enable the infiltration of CNT pillars and lead to a significant increase in stiffness and strength. Nanoindentation tests using a flat punch were performed on the CNT pillars to measure their Young’s modulus and compressive strength. By varying the CNT coating thickness, a trend develops for the Young’s modulus as a function of coating thickness for the CNT pillars where E ~ ρ^1.698 for hafnium diboride coated pillars. The maximum stiffness and strength was 56.49 GPa and 1.94 GPa for the fully infiltrated HfB2 composite and 3.80 GPa and 13.87 MPa for the SiOC pillars. We also identify the different regimes of deformation for the pillars to better understand the coating processes and the material behavior. These results can enable new applications of CNTs in extreme environments where high temperature resistance and high mechanical resilience are needed, such as hypersonic vehicles.","abstract_has_math":false,"creators":["Sandin, Carly Renee"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Tawfick, Sameh"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-03-01T16:37:12Z","date_published":"2017-03-01T16:37:12Z","updated_at":"2026-07-22T22:26:37Z","subjects":["carbon nanotubes","carbon nanotube composites","hafnium diboride","polymer derived ceramics","nanoindentation"],"languages":["en"],"rights":["© 2016 Carly Renee Sandin"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/95522","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Tawfick, Sameh"]},{"key":"dc:creator","label":"Author","values":["Sandin, Carly Renee"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2017-03-01T16:37:12Z","2019-03-02T10:15:24Z","2016-12-09","2016-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["carbon nanotubes","carbon nanotube composites","hafnium diboride","polymer derived ceramics","nanoindentation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["© 2016 Carly Renee Sandin"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/95522"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The goal of this thesis is to investigate the synthesis and mechanical behavior of novel refractory coatings for applications subjected to extreme conditions. Starting from aligned carbon nanotube (CNT) forests as scaffolds, composite foams are fabricated by infiltration with refractory materials to achieve desirable mechanical properties such as high stiffness and strength. Similar to naturally occurring materials such as bone and teeth, these properties are dictated by the composition and nanoarchitecture of the material structure. CNTs grown into vertically aligned pillars by chemical vapor deposition (CVD) mimic the microstructure of these natural foams through their porous nanostructure. The CNT pillars are then coated using two methods: (i) static CVD with a hafnium diboride precursor (Hf[BH4]4) leading to coating thicknesses ranging from 3nm to 50 nm; and (ii) through cycles of elasto-capillary imbibition and pyrolysis of a silicon oxycarbide (SiOC) polymer derived ceramic leading to coating thickness from 8 nm to full infiltration. Both coatings enable the infiltration of CNT pillars and lead to a significant increase in stiffness and strength. Nanoindentation tests using a flat punch were performed on the CNT pillars to measure their Young’s modulus and compressive strength. By varying the CNT coating thickness, a trend develops for the Young’s modulus as a function of coating thickness for the CNT pillars where E ~ ρ^1.698 for hafnium diboride coated pillars. The maximum stiffness and strength was 56.49 GPa and 1.94 GPa for the fully infiltrated HfB2 composite and 3.80 GPa and 13.87 MPa for the SiOC pillars. We also identify the different regimes of deformation for the pillars to better understand the coating processes and the material behavior. These results can enable new applications of CNTs in extreme environments where high temperature resistance and high mechanical resilience are needed, such as hypersonic vehicles.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-12-01","The student, Carly Sandin, accepted the attached license on 2016-12-09 at 11:42.","The student, Carly Sandin, submitted this Thesis for approval on 2016-12-09 at 11:52.","This Thesis was approved for publication on 2016-12-09 at 13:57.","DSpace SAF Submission Ingestion Package generated from Vireo submission #10507 on 2017-02-28 at 14:37:41","Made available in DSpace on 2017-03-01T16:37:12Z (GMT). No. of bitstreams: 2 SANDIN-THESIS-2016.pdf: 6974607 bytes, checksum: 97846c350742d909a5419e3920cd4726 (MD5) LICENSE.txt: 4209 bytes, checksum: 6537e1010010f774c8968fc565ee6644 (MD5) Previous issue date: 2016-12-09","Embargo set by: Seth Robbins for item 98638 Lift date: 2019-03-01T16:37:19Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 98638 on 2019-03-02T10:15:24Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Synthesis and indentation of boride and carbide coated carbon nanotube composite microstructures"]}]}],"canonical_facts":{"dc:contributor":["Tawfick, Sameh"],"dc:creator":["Sandin, Carly Renee"],"dc:date":["2017-03-01T16:37:12Z","2019-03-02T10:15:24Z","2016-12-09","2016-12"],"dc:description":["The goal of this thesis is to investigate the synthesis and mechanical behavior of novel refractory coatings for applications subjected to extreme conditions. Starting from aligned carbon nanotube (CNT) forests as scaffolds, composite foams are fabricated by infiltration with refractory materials to achieve desirable mechanical properties such as high stiffness and strength. Similar to naturally occurring materials such as bone and teeth, these properties are dictated by the composition and nanoarchitecture of the material structure. CNTs grown into vertically aligned pillars by chemical vapor deposition (CVD) mimic the microstructure of these natural foams through their porous nanostructure. The CNT pillars are then coated using two methods: (i) static CVD with a hafnium diboride precursor (Hf[BH4]4) leading to coating thicknesses ranging from 3nm to 50 nm; and (ii) through cycles of elasto-capillary imbibition and pyrolysis of a silicon oxycarbide (SiOC) polymer derived ceramic leading to coating thickness from 8 nm to full infiltration. Both coatings enable the infiltration of CNT pillars and lead to a significant increase in stiffness and strength. Nanoindentation tests using a flat punch were performed on the CNT pillars to measure their Young’s modulus and compressive strength. By varying the CNT coating thickness, a trend develops for the Young’s modulus as a function of coating thickness for the CNT pillars where E ~ ρ^1.698 for hafnium diboride coated pillars. The maximum stiffness and strength was 56.49 GPa and 1.94 GPa for the fully infiltrated HfB2 composite and 3.80 GPa and 13.87 MPa for the SiOC pillars. We also identify the different regimes of deformation for the pillars to better understand the coating processes and the material behavior. These results can enable new applications of CNTs in extreme environments where high temperature resistance and high mechanical resilience are needed, such as hypersonic vehicles.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-12-01","The student, Carly Sandin, accepted the attached license on 2016-12-09 at 11:42.","The student, Carly Sandin, submitted this Thesis for approval on 2016-12-09 at 11:52.","This Thesis was approved for publication on 2016-12-09 at 13:57.","DSpace SAF Submission Ingestion Package generated from Vireo submission #10507 on 2017-02-28 at 14:37:41","Made available in DSpace on 2017-03-01T16:37:12Z (GMT). No. of bitstreams: 2 SANDIN-THESIS-2016.pdf: 6974607 bytes, checksum: 97846c350742d909a5419e3920cd4726 (MD5) LICENSE.txt: 4209 bytes, checksum: 6537e1010010f774c8968fc565ee6644 (MD5) Previous issue date: 2016-12-09","Embargo set by: Seth Robbins for item 98638 Lift date: 2019-03-01T16:37:19Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 98638 on 2019-03-02T10:15:24Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/95522"],"dc:language":["en"],"dc:rights":["© 2016 Carly Renee Sandin"],"dc:subject":["carbon nanotubes","carbon nanotube composites","hafnium diboride","polymer derived ceramics","nanoindentation"],"dc:title":["Synthesis and indentation of boride and carbide coated carbon nanotube composite microstructures"],"dc:type":["text"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:37Z"}