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Use of Organic Bases in the Synthesis of Geopolymers
Use of Organic Bases in the Synthesis of Geopolymers
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202105703
- ISBN
- 9798263308087
- DDC
- 620.11
- 저자명
- Samuel, Devon.
- 서명/저자
- Use of Organic Bases in the Synthesis of Geopolymers
- 발행사항
- [Sl] : University of Illinois at Urbana-Champaign, 2024
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2024
- 형태사항
- 241 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 87-05, Section: B.
- 주기사항
- Advisor: Kriven, Waltraud M.
- 학위논문주기
- Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2024.
- 초록/해제
- 요약Alkali geopolymers are a facile forming route for alkali aluminosilicate ceramics because they are formed as fluids and crystallize upon heating to about 1000 °C. It is also possible to replace the alkali cations by an ion exchange process, expanding the number of ceramic compositions that can be made while taking advantage of the versatility in forming afforded by geopolymers. However, the ion exchange process is very slow for small bodies and entirely impractical for pieces thicker than a few millimeters. This thesis investigated the synthesis of geopolymers with organic bases rather than inorganic alkali hydroxides. This would avoid the use of alkali cations entirely and greatly widen the range of ceramics formable via geopolymers. Three organic bases were tested - guanidine, 1,1,3,3-tetramethylguanidine (TMG), and tetramethylammonium hydroxide (TMAOH) - for their ability to form geopolymers with Al2O3:SiO2 ratios of 1:2 and 1:4 as well as 3:2 to match the composition of mullite, a common ceramic. Guanidine was successful, causing reaction at room temperature and producing bodies with atomic structures and microstructures similar to the equivalent sodium geopolymer compositions. TMAOH was able to induce setting in Al2O3•4 SiO2 systems, but they required heating to 50 °C for 1 month, and the resultant bodies were substantially different from sodium geopolymers. An even higher cure temperature, such as 80 °C, might reduce the setting time and improve the reaction into a geopolymeric material. TMG was entirely unsuccessful, and no compositions solidified or even exhibited a substantial extent of reaction. For the organic base compositions that solidified, their crystallization upon heating was studied up to 1600 °C. The Al2O3•2 SiO2 and Al2O3•4 SiO2 compositions produced mullite + glass and the 3 Al2O3•2 SiO2 compositions became almost pure mullite. All of them had substantial amounts of porosity after firing from a combination of the geopolymer synthesis method and the firing program. The amount of porosity and crystal morphology varied with the organic base, overall composition, and choice of precursors used to reach the 3 Al2O3•2 SiO2 composition. An alternative route to casting a pre-mullite material was devised which relied only on having a solution with high pH and an amorphous mullite powder with a high fraction of five-coordinated aluminum. These compositions behaved like hydratable alumina binders and were bound together by precipitated aluminum hydroxide phases rather than geopolymer. However, it seemed to be more generally viable and all of the organic bases, including TMG, caused setting in a short time, albeit with some differences in the microstructure and density after firing. Attempts to extend this method to non-mullite aluminate compositions, using MgO•Al2O3 and 3 Y2O3•5 Al2O3 as examples, were not successful. Although the use of an alkaline solution instead of water alone did induce a greater degree of aluminum hydroxide precipitation, there was not always enough aluminum hydroxide to bind the material and setting was sometimes delayed rather than accelerated. The use of organic base geopolymers for producing non-mullite ceramics was demonstrated by the synthesis of cordierite (2 MgO•2 Al2O3•5 SiO2) from a guanidine metakaolin-based geopolymer. The field of available ceramics was expanded further by showing that geopolymer-like materials could be made using Y2O3 and ZnO as substitutes for metakaolin, giving Y2O3•2 SiO2 and 2 ZnO•SiO2 compositions, respectively.
- 일반주제명
- Materials science
- 일반주제명
- Engineering
- 키워드
- Geopolymers
- 키워드
- Organic base
- 기타저자
- University of Illinois at Urbana-Champaign Materials Science & Engineerng
- 기본자료저록
- Dissertations Abstracts International. 87-05B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■020 ▼a9798263308087
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■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a620.11
■1001 ▼aSamuel, Devon.
■24510▼aUse of Organic Bases in the Synthesis of Geopolymers
■260 ▼a[Sl]▼bUniversity of Illinois at Urbana-Champaign▼c2024
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2024
■300 ▼a241 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 87-05, Section: B.
■500 ▼aAdvisor: Kriven, Waltraud M.
■5021 ▼aThesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2024.
■520 ▼aAlkali geopolymers are a facile forming route for alkali aluminosilicate ceramics because they are formed as fluids and crystallize upon heating to about 1000 °C. It is also possible to replace the alkali cations by an ion exchange process, expanding the number of ceramic compositions that can be made while taking advantage of the versatility in forming afforded by geopolymers. However, the ion exchange process is very slow for small bodies and entirely impractical for pieces thicker than a few millimeters. This thesis investigated the synthesis of geopolymers with organic bases rather than inorganic alkali hydroxides. This would avoid the use of alkali cations entirely and greatly widen the range of ceramics formable via geopolymers. Three organic bases were tested - guanidine, 1,1,3,3-tetramethylguanidine (TMG), and tetramethylammonium hydroxide (TMAOH) - for their ability to form geopolymers with Al2O3:SiO2 ratios of 1:2 and 1:4 as well as 3:2 to match the composition of mullite, a common ceramic. Guanidine was successful, causing reaction at room temperature and producing bodies with atomic structures and microstructures similar to the equivalent sodium geopolymer compositions. TMAOH was able to induce setting in Al2O3•4 SiO2 systems, but they required heating to 50 °C for 1 month, and the resultant bodies were substantially different from sodium geopolymers. An even higher cure temperature, such as 80 °C, might reduce the setting time and improve the reaction into a geopolymeric material. TMG was entirely unsuccessful, and no compositions solidified or even exhibited a substantial extent of reaction. For the organic base compositions that solidified, their crystallization upon heating was studied up to 1600 °C. The Al2O3•2 SiO2 and Al2O3•4 SiO2 compositions produced mullite + glass and the 3 Al2O3•2 SiO2 compositions became almost pure mullite. All of them had substantial amounts of porosity after firing from a combination of the geopolymer synthesis method and the firing program. The amount of porosity and crystal morphology varied with the organic base, overall composition, and choice of precursors used to reach the 3 Al2O3•2 SiO2 composition. An alternative route to casting a pre-mullite material was devised which relied only on having a solution with high pH and an amorphous mullite powder with a high fraction of five-coordinated aluminum. These compositions behaved like hydratable alumina binders and were bound together by precipitated aluminum hydroxide phases rather than geopolymer. However, it seemed to be more generally viable and all of the organic bases, including TMG, caused setting in a short time, albeit with some differences in the microstructure and density after firing. Attempts to extend this method to non-mullite aluminate compositions, using MgO•Al2O3 and 3 Y2O3•5 Al2O3 as examples, were not successful. Although the use of an alkaline solution instead of water alone did induce a greater degree of aluminum hydroxide precipitation, there was not always enough aluminum hydroxide to bind the material and setting was sometimes delayed rather than accelerated. The use of organic base geopolymers for producing non-mullite ceramics was demonstrated by the synthesis of cordierite (2 MgO•2 Al2O3•5 SiO2) from a guanidine metakaolin-based geopolymer. The field of available ceramics was expanded further by showing that geopolymer-like materials could be made using Y2O3 and ZnO as substitutes for metakaolin, giving Y2O3•2 SiO2 and 2 ZnO•SiO2 compositions, respectively.
■590 ▼aSchool code: 0090.
■650 4▼aMaterials science
■650 4▼aEngineering
■653 ▼aGeopolymers
■653 ▼aOrganic base
■653 ▼aAluminosilicate ceramics
■690 ▼a0794
■690 ▼a0537
■71020▼aUniversity of Illinois at Urbana-Champaign▼bMaterials Science & Engineerng.
■7730 ▼tDissertations Abstracts International▼g87-05B.
■790 ▼a0090
■791 ▼aPh.D.
■792 ▼a2024
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17361085▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
