Hierarchically porous composites for CO2-capture have been produced by coating the inner walls of foam-like macroporous alumina monoliths, produced by templated synthesis, with microporous zeolite ...
{"title":"Colloidal processing and CO2-capture performance of hierarchically porous Al2O3-zeolite 13X composites","authors":"L. Andersson, F. Akhtar, Arto Ojuva, L. Bergström","doi":"10.4416/JCST2012-00039","DOIUrl":"https://doi.org/10.4416/JCST2012-00039","url":null,"abstract":"Hierarchically porous composites for CO2-capture have been produced by coating the inner walls of foam-like macroporous alumina monoliths, produced by templated synthesis, with microporous zeolite ...","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"3 1","pages":"9-16"},"PeriodicalIF":0.5,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70790190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juha‐Pekka Nikkanen, E. Huttunen-Saarivirta, T. Kanerva, V. Pore, T. Kivela, E. Lelanen, T. Mäntylä
{"title":"Photoactive TiO2 Nanopowder Synthesized at Low Temperature without a Catalyst","authors":"Juha‐Pekka Nikkanen, E. Huttunen-Saarivirta, T. Kanerva, V. Pore, T. Kivela, E. Lelanen, T. Mäntylä","doi":"10.4416/JCST2011-00008","DOIUrl":"https://doi.org/10.4416/JCST2011-00008","url":null,"abstract":"","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"2 1","pages":"97-102"},"PeriodicalIF":0.5,"publicationDate":"2011-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70790046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Highly Porous 3D Printed Stoneware Ceramic","authors":"Seattle, Wa","doi":"10.4416/JCST2011-00042","DOIUrl":"https://doi.org/10.4416/JCST2011-00042","url":null,"abstract":"","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"3 1","pages":"41-48"},"PeriodicalIF":0.5,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70790105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jakob Wilfert, K. Meier, K. Hahn, Y. Grin, Martin Jansen
Preceramic polyborocarbosilazane was pyrolysed at 900 °C and 1400 °C, respectively, yielding amorphous SiBNC. The as-obtained powders were subsequently spark plasma sintered (SPS) at temperatures in a range between 1400 °C and 1800 °C for 10 minutes under uniaxial pressure of 50 MPa. The samples have been characterized by SEM, TEM, XRD, helium pycnometry and Vickers hardness measurements. Independent of the pyrolysis temperature of the starting materials, the most compact samples were obtained by SPS at 1800 °C. In SPS conditions the onset of crystallization and phase separation of the amorphous SiBNC ceramic is substantially reduced as compared to conventional heating. A composite microstructure is obtained, which consists of SiC crystallites with diameters smaller than 500 nm, embedded in a matrix of turbostratic BN. Hardness values increase to 3 GPa when the SPS temperature is raised. TGA in O2 shows a high resistance against oxidation of the SPS compacts.
{"title":"SiC/BN Composites by Spark Plasma Sintering (SPS) of Precursor-Derived SiBNC Powders","authors":"Jakob Wilfert, K. Meier, K. Hahn, Y. Grin, Martin Jansen","doi":"10.4416/JCST2010-00012","DOIUrl":"https://doi.org/10.4416/JCST2010-00012","url":null,"abstract":"Preceramic polyborocarbosilazane was pyrolysed at 900 °C and 1400 °C, respectively, yielding amorphous SiBNC. The as-obtained powders were subsequently spark plasma sintered (SPS) at temperatures in a range between 1400 °C and 1800 °C for 10 minutes under uniaxial pressure of 50 MPa. The samples have been characterized by SEM, TEM, XRD, helium pycnometry and Vickers hardness measurements. Independent of the pyrolysis temperature of the starting materials, the most compact samples were obtained by SPS at 1800 °C. In SPS conditions the onset of crystallization and phase separation of the amorphous SiBNC ceramic is substantially reduced as compared to conventional heating. A composite microstructure is obtained, which consists of SiC crystallites with diameters smaller than 500 nm, embedded in a matrix of turbostratic BN. Hardness values increase to 3 GPa when the SPS temperature is raised. TGA in O2 shows a high resistance against oxidation of the SPS compacts.","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"1 1","pages":"1-6"},"PeriodicalIF":0.5,"publicationDate":"2010-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70789991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Riessen, W. Rickard, Ross P. Williams, G. Riessen
Alkali-activated materials (AAMs) and geopolymers have been extensively studied, although widespread commercialisation has been hampered, in part, by the use of precursors that are rarely homogeneous and are generally poorly characterised. Even when precursors are well characterised, their extent of reaction during geopolymer synthesis is not well known, leading to a disparity between targeted and actual compositional ratios. Small variations in compositional ratios, particularly Si:Al, can lead to dramatic changes in physical properties. A process for characterising precursors, focussing on their reactive component, will be described here, followed by methods that can be used to determine the extent of reaction in the final product. Characterising the final product is important, but it does not reveal what processes occur between mixing the precursors and setting of the solid geopolymer. We will also describe a method that can be used to track dissolution of precursors and subsequent evolution of the alkali-activated product, thus providing a more comprehensive picture of geopolymerisation. This paper demonstrates a link between precursor characterisation and the extent of reaction in order to provide those working with alkali-activated materials with additional knowledge enabling them to manufacture reproducible, high-quality products.
{"title":"Methods for geopolymer formulation development and microstructural analysis","authors":"A. Riessen, W. Rickard, Ross P. Williams, G. Riessen","doi":"10.4416/JCST2017-00065","DOIUrl":"https://doi.org/10.4416/JCST2017-00065","url":null,"abstract":"Alkali-activated materials (AAMs) and geopolymers have been extensively studied, although widespread commercialisation has been hampered, in part, by the use of precursors that are rarely homogeneous and are generally poorly characterised. Even when precursors are well characterised, their extent of reaction during geopolymer synthesis is not well known, leading to a disparity between targeted and actual compositional ratios. Small variations in compositional ratios, particularly Si:Al, can lead to dramatic changes in physical properties. A process for characterising precursors, focussing on their reactive component, will be described here, followed by methods that can be used to determine the extent of reaction in the final product. Characterising the final product is important, but it does not reveal what processes occur between mixing the precursors and setting of the solid geopolymer. We will also describe a method that can be used to track dissolution of precursors and subsequent evolution of the alkali-activated product, thus providing a more comprehensive picture of geopolymerisation. This paper demonstrates a link between precursor characterisation and the extent of reaction in order to provide those working with alkali-activated materials with additional knowledge enabling them to manufacture reproducible, high-quality products.","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"37 1","pages":"421-431"},"PeriodicalIF":0.5,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70791391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Beta-to-alpha transformation in cristobalite was examined by means of differential scanning calorimetry (DSC) to address how enthalpy, transformation hysteresis, and transformation onset temperature change upon repeated thermal cycling. Cristobalite powder was repeatedly cycled from 190 – 280 °C and back, cycling through the firstorder displacive transformation between high-temperature, cubic beta-cristobalite and low-temperature, tetragonal alpha-cristobalite. The enthalpy of the transformation did not changewith cycling, but the exothermic beta-to-alpha enthalpy at 1560 ± 27 J/mol was larger than endothermic alpha-to-beta enthalpy at 1260 ± 8 J/mol. Transformation onset temperatures and hysteresis varied systematically with repeated cycling of the transformation. The onset temperature of the beta-to-alpha transformation increased logarithmically with cycling, resulting in reduced undercooling and hysteresis. The onset temperature of the alpha-to-beta transformation decreased logarithmically with cycling, resulting in reduced super-heating and hysteresis. The reduced hysteresis indicates a lowered barrier to transformation. We propose this reduced hysteresis indicates particle refinement through microfracture caused by the -4.9% volume change on the beta-to-alpha transformation. This is supported by the observation of powder size dependence. Powder with particles finer than 38 μmhad no change on cycling, suggesting 38 μm is below the critical minimum size.
{"title":"Hysteresis upon Repeated Cycling through the Beta-Alpha Cristobalite Transformation","authors":"Hayward, A. Arbor","doi":"10.4416/JCST2014-00048","DOIUrl":"https://doi.org/10.4416/JCST2014-00048","url":null,"abstract":"Beta-to-alpha transformation in cristobalite was examined by means of differential scanning calorimetry (DSC) to address how enthalpy, transformation hysteresis, and transformation onset temperature change upon repeated thermal cycling. Cristobalite powder was repeatedly cycled from 190 – 280 °C and back, cycling through the firstorder displacive transformation between high-temperature, cubic beta-cristobalite and low-temperature, tetragonal alpha-cristobalite. The enthalpy of the transformation did not changewith cycling, but the exothermic beta-to-alpha enthalpy at 1560 ± 27 J/mol was larger than endothermic alpha-to-beta enthalpy at 1260 ± 8 J/mol. Transformation onset temperatures and hysteresis varied systematically with repeated cycling of the transformation. The onset temperature of the beta-to-alpha transformation increased logarithmically with cycling, resulting in reduced undercooling and hysteresis. The onset temperature of the alpha-to-beta transformation decreased logarithmically with cycling, resulting in reduced super-heating and hysteresis. The reduced hysteresis indicates a lowered barrier to transformation. We propose this reduced hysteresis indicates particle refinement through microfracture caused by the -4.9% volume change on the beta-to-alpha transformation. This is supported by the observation of powder size dependence. Powder with particles finer than 38 μmhad no change on cycling, suggesting 38 μm is below the critical minimum size.","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"6 1","pages":"55-62"},"PeriodicalIF":0.5,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70790013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Watolla, G. Gluth, P. Sturm, W. Rickard, S. Krüger, B. Schartel
The passive fire protection of steel structures and other load-bearing components will continue to gain importance in future years. In the present contribution, novel intumescent aluminosilicate (geopolymer-bound) composites are proposed as fire-protective coatings on steel. Steel plates coated with these materials were exposed to the standard temperature-time curve as defined in ISO 834 – 1:1999. The coatings partially foamed during curing and expanded further during thermal exposure, demonstrating their intumescent characteristic.Thermogravimetryandoscillatory rheometry determined that the intumescent behavior is attributed to a transition to a viscous state (loss factor > 1) in the temperature range of major water release, differing from conventional geopolymers. XRD and SEM images showed that the coatings had characteristics of ceramic or glass-ceramic foams after fire resistance testing, suggesting superior performance under challenging conditions. The thickness of the coatings influenced their foaming and intumescent behavior and thus the time for the coated steel plates to reach 500 °C. A number of additives were also studied with the best performance obtained from samples containing sodium tetraborate.Acoating of just 6mmwas able to delay the time it takes for a steel substrate to reach 500 °C to more than 30 minutes.
{"title":"Intumescent geopolymer-bound coatings for fire protection of steel","authors":"M. Watolla, G. Gluth, P. Sturm, W. Rickard, S. Krüger, B. Schartel","doi":"10.4416/JCST2017-00035","DOIUrl":"https://doi.org/10.4416/JCST2017-00035","url":null,"abstract":"The passive fire protection of steel structures and other load-bearing components will continue to gain importance in future years. In the present contribution, novel intumescent aluminosilicate (geopolymer-bound) composites are proposed as fire-protective coatings on steel. Steel plates coated with these materials were exposed to the standard temperature-time curve as defined in ISO 834 – 1:1999. The coatings partially foamed during curing and expanded further during thermal exposure, demonstrating their intumescent characteristic.Thermogravimetryandoscillatory rheometry determined that the intumescent behavior is attributed to a transition to a viscous state (loss factor > 1) in the temperature range of major water release, differing from conventional geopolymers. XRD and SEM images showed that the coatings had characteristics of ceramic or glass-ceramic foams after fire resistance testing, suggesting superior performance under challenging conditions. The thickness of the coatings influenced their foaming and intumescent behavior and thus the time for the coated steel plates to reach 500 °C. A number of additives were also studied with the best performance obtained from samples containing sodium tetraborate.Acoating of just 6mmwas able to delay the time it takes for a steel substrate to reach 500 °C to more than 30 minutes.","PeriodicalId":48807,"journal":{"name":"Journal of Ceramic Science and Technology","volume":"8 1","pages":"351-364"},"PeriodicalIF":0.5,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70791614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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