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Preparation of hybrid ceramic materials by ice-templating
Roleček, Jakub ; Lenčéš,, Zoltán (oponent) ; Jankovský,, Ondřej (oponent) ; Salamon, David (vedoucí práce)
Ice-templating, also known as freeze-casting, is a relatively simple, inexpensive, and very versatile technique to fabricate porous ceramic scaffolds with the controlled microstructure. The prepared scaffolds are used for preparation of hybrid ceramic composites or as bioceramic scaffolds. Hybrid ceramic composites are based on mimicking the architecture of natural/biological materials and structures. The motivation is to emulate nature’s toughening mechanisms by infiltration of polymers into ceramic structures. However, the main problem for an application is size of the prepared scaffolds. Preparation of large scaffolds by ice-templating method requires achieving controlled ice crystals growth throughout the whole sample volume. Thus it is necessary to precisely control the ice-templating process to obtain the well-defined lamellar architecture. Biological activity of bioceramic materials depends on a combination of physical and chemical characteristics that are strongly related to their microstructure. The scaffold porosity has to be interconnected with a sufficiently large pore size for successful bone tissue growth within the whole volume of an implant. Presented Ph.D. dissertation work was focused on scale up of the ceramic scaffolds prepared by ice-templating, creation of multiscale porosity inside the scaffolds, and preparation of hybrid ceramic composites for a ballistic protection. Ceramic suspensions for ice-templating were successfully prepared from different powders (mainly hydroxyapatite and alumina) with different solid loadings of ceramic powder from 7.5 vol.% up to 45 vol.%. The influence of suspension additives on formation of lamellar roughness and interlamellar bridging, and impact of these microstructural elements was studied. Hybrid alumina/polymer composites were successfully designed and prepared from ice-templated alumina plates with lamella length up to 70 mm and various polymeric resins. Mechanical performance of hybrid alumina/epoxy resin composites was tested and the results showed that ice-templating reveals to be the robust method for production of hybrid ceramic-polymer composites with good strength/density ratio. However ballistic tests of ice-templated alumina/polymer hybrid composites revealed that majority of composites presented in this work were not able to efficiently stop armor piercing projectiles. Combination of ice-templating and indirect rapid prototyping has been shown to enable manufacturing of bioceramic scaffolds for bone replacement from hydroxyapatite with multiscale porosity which could prove to be beneficial for the development of highly porous bioactive scaffolds with enhanced biological performance. Ice-templating also significantly modified the phase composition change during the sintering of hydroxyapatite scaffolds.
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Preparation of hybrid ceramic materials by ice-templating
Roleček, Jakub ; Lenčéš,, Zoltán (oponent) ; Jankovský,, Ondřej (oponent) ; Salamon, David (vedoucí práce)
Ice-templating, also known as freeze-casting, is a relatively simple, inexpensive, and very versatile technique to fabricate porous ceramic scaffolds with the controlled microstructure. The prepared scaffolds are used for preparation of hybrid ceramic composites or as bioceramic scaffolds. Hybrid ceramic composites are based on mimicking the architecture of natural/biological materials and structures. The motivation is to emulate nature’s toughening mechanisms by infiltration of polymers into ceramic structures. However, the main problem for an application is size of the prepared scaffolds. Preparation of large scaffolds by ice-templating method requires achieving controlled ice crystals growth throughout the whole sample volume. Thus it is necessary to precisely control the ice-templating process to obtain the well-defined lamellar architecture. Biological activity of bioceramic materials depends on a combination of physical and chemical characteristics that are strongly related to their microstructure. The scaffold porosity has to be interconnected with a sufficiently large pore size for successful bone tissue growth within the whole volume of an implant. Presented Ph.D. dissertation work was focused on scale up of the ceramic scaffolds prepared by ice-templating, creation of multiscale porosity inside the scaffolds, and preparation of hybrid ceramic composites for a ballistic protection. Ceramic suspensions for ice-templating were successfully prepared from different powders (mainly hydroxyapatite and alumina) with different solid loadings of ceramic powder from 7.5 vol.% up to 45 vol.%. The influence of suspension additives on formation of lamellar roughness and interlamellar bridging, and impact of these microstructural elements was studied. Hybrid alumina/polymer composites were successfully designed and prepared from ice-templated alumina plates with lamella length up to 70 mm and various polymeric resins. Mechanical performance of hybrid alumina/epoxy resin composites was tested and the results showed that ice-templating reveals to be the robust method for production of hybrid ceramic-polymer composites with good strength/density ratio. However ballistic tests of ice-templated alumina/polymer hybrid composites revealed that majority of composites presented in this work were not able to efficiently stop armor piercing projectiles. Combination of ice-templating and indirect rapid prototyping has been shown to enable manufacturing of bioceramic scaffolds for bone replacement from hydroxyapatite with multiscale porosity which could prove to be beneficial for the development of highly porous bioactive scaffolds with enhanced biological performance. Ice-templating also significantly modified the phase composition change during the sintering of hydroxyapatite scaffolds.
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