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Synthesis of ferroelectric and dielectric ceramic composite materials
Čípová, Eva ; Salamon, David (referee) ; Částková, Klára (advisor)
The topic of the thesis is preparation of ferroelectric and dielectric composite materials, particularly the work deals with the preparation of barium strontium titanate. In the theoretical part the possibilities of BST synthesis and its processing are described. The experimental part deals with precipitation synthesis of barium strontium titanate. Prepared powders were characterized in terms of morphology and phase composition. Further, pressureless sintering and hot isostatic pressing (HIP) were used for preparation of dense ceramics. Pure BST powders, that were formed and sintered, were prepared by sol-gel precipitation synthesis. The highest density was reached by slow sintering cycle (slow increase of temperature and delay during sintering) and sintering by HIP.
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Synthesis of bioceramic materials based on hydroxyapatite
Kočicová, Pavla ; Králová, Marcela (referee) ; Částková, Klára (advisor)
The thesis deals with the precipitation synthesis of nanoparticle hydroxyapatite with goal to study the influence of reaction conditions on the morphology of the particles. The theoretical part is focused on biomaterials, bioceramics and phosphates characterization. Further the work is focused on hydroxyapatite, its characteristics and possible synthesis in particular. The synthesis of hydroxyapatite precipitation is described in the experimental part. Syntheses were performed at a reaction temperature of 0-80 °C at pH = 8-11, at the aging time of 0-24 h, in the presence of surfactant and the chelating agent and with the post-precipitation hydrothermal or ultrasonic treatment. For characterization of the prepared powders, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), laser diffraction (LD) and the analysis of the specific surface area (BET) were used. Pure hydroxyapatite powders or a mixture of hydroxyapatite and tricalcium phosphate were prepared by precipitation syntheses. HA particle morphology was strongly affected by the reaction temperature – with increasing temperature the larger particles with a clearer morphology were formed, mostly in the rod shape. Postprecipitation hydrothermal treatment had a significant influence on the morphology of HA particles – it caused the formation of spherical or slightly elongated particles. The reaction medium of water/ethanol significantly affected the particle morphology – it inhibited the particle growth.
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Machinable bioceramics prepared by gelcasting method
Kolář, Martin ; Částková, Klára (referee) ; Trunec, Martin (advisor)
In the diploma thesis, overviews of the existing literature focused on the gelcasting method and based on the findings were prepared aqueous slurries of zirconium oxide for gelcasting method. These suspensions were examined for the influence of the content ceramics powder, type and content of dispersants and volume of initiator on viscosity of aqueous suspensions and process of polymerization. Optimum ceramic suspension had 45 vol.% of ceramic powder which was stabilized by 0,5 weight % of dispersant Dolapix CE 64. Polymerization running at room temperature was initiated by 0,175 weight % of ammonium persufate without accelerator. Microstructure of prepared ceramic blanks and sintered bodies was compared with body prepared by isostatic pressing. For the machining tests were prepared blanks in disc-shaped.
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Preparation and properties of ferroelectric ceramic materials
Vykoukalová, Tereza ; Maca, Karel (referee) ; Částková, Klára (advisor)
The aim of the work was a processing of ceramic material based on BST for ferroelectric application. Wet chemical techniques based on precipitations and sol-gel methods with ultrasound, hydrothermal or mechanochemical treatment supporting deaglomeration and reducing particle growth were used for BST ceramic powder synthesis. Suitable powders were selected by the evaluation of particle morphology, size and agglomeration, from these powders BST bulk ceramic with defined phase composition and morphology applicable for ferroelectric applications was prepared. It was found, that the most suitable method for preparation of phase pure and nanosized BST powder was sol-gel synthesis with solvothermal treatment (200 °C/48 h). Ceramic with relative density of 85 % TD and with the average grain size of about 1, 22 µm was prepared by pressing and sintering of the powder synthesized by the sol-gel method.
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Shaping of bioceramics by dip-coating
Gockert, Radek ; Částková, Klára (referee) ; Salamon, David (advisor)
The presented bachelor thesis describes basic shaping methods of bioceramic materials, especially a description of the dip-coating method. Subsequently, the experimental part of the thesis presents the usage of this method for the preparation of ceramic micro units sintered from hydroxyapatite, and containing micro channel suitable for transporting media in living tissue. Tailoring of the process leads to the formation of variable droplets and films, subsequent sintering process used temperature control and calcination of the starting powder to achieve microstructure with controlled porosity and grain size. Micro units with diameter from 50 µm to 1 mm with variable porosity and micro channels were prepared from hydroxyapatite.
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Modern processing methods of porous bioceramics
Šťastný, Přemysl ; Částková, Klára (referee) ; Trunec, Martin (advisor)
Bachelor thesis is written with focusing to bioscaffolds. Thesis is devided into three parts. First part is focused to colloid suspensions, their preparation and consolidation. Second part is focused to preparation methods of porous ceramics. The third part describes scaffolds and their use in medicine. Practical part is focused to gels preparation.
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Study of preparation of ceramic membranes
Matějková, Michaela ; Částková, Klára (referee) ; Bartoníčková, Eva (advisor)
In this bachelor thesis the literature retrieval concerning the preparation of ceramic membranes suitable for power applications (membrane reactors, fuel cells) and materials suitable for their preparation, was summarised. Based on that literature retrieval the glycine-nitrate syntheses of selected ceramic materials were performed. As starting material was chosen zirconate structure (Zr-Ba-O), which was doped by cerium, iron, aluminium and manganese ions. The resulting powders were further processed to solid membranes by unaxial pressing and sintering (density of sintered bodies about 93 % t. d.). Then the influence of dopants on the properties of the powders and ceramic membranes were studied. The evaluation of properties (as phase composition, powders morphology and microstructure of ceramic bodies) was performed by x-ray analysis, scanning electron microscopy, a specific surface analysis and simultaneous thermal analysis.
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Synthesis of functional ceramic powder materials
Čípová, Eva ; Maca, Karel (referee) ; Částková, Klára (advisor)
The theme of the work is electroceramic materials, particularly materials based on perovskites. The theoretical part describes electroceramic materials, their applications and possibilities of their synthesis. The experimental part focuses on the synthesis methods in liquid media and solid phase of barium strontium titanate. The prepared powders were characterized by morphology, phase composition and particle sinterability. It was found that weakly agglomerated particles with a single phase composition, perspective for the preparation of dense bulk ceramics, were prepared by the metod in liquid phase, especially by precipitation.
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Synthesis of ceramic powder materials in the presence of the ultrasound field
Kočicová, Pavla ; Bartoníčková, Eva (referee) ; Částková, Klára (advisor)
The thesis concerns the synthesis Ceric Oxide, Samarium Oxide and Samarium doped Cerium Oxide. The theoretical part is focused on the characteristics, applications and possibilities of the Cerium Oxide synthesis. The experimental part describes the precipitation of the Cerium Oxide powder. The synthesis of the powders were proceeded in the normal conditions or in the presence of ultrasonic field. For the purposes of description of the ready powders the x-ray diffraction (XRD) and the raster electron microscopy (SEM) were used. The ceramics were made of the selected powders where the structure was described by SEM, the density by Archimedes´Method and the grain size by grid-line intersect method. Using the precipitation synthesis, the pure powders of Ceric Oxide, Samarium Oxide and Samarium doped Cerium Oxide were prepared. The powder morphology was strongly involved by the pH level and by ageing time. The ultrasound was accelerating the ageing. At the values of pH > 11 the rodlike particles were created. The ageing time and the ultrasound supported the creation of the rodlike particles. The ceramics made of the powder with the presence of the rodlike morphology showed the density up to 97,14% of the theoretical density.
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