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Synthesis of foamed bioceramics for potential medical applications
Doboš, Petr ; Šoukal, František (referee) ; Palou, Martin (advisor)
Cílem práce byla příprava porézních vzorků HAP pro potenciálně medicínské aplikace. HAP byl připraven metodou sol-gel a precipitační. Vzorky HAP byly podrobeny analýze FTIR, XRD, SEM. Takto připravený HAP byl napěněn pomocí houbové metody s jasně definovanými póry a pomocí polymerního a skleněného expanzelu s různou distribucí a velikostí pórů. U výsledných napěněných vzorků byla vyhodnocena mikrostruktura a povrchová analýza pomocí SEM, zjištěna porozita pomocí Hg porozimetru a sledována bioaktivita in vitro v SBF. Byly zjištěny jasně definované makro, mezo a mikro póry při různé distribuci. U houbové metody pomocí sol-gel došlo k vytvoření jasně definovaných a pravidelných pórů s monodisperzní porozitou. Dominantní velikost póru byla stanovena v rozmezí 1–5 µm. Celková porozita byla stanovena na 63,5 % s celkovým povrchem 3,048 1 m/g. Precipitační metodou s polymerním expanzelem došlo k polydisperznímu rozložení pórů s třemi hlavními fázemi v rozmezí: 50–100 µm, 5–10 µm a 0,5–1 µm. Celková porozita byla stanovena na 67,6 % s celkovým povrchem 19,090 3 m/g. Bioaktivita výsledných napěněných vzorků in vitro byla sledována po dobu 7 dnů v připraveném SBF. Při napěnění sol-gel houbovou metodou nevznikla výsledná bioaktivní vrstva. U precipitační metody napěněné pomocí polymerního expanzelu vznikla nepravidelná bioaktivní vrstva. Výsledky byly naměřeny pomocí SEM analýzy.
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Study of mechanism and kinetics of hexa-1,5-diene polymerisation catalyzed by phenoxy-imine titanium complex and MAO
Ševčík, Jan ; Cihlář, Jaroslav (referee) ; Hermanová, Soňa (advisor)
This diploma thesis is focused on study of polymerization of hexa-1,5-diene catalyzed by phenoxy-imine titanium dichloride (FI Ti) and methylaluminoxane (MAO) as cocatalyst. Effect of monomer concentration, polymerization temperature and cocatalyst/catalyst ratio on catalytic activity, molecular weights, polydispersities and particularly microstructure of prepared poly(hexa-1,5-diene) was studied. 1H NMR spectroscopy revealed that the poly(hexa-1,5-diene) microstructure contained methylene-1,3-cyclopentane (MCP) as well as vinyl tetramethylene (VTM) units. Kinetics of this polymerization was studied. Finally, copolymer of ethene and hexa-1,5-diene possessing incorporated pendant vinyl group was prepared.
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High-performance concretes based on the secondary raw materials
Sáček, Josef ; Brandštetr, Jiří (referee) ; Šoukal, František (advisor)
This work is devoted to study of physical-mechanical properties and structure of high performance concretes (HPC) based on portland cement. The attention is focused on possibility of substitution of economic high-cost components of concrete with utilization of secondary raw materials or cheaper components. Properties of raw materials and their influence on whole quality of concrete were tracked by various methods. Mechanical properties of prepared HPC samples were tested especially (compression and flexural strength) with further microscopic study of structure. Isoperibolic calorimetry and X-ray powder diffraction method were also used for concrete characterisation. These methods allowed to determine the influence of raw materials on prepared HPC and to carry out a certain optimization among price and quality of this material.
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Aluminium oxide ceramics microstructure modification for ballistic testing
Rolek, Ondřej ; Drdlík, Daniel (referee) ; Roleček, Jakub (advisor)
This bachelor thesis describes basic shaping methods of ceramic materials and drying processes of wet ceramics, with concern of slip casting method. The experimental part of this thesis presents the usage of slip casting method for preparation of Al2O3 ceramic plates, suitable for personal and vehicle ballistic protection. Tailoring of the slip casting plaster molds, with regard to the resulting properties of the Al2O3 ceramic body, in particular its relative density, is also described in this part. The influence of sintering temperature on final relative density of ceramic samples and on their microstructure especially their grain size is also shown in the practical. Bulk ceramic samples suitable for upcoming ballistic testing with low grain size (1,18 m) and high relative density exceeding 99 % were prepared from alumina.
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Welding of titanium alloys using electron beam
Schiffer, Martin ; Foret, Rudolf (referee) ; Havlík, Petr (advisor)
This bachelor´s thesis is focused on issue of welding of titanium alloys using electron beam. It is dedicated to description of principle of electron beam welding technology. There is described interaction of electron beam with the welded material, electron beam characterisation and configuration of device for electron beam welding. Next part is focused on evaluation of weldability of titanium alloys. It includes general description of weldability of materials, description, distribution and weldability of titanium alloys and finally evaluation of effect of electron beam welding on the microstructure. As an example, there is described effect of EBW on mechanical properties of alloy Ti-6Al-4V. In the end this technology is compared with other methods of fusion welding as laser beam welding, arc welding methods and plasma arc welding.
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Mechanical properties of Nodular Cast Iron prepared by method Tundish and process Initek
Vítek, Radovan ; Hotový, Ivan (referee) ; Věchet, Stanislav (advisor)
This bachelor thesis deals with a properties and production of nodular cast iron. The first section describes the classification, distribution and structure of nodular cast iron. The second part is focuses on the description of nodular cast iron, modification, inoculation and production. A strong effort is made on the production of nodular cast iron using the Tundish Cover method and the Initek process. In conclusion, the structure of the material is evaluated on samples that were delivered for metallographic analysis. The final evaluation of the structure of the material is used to compare the mechanical properties of a nodular cast iron produced by Tundish Cover method and Initek process.
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Grain growth kinetics study of advanced oxide ceramic materials
Kazda, Adam ; Kachlík, Martin (referee) ; Pouchlý, Václav (advisor)
The goal of this work was to study the grain growth kinetics of five different materials: tetragonal ZrO2 (doped 3mol.% Y2O3 and particle size 80 nm), two cubic ZrO2 (doped 8 mol.% Y2O3 and particle sizes 80 and 140 nm) and two hexagonal Al2O3 (with particle sizes 100 and 240 nm). These ceramic powders were isostatically pressed and then they were isothermally sintered at 3 different temperatures for 1-60 hours. The biggest coarsening was discovered during temperature increase to sintering temperature. The dwelt at sintering temperature was not so important for coarsening. The activation energy of grain growth QG, growth exponent n and kinetic constant k0 were discovered for four materials. The activation energy of grain growth was 511±49 kJ/mol for tetragonal ZrO2, 645±84 kJ/mol for cubic ZrO2 a 428±75 kJ/mol a 606±24 kJ/mol for Al2O3. Possibility of kinetic window of sintering process for cubic ZrO2, tetragonal ZrO2, and Al2O3 with particle size 240 nm (doped MgO) were discovered by comparison of established activation energy of grain growth QG with activation energy of sintering QS from literature. Kinetic window of sintering process wasn’t found for high purity alumina with particle size 100 nm.
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Study of AlSi protective coating after degradation
Vítková, Gabriela ; Řičánková, Veronika (referee) ; Hutařová, Simona (advisor)
Materials used for high temperature applications works in a very aggressive environment (oxidation, hot corrosion, erosion, fatigue, creep). Demands on these materials are very high. Nickel-based superalloys show the certain stability in this environment. Improved resistance to oxidation and hot corrosion can be achieved by using protective layers such as diffusion barriers. This thesis is focused on changes of microstructure and properties of AlSi layer applied by „slurry“ method on nickel-based superalloy Inconel 713 LC, due to long-term thermal exposition at 800, 900 a 1000 °C.
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Cutting ceramics
Vaverka, Ivo ; Sámelová, Vendula (referee) ; Humár, Anton (advisor)
The Bachelor Thesis is focused on cutting ceramics which belongs to tool materials. The first part deals with sorting, application and characterization of basic materials for cutting tools. The cutting ceramics itself is thoroughly analysed from a historical perspective, default materials, production, physical and mechanical qualities and microstructure in the second part. The last part contains the assortment of CeramTec, Greenleaf and Saint-Gobain.
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Structure and properties of welded joints of steam turbine rotor
Machala, Jan ; Hutařová, Simona (referee) ; Juliš, Martin (advisor)
This thesis deals with the assessment of the structural-mechanical properties of welded joints of steam turbine rotor. Experimental weld material is low alloy steel 30CrMoNiV5-11 in the state after the artificial degradation. The theoretical part of the literary researches the issue, focusing on the weldability of different types of steel used in the energy industry, the metallurgical processes in welding and provides an overview of the most important methods of welding. Great attention is paid to the evaluation of weld quality in accordance with relevant standards and destructive and non-destructive testing of welded joints. In the experimental part of this work was carried out measurements of hardness and microhardness of the weldment by Vickers and evaluation of the microstructure by light microscopy. The obtained values and information about the properties of the material after artificial degradation were compared with previously obtained experimental results in the default state (after annealing).
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