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Effect of the Composition of Alkali Activator on the Properties of Geopolymer Materials
Rinnová, Martina ; Bayer,, Patrik (referee) ; Rovnaník, Pavel (advisor)
The master thesis discusses the alkali-activation of aluminosilicate material (metakaolin), specifies the main components of geopolymer mixture, evaluates the influence of geopolymer mixture composition and the influence of other factors on final properties of geopolymer. Results of the mechanical properties and microstructure of the geopolymer pastes made out of metakaolin activated by various amounts (50–110 % by weight of metakaolin) of liquid water glass (with varying modulus from 0,5 to 3,0) or NaOH as well as KOH solution are presented in the experimental part.
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The use of micro and nanotechnology to develop ultra high strength and high performance concrete with special features
Vlč, Viktor ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The use of nanotechnology has become wide spread in all branches of science. Nanotechnology help us to understand microstructure and due to the world has started to produce new materials. One of many examples carbon nanotubes (CNTs). In diploma thesis I tried to find the way of successful introduction into concrete mixture. I was studying influence of CNTs and other nano particles and I was comparing them with referential samples (without CNTs). Also I tested the improvement of mechanical characteristics of concrete. The morphology of nano particles was studied using Scanning Electron Microscopy (SEM). The results show that introduction of nanoparticles to results in increasing strength and higher density. That is why High Performace Concrete so resistant and durable.
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Photonic crystal fibers
Dočkal, Martin ; Tejkal, Vladimír (referee) ; Šporik, Jan (advisor)
This graduation thesis deals with use of unconventional optical fiber with the intention of photonic crystal fiber. There are described types of photonic crystal fiber, their physical, optical and transfer characteristics. There is explained what are the photonic crystals, principle of their function and possible types of crystals. There are also detailed types of photonic fiber commonly used in the optical fiber branch. There is also explained photonic crystal fiber its structure a hierarchy of its types. In this thesis are described and demonstrated different kinds of photonic optical fiber and their use. There is demonstrated principle of one-dimensional periodical structure of Bragg fiber using simulation software. There can be seen graphical comparison of the simulated optical fiber core to commonly obtainable fiber. Outcome of this graduation thesis should be explanation of function of photonic crystal fiber and possibility of finding new type of fiber with optimal dispersion characteristics for use in fiber optics.
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Nickel coatings on magnesium alloys
Kosár, Petr ; Richtera, Lukáš (referee) ; Zmrzlý, Martin (advisor)
This diploma thesis is focused to nickel coatings on magnesium alloys. At the introduction of this work is briefly commented phase composition of AZ91 alloy, which is followed by detailed description of five very different theories of Ni-P coatings formation. Theoretical part is ended by review aimed to current states of development in areas of chemical nickel coating, influence of AZ91 alloy microstructure to current less deposition and possibility of surfactants influence to decrease of surface roughness. In experimental part of this thesis was the morphology and composition of Ni-P coatings including interlayers dependence on chemical composition of nickel-plating bath and magnesium alloy surface pre-treatment investigated using scanning electron microscopy and inverted optical microscopy. Average phosphorus content was obtained using energy dispersive analysis. Closing part of experimental part was dedicated for mechanical properties of coatings by micro-indentation analysis.
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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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