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Preparation of transparent advanced ceramic base on Al2O3.MgO
Chvíla, Martin ; Maca, Karel (referee) ; Pouchlý, Václav (advisor)
Ceramic materials are in general characterized by high hardness, high modulus of elasticity, excellent abrasion resistance, etc. These properties make ceramics among others useful in optically transparent applications. An ideal form of optically transparent ceramic material is monocrystalline. However, the monocrystalline fabrication is expensive and/or time consuming. From this point of view polycrystalline ceramics is preferred. But the polycrystalline transparent ceramics fabrication is fraught with complications such as porosity, inappropriate grain size and insufficient purity. These circumstances could be solved by using sintering additives. This master’s thesis compiles literature research summarizing modern technologies of advanced ceramics sintering and ceramic polycrystalline microstructure dependence on its optical properties. The experimental part of this thesis focuses on the fabrication parameters of polycrystalline advanced ceramics based on Al2O3MgO and evaluation of their optical properties. Polycrystalline magnesium-aluminate spinel with sintering additive contents 0; 0.3 and 0.6 weight % LiOH was fabricated by optimalisation of Spark Plasma Sintering cycle. Fully dense ceramic samples of polycrystalline magnesium-aluminate spinel with favourable optical properties in visible spectrum radiation were achieved. Real In-line Transmission RIT and Total Forward Transmittance TFT were analysed. RIT exceeded 84 % at wavelength of 633 nm and TFT exceeded 83 % at wavelength above 860 nm. The decisive factors in terms of the optical properties of ceramics sintered with sintering additives were the amount of time-spending at high temperatures and the purity of ceramic powders.
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High-speed sintering of ceramic materials
Chvíla, Martin ; Spusta, Tomáš (referee) ; Pouchlý, Václav (advisor)
Modern ceramic materials are of a key function in a number of applications in all industrial sectors. The process of preparation of the modern ceramic materials includes an important technological step – sintering. Recently methods operating also with sintering by an electric field have been used. These methods are called non-conventional sintering methods (Spark Plasma Sintering, Flash Sintering etc.) and they represent a promising progress in the manufacturing of advanced ceramic materials. These methods provides time and energy saving, and materials produced by these technologies can achieve better specific properties. The sintering in Spark Plasma Sintering have been in the past few years subject of intensive research. Nevertheless, all the sintering conditions (for example the sintering mechanism) in Spark Plasma Sintering are not completely clarified. The aim of this thesis is to summarize the findings about the preparation of advanced ceramic materials using the non-conventional methods of sintering. During experimental work, the effect of the heating rate while sintering by the Spark Plasma Sintering method on the amount of activation energy of sintering that is needed for sintering of the material ZrO2 + 3 mol. % Y2O3 with regard to the microstructure has been investigated. During the thesis was proved that the time and energetic efficiency is increased using the Spark Plasma Sintering method with higher rating rate (50 °C/min compared to 750 °C/min). The relative densities of samples manufactured by using different heating rate with constant pressure stayed almost unchanged. By using higher heating rates, it was possible to achieve a high relative density and shrinkage already at lower temperature. The method of Master Sintering Curve proved that the activation energy of sintering decreases when higher heating rates of sintering were used.
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Preparation of transparent advanced ceramic base on Al2O3.MgO
Chvíla, Martin ; Maca, Karel (referee) ; Pouchlý, Václav (advisor)
Ceramic materials are in general characterized by high hardness, high modulus of elasticity, excellent abrasion resistance, etc. These properties make ceramics among others useful in optically transparent applications. An ideal form of optically transparent ceramic material is monocrystalline. However, the monocrystalline fabrication is expensive and/or time consuming. From this point of view polycrystalline ceramics is preferred. But the polycrystalline transparent ceramics fabrication is fraught with complications such as porosity, inappropriate grain size and insufficient purity. These circumstances could be solved by using sintering additives. This master’s thesis compiles literature research summarizing modern technologies of advanced ceramics sintering and ceramic polycrystalline microstructure dependence on its optical properties. The experimental part of this thesis focuses on the fabrication parameters of polycrystalline advanced ceramics based on Al2O3MgO and evaluation of their optical properties. Polycrystalline magnesium-aluminate spinel with sintering additive contents 0; 0.3 and 0.6 weight % LiOH was fabricated by optimalisation of Spark Plasma Sintering cycle. Fully dense ceramic samples of polycrystalline magnesium-aluminate spinel with favourable optical properties in visible spectrum radiation were achieved. Real In-line Transmission RIT and Total Forward Transmittance TFT were analysed. RIT exceeded 84 % at wavelength of 633 nm and TFT exceeded 83 % at wavelength above 860 nm. The decisive factors in terms of the optical properties of ceramics sintered with sintering additives were the amount of time-spending at high temperatures and the purity of ceramic powders.
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GymLog, aplikace pro podporu cvičení v posilovně
Chvíla, Martin
Goal of this thesis is to create web application. This application should allow its users to log their progress in gym and help them see whether they are improving or not. For its implementation, technologies like JavaScript, VueJS, PHP, Laravel, AJAX, HTML and CSS were chosen. This application’s goal is to provide platform independent alternative to mobile apps.
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High-speed sintering of ceramic materials
Chvíla, Martin ; Spusta, Tomáš (referee) ; Pouchlý, Václav (advisor)
Modern ceramic materials are of a key function in a number of applications in all industrial sectors. The process of preparation of the modern ceramic materials includes an important technological step – sintering. Recently methods operating also with sintering by an electric field have been used. These methods are called non-conventional sintering methods (Spark Plasma Sintering, Flash Sintering etc.) and they represent a promising progress in the manufacturing of advanced ceramic materials. These methods provides time and energy saving, and materials produced by these technologies can achieve better specific properties. The sintering in Spark Plasma Sintering have been in the past few years subject of intensive research. Nevertheless, all the sintering conditions (for example the sintering mechanism) in Spark Plasma Sintering are not completely clarified. The aim of this thesis is to summarize the findings about the preparation of advanced ceramic materials using the non-conventional methods of sintering. During experimental work, the effect of the heating rate while sintering by the Spark Plasma Sintering method on the amount of activation energy of sintering that is needed for sintering of the material ZrO2 + 3 mol. % Y2O3 with regard to the microstructure has been investigated. During the thesis was proved that the time and energetic efficiency is increased using the Spark Plasma Sintering method with higher rating rate (50 °C/min compared to 750 °C/min). The relative densities of samples manufactured by using different heating rate with constant pressure stayed almost unchanged. By using higher heating rates, it was possible to achieve a high relative density and shrinkage already at lower temperature. The method of Master Sintering Curve proved that the activation energy of sintering decreases when higher heating rates of sintering were used.
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