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Hybrid titania-silica layers on polymeric supports
Bednárková, Jana ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
This bachelor thesis deals with titania-silica photocatalytic layers on polymeric supports. The theoretical part involves the study of properties and possibilities of preparing the layer and it is mainly focused on the influence of silica on the nature of layers. The experimental part of this thesis investigates the influence of layer thickness on the degradation rate of 4 different dyes.
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Pozzolanic Activity of Silicon Dioxide
Barek, Jaroslav ; Žižková, Nikol (referee) ; Rovnaníková, Pavla (advisor)
The aim of this bachelor's thesis is to investigate and identify the present status of resources with dominant amorphous silicon dioxide content and summarize feasible test methods to assess pozzolanic activity. The use of pozzolan as a partial replacement of Portland cement reduces the carbon dioxide emitted per tonne of product and can also improve various physical properties of the resulting cementitious composites. Assessment of the pozzolanic activity of cement replacement materials is increasingly important because of the economic sustainability of cementing materials. The pozzolanic activity of wheat straw ash, silica fume, nanosilica, two diatomites, glass powder and expanded perlite have been investigated and compared using the strength activity index test, the modified Chapelle test and the pozzolanicity test in accordance with the European Standard EN 196-5. From an experimental investigation of seven different pozzolans, the following main conclusions can be drawn. In the case of an acid-base titration (determination of [OH–], the procedure specified in EN 196-5) is better to use Tashiro (mixed indicator) instead of required methyl orange, Tashiro changes color at the endpoint of a titration distinctly. Strength activity index: the procedure used was based on EN 450-1. In its current form, this procedure is misleading because of two other significant properties of the pozzolan, namely its density and its water-reducing/increasing capabilities. Based on the results of our experimental investigation, the current testing procedure is evaluated against an alternative in which the 25% pozzolan replacement for cement is performed on a volumetric basis and the volume fraction of water is held constant.
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Preparation of photocatalytically active layers of titanium dioxide
Šeffer, Lukáš ; Jančovičová, Viera (referee) ; Veselý, Michal (advisor)
This bachelor work gives an overview about preparation of titanium dioxide and silicon dioxide thin films by sol-gel process, using coating methods as spin coating, dip coating, capillary and cell coating, flow coating, spray coating, pyrosol process, chemical vapour deposition and printing. The procedures of composite films preparation obtained by mixed sols of titanium dioxide and silica dioxide are also discussed together with preparation of double layer films, when titanium dioxide is coated on glass substrate covered by a silica dioxide layer. The methods of photocatalytic activity testing are the important part of this work.
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Mineralizers Using in the Silica Materials Production Process
Maňák, Jan ; Sokolář, Radomír (referee) ; Nevřivová, Lenka (advisor)
Silica bricks is a refractory material whitch is used mainly in glass furnaces, coke oven bateries and hot blast stoves. Silica bricks constitute of the crystalline phases cristobalite, tridymite, glass phase and unconverted quartz. Content of these phases influences eventual properteis of silica bricks. This thesis deals with influence of the different kind of mineralizers, method of homogenization and length of firing on the content of these phases and eventual properties of silica bricks.
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Mineralogical composition of silica brick.
Pospíšil, Dušan ; Kotouček, Miroslav (referee) ; Nevřivová, Lenka (advisor)
This Bachelor´s thesis deals with the mineralogical composition of dense silica bricks. Silica bricks is a siliceous refraktory material that contains up to 99% of silicon dioxide, which is used mainly for the construktion of coke oven batteries, glass furnaces and heaters of blast-furnace wind. The main emphasis in case of silica bricks is put on the content of crystalline phases, which are the residual untransform quartz, tridymite, cristobalit and glass phase. These stages affect the resulting properties of dinas substantially. The main goal of this Bachelor´s thesis is to evaluate the impact of firing on the mineralogical composition of silica bricks and to its dilation at elevated temperatures.
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Manufacturing of calcium phosphates and silica based scaffolds for bioapllications
Virágová, Eliška ; Hadraba, Hynek (referee) ; Částková, Klára (advisor)
The aim of this diploma thesis was to prepare porous bioceramic scaffolds based on calcium phosphates and calcium phosphates doped with silica. Scaffolds are intended to be used in bone tissue engineering. Two main preparation methods were used for the creation of scaffolds – replica method and direct foaming method. Theoretical part of the diploma thesis is focused on a general description of the skeletal system, biomaterials and methods of preparation of highly porous calcium phosphate ceramics. Experimental part contains a description and the results of prepared scaffolds by above mentioned methods. The preparation process by the direct foaming method was optimized to obtain a defined structure. Calcium phosphate scaffolds containing 0–20 wt.% SiO2 were sintered and studied in terms of material characteristics (phase composition, pore size and porosity, microstructural study by scanning electron microscopy (SEM)), bioactive properties (simulated body fluid (SBF) interaction tests and tests of simulated degradation) and mechanical properties in order to evaluate the effect of silica doping. Scaffolds prepared by both methods were composed of a mixture of hydroxyapatite and/or tricalcium phosphate and cristobalite and wollastonite with comparable porosity in the range of 80–88 %. The pore size of the scaffolds prepared by the direct foaming method reached the interval of 5–250 µm opposite to template method reached the pore size up to 430 µm. The SBF interaction tests and tests of the simulated degradation confirmed the bioactive behavior of the prepared scaffolds and their ability to degrade under the simulated conditions. The scaffolds prepared by the direct foaming method showed better mechanical properties (compressive strength up to 1,8 MPa) than the scaffolds prepared by the template method. The results showed that the prepared scaffolds are suitable and promising for potential applications in bone tissue engineering.
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Optimization of Working Mass Composition for Dense Silica Bricks Production.
Maňák, Jan ; Lang,, Karel (referee) ; Nevřivová, Lenka (advisor)
A silica bricks is a refractory material which is used mainly in coke industry, glass industry and metallurgy. This material constitute of the quartz modifications. Compact silica is an irreplaceable part of the coke battery and its compactness and robustness is important for quality and long endurance. Very important for large compactness is a grain curve of work matter. This thesis deals with influence of different grain of work matter.
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