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Structural analysis of austenitic weld joints
Procházka, Robert ; Foret, Rudolf (referee) ; Havlík, Petr (advisor)
The bachelor thesis deals with structural analysis of austenitic weld joints by using methods of material science. The theoretical part of the thesis summarizes the problematics of welding of high-alloy steels. After the general definition of welding and weldability of high-alloy steels, the thesis focuses on structural adjustments including welding defects during the welding process. Selected methods of fusion welding that were used to create these welds are mentioned in the second half of the theoretical part. The experimental part covers the structural analysis of the welds, which consists of microstructure evaluation, chemical composition analysis, and microhardness test.
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Upgrade of the UHV manipulator for SIMS and LEIS methods
Dao, Tomáš ; Polčák, Josef (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis deals with the design and the construction of the manipulator, which operates under ultra high vacuum. In the first section, the original design and realization of the manipulator with six motion axis is introduced. Second section deals with the modifications of the manipulator. Advantages and disadvantages of the design are discussed and a new design of the manipulator, based on the experience from manipulator operation, is projected. Section is mainly focused on the design of the sample rotation using a stepper motor working in the ultra high vacuum. The new Faraday cup was also designed and tested. The last section contains the LEIS structural analysis measurement using the manipulator.
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Utilization of methods of physicochemical and structural analysis in characterization of biosurfactants
Nešpor, Tomáš ; Hurčíková, Andrea (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the very actual topic of biosurfactants. In the theoretical part of the thesis, a literature review on this topic was carried out and on the basis of this research, physicochemical and structural analysis techniques suitable for testing these substances were selected. In the practical part, the model biosurfactants were first characterized by standard methods used to study these compounds. Fourier transform infrared spectrometry was chosen as a standard technique of structural analysis. As an example of a universal technique for the study of aggregation behavior was used tensiometry. In the next part of the thesis there were designed and optimized alternative techniques usable for fast and inexpensive physicochemical analysis of these substances. It was mainly a microplate assay and its modified alternatives. Thus, the methods of low sample consumption, but also effective in confirming the presence and a possible amount determination of the biosurfactant content in the solution. The result of this work is a few simple methods that have been proven effective in studying biosurfactants.
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Application of different fractionation techniques for structure determination of ICP
Dostálová, Dagmar ; Kratochvíla,, Jan (referee) ; Buráň,, Zdeněk (advisor)
Impact E/P copolymer (ICP) is produced using gas-phase polymerization catalysed by Ziegler-Natta catalysts. This material with its excellent mechanical properties is used in many industries, for example in automotive industry to produce bumpers or instrument panels. Its properties depend on chemical structure which was analysed using DSC, 13C NMR and GPC. It was used 6 different samples of ICP for studies, the chosen samples have different ratio between ethylene and propylene in their copolymer phase. The samples were fractionated using preparative TREF and solvent extraction to obtain fractions, which composition depends on elution temperature. Obtained fractions and original samples were subsequently analysed using above-mentioned methods.
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Influence of E/P copolymer composition on impact copolymer properties
Dostálová, Dagmar ; Kučera, František (referee) ; Buráň, Zdeněk (advisor)
Houževnatý E/P kopolymer se vyrábí polymerací v plynné fázi, která je katalyzovaná Ziegler–Nattovými katalyzátory. Tento materiál s výbornými mechanickými vlastnostmi je používán v mnoha průmyslových odvětvích, např. v automobilovém průmyslu na výrobu nárazníků aut a palubních desek. Jeho vlastnosti závisí na chemické struktuře, která byla zkoumána pomocí metod DSC, SSA, 13C NMR, ATREF a FTIR. Výsledky analýz byly porovnány s mechanickými vlastnostmi vzorků - modulem pružnosti v ohybu a nízkoteplotní vrubovou houževnatostí dle Charpyho. Pro studium vlivu složení na mechanické vlastnosti bylo použito 5 různých vybraných vzorků houževnatého kopolymeru E/P s různým poměrem ethylenu a propylenu v kopolymerní fázi, které byly frakcionovány pomocí o-xylenové extrakce za účelem rozdělení materiálu na krystalickou část, složenou z krystalického E/P kopolymeru a PP, a amorfní část, tvořenou E/P kaučukem. Získané frakce i původní vzorky byly následně analyzovány výše uvedenými metodami.
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Influence of Explosive Hardening on the Structure and Characteristic of Hadfield Steel in Terms of use in the Railway Transport
Havlíček, Petr ; Podrábský, Tomáš (referee) ; Nesvadba,, Petr (referee) ; Schmidtová,, Eva (referee) ; Stránský, Karel (advisor)
The high alloyed austenitic manganese steel, the Hadfield steel, thanks to its good wear resistance of the work surface and maintaining the high toughness of the internal material in the same time, is successfully applied for casted crossings. The crossings are the most dynamic stressed components in the railway turnouts. Thanks to low surface and sub-surface hardness the occurrence of plastic deformation and the progressive wear of the crossing running surfaces can be found since the initial stages of the crossing operational life. One possibility how to increase the surface and the sub-surface hardness and this way improve the dimensional stability and the crossing lifetime as well is to apply the explosive hardening of the crossing running surfaces. The technology mentioned above means the application of the explosives in the imminent nearness to the running surface of the crossing, when the high pressure wave acting within the extremely short period actuates the plastic deformation of the material structure. The work deals with analysis of influence of explosive hardening on the structure and characteristic of Hadfield steel. The explosive hardened samples have the surface and the sub-surface hardness checked and the microscopic analysis and X – ray diffraction is applied, including the TEM analysis as well carried out by the transmission electronic microscope. The characteristics experimental testing including outcomes from assessment of the contact – fatigue load of the explosive hardened Hadfield steel samples are the part of the work as well. As an experiment final part the outcomes of the long –term validation, the surface hardness and wear of the crossing running surfaces of the explosive hardened crossing already installed into the Czech Republic railway track are introduced as well.
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Preparation and analysis of experimental refractory alloy
Krupica, Roman ; Štěpánek, Roman (referee) ; Jan, Vít (advisor)
This thesis is focused on a preparation and especially on an analysis of an experimental Fe, Cr, W, Ni, Al, Ti refractory alloy. The first, theoretical, part of the work deals with refractory materials problematics in general. The second part of the work, experimental, is focused on the process of material preparation and its partial analyses in terms of hardness, but mainly in terms of structure. Light microscopy and scanning electron microscopy were used for these analyses, and energy dispersive spectrometry was used to analyze the chemical composition. The achieved results in all material states indicate that titanium nitrides randomly occur in the structure due to the nitrogen contamination. In the cast state, the material appears to be almost completely homogeneous without any significant casting defects. At grain boundaries, there is a uniform structured Laves phase population based on tungsten. After annealing at 800 °C/1h small fine and evenly distributed precipitates of the Laves phase occur together with even smaller precipitates of an intermetallic phase probably based on nickel and aluminum. Also, the amount of tungsten in the Laves phase at the grain boundaries was increased. During annealing at 1000 °C/5h, the precipitation particles of the Laves phase significantly coarsened and the occurrence of the intermetallic precipitates became uneven. At the same time, the Laves phase at the grain boundaries was again found to have more tungsten in it.
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Design of steam generator tube bundle
Klíma, Martin ; Lošák, Pavel (referee) ; Nekvasil, Richard (advisor)
Diploma thesis is focused on analisis of the steam generator tube bundle on the basis calculation by the finite elements method and softwaru ANSYS. Next it will also také account of job descriptions and methods of operation of the equipment propřed plan revision kontrol points that will be most critical. Annexes included documentary of model from the SolidWorks.
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Complex structural characterization of hydrogels based on semi interpenetrating biopolymer networks.
Trudičová, Monika ; Krzyžánek, Vladislav (referee) ; Sedláček, Petr (advisor)
The content of this diploma thesis was testing the applicability of available structural analysis techniques on a appropriate model hydrogel system. The main aim was to evaluate the advantages and disadvantages of selected structural analysis techniques and the influence of the composition change of the hydrogel system on its internal structure. Semi-interpenetrated hydrogels based on agarose of different concentration were chosen as model system, this type of material was chosen for simple and repeatable preparation and also for its application potential. Electron microscopy (SEM, cryoSEM), mercury porosimetry and turbidimetry were chosen as structural analysis techniques. Experimental results could be used to improve knowledge about the influence of hydrogel composition on its structure and the comparison of chosen techniques will be used for the choice of appropriate structural analysis in the future, which will be applicable to other hydrogel systems as well.
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