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Mechanical properties of optical thin films
Tomáštík, J. ; Čtvrtlík, R. ; Šebestová, Hana ; Schovánek, Petr ; Jankůj, J. ; Hrabovský, Miroslav
Mechanical properties of optical thin films and coatings are very important for their reliability, because they are often exposed to rough conditions in service. Mechanical attributes of films, that determine their behavior, are in the center of interest. In this paper, mechanical properties of optical thin films deposited on various types of glass substrates were examined. Assessment of such properties was performed using instrumented nanoindentation (hardness, elastic modulus, elastic and plastic work done by indentation) and scratch test (critical loads corresponding to the onset of specific failure). The failure modes of thin films were discussed.
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Characterization of plasma during organosilicone thin film deposition using haxamethyldisiloxane monomer
Blahová, Lucie ; Mazánková, Věra (referee) ; Krčma, František (advisor)
The aim of this thesis is plasma diagnostic during deposition of thin films based on organosilicones. Hexamethyldisiloxane was used as a precursor for plasma deposition in the presence of oxygen, and the diagnosis was performed by using optical emission spectroscopy. The theoretical part summarizes the basic characteristics of plasma and processes occurred at plasma polymerization and deposition. It also deals with thin films and their use in coating materials. A relatively large part is devoted to the specification of the physical-chemical nature of the used analytical method – optical emission spectroscopy. Finally, the principles of rotational, vibrational and electron temperature calculations are described. The contemporary deposition process was carried out in continuous and pulsed mode of radiofrequently excited capacitively coupled discharge. The effects of monomer flow rate, plasma power and duty cycle on the deposition process were studied. In the individual spectra, atomic hydrogen lines of Balmer’s series as well as an atomic oxygen line were identified. Molecular bands of CO have been identified as Angstrom’s system and 3. positive system. In the case of the identified fragments, the intensity dependencies on the monomer concentration in mixture, plasma power and duty cycle were detected. Electron temperature of plasma was also calculated using the relative intensities of atomic hydrogen lines of Balmer’s series. Vibrational and rotational temperature could not have been determined because no suitable fragments for their determination were found in the spectrum. Based on findings mentioned above, partial composition of plasma and some of its properties were estimated. The subject of the further research will be determination of the exact content and structure of the thin films and investigation of other plasma characteristics. Plasma deposition is influenced by many factors, and the study of their optimal combination for the most efficient deposition process is a goal for the future research.
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Černé povrchy pro použití v kryotechnice
Králík, Tomáš ; Hanzelka, Pavel ; Musilová, Věra ; Srnka, Aleš
Surfaces with high absorption or emission of thermal radiation are often needed in cryogenic and space applications. It is more difficult to realize a sufficiently black surface applicable in cryogenic systems than to make highly reflective surfaces. Experimental results on black surfaces like epoxy coatings, paints and thin films concerning the thermal radiative properties (emissivity and absorptivity) in the temperature range from 20 K to 300 K of the source of the thermal radiation are presented.
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Study of biodegradation of poly(hydroxy alkanoates).
Wurstová, Agáta ; Přikryl, Radek (referee) ; Obruča, Stanislav (advisor)
The master‘s thesis is focused on the study of biodegradation of polyhydroxyalkanoates, namely polymer polyhydroxybutyrate. The first part of the thesis is focused on the study of biodegradation of polyhydroxybutyrate in the form of crystalline granules of PHB and PHB films using selected species of microorganisms from bacteria, yeasts and fungi. As a representative of bacteria was chosen microorganism Delftia acidorovans, as yeast was selected Aureobasidium pullulans and Aspergillus fumigatus as fungi. PHB depolymerase activity was measured employing turbidemtiric method with suspension of PHB granules as substrate. The results showed that D. acidorovans can partially degrade PHB. On the contrary A. pullulans cannot effectively degrade PHB. The most significant degradation ability revealed A. fumigatus, which was able to degrade PHB completely. Extracellular enzymes excreted by these microorganisms when cultivated on PHB materials as sole carbon sources were analyzed by SDS-PAGE. The second part of the thesis deals with the biodegradation of PHB in the form of PHB film, PHB hardened foil and PHB Nanoul fabric using standard composting test. Semi-solid cultivation showed positive results. In the interval from 14 days to two months were all forms of the PHB completely biodegraded. With semi-solid cultivation was also studied biodegradation rate of the polyurethane elastomeric films which were modified by partial replacement of polyester polyol by PHB. The test samples were prepared using PHB from Sigma and the PHB samples prepared at the Faculty of chemistry VUT. Samples with different concentrations of the dispersed PHB (1 %, 5 % and 10 %) in the polyurethane were also object of the study. At the end of the cultivation (after 2 months) were measured mechanical properties in tension of the material, then efficiency of biodegradation by gravimetric analysis and modification of the material surface by microscopic analysis.
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Fotogenerace nosičů náboje v polymerních nanokompozitech
Pfleger, Jiří ; Pavlík, Martin ; Vohlídal, J.
Polymer nanocomposites seem to be promising systems for solar cell application with polythiophene acting as photosensitizer and charge transport medium. The electrophoretic deposition proved to be suitable method for preparation nanostructured core/shell functional layers. The simplicity, fast operation rate and the possibility of covering surfaces of irregular shape, as well as a good quality of prepared films are the major advantages of the method.
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Optimization of production of thin films of metallic materials
Čejka, Marek ; Kadlec, Michal (referee) ; Šubarda, Jiří (advisor)
The present thesis deals with optimization of the formation of thin layers of metallic materials. In the theoretical part was elaborated overview of the implementation of the formation of thin- film structures, particularly using vacuum techniques. Chemical and physical vapor deposition. They were described methods of pretreatment of thin layers. The findings were discussed methods of controlling the pre-treated surface, quality control and mutual adhesion of coating layers. In the experimental part of the pre-treatment methods were selected and applied to selected substrates. Pretreatments were evaluated using a control surface by wetting angles and by atomic force microscopy. Then, the metal structure formed of copper on the pretreated substrates. Implementation by means of magnetron sputtering. Adhesion layers was checked by testing the surface lattice method. The quality was observed by scanning electron microscopy. The results were used to design the technological process of making metal layers.
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Vliv dlouhodobě působící zvýšené teploty prostředí na vlastnosti povrchových úprav
Zavadil, Zbyněk
The thesis is focused on the effect of long-acting high temperature environment on the properties of transparent finishes lacquers. Samples of oak, beech and spruce wood are finished with transparent acrylic waterborne dispersion of a transparent two-component polyurethane coat. The samples coated with the surface film are exposed to temperature of 100 ° C for 28 days. Physical-mechanical properties of coating films are laboratory verified after seven days. The result of the thesis is the evaluation of measured values that are obtained by the methods ČSN and EN.
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