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Influence of nanoparticles on the properties of electroinsulating materials
Sedláček, Michal ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with influence nanoparticles, as fillers of polymer, to electrical properties dielectric composite materials. Addition of just a few weight percent of nonofillers has profound impact on the physical, chemical, mechanical and electrical properties orf polymer. Simultaneously is focused on production and diagnostics by the relaxation spectroscopy and measure internal resistance. Examination material is epoxy resin TSA 220S filled Al2O3 and SiO2 nanoparticles.
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Analysis of composite system with different filler ratio
Mydlář, Marek ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
This master’s thesis applies dielectric relaxation spectroscopy to analyse impact of climatic changes on dielectric properties of composite material samples (TSA 220S varnish combined with 60.030 mica). Experiments aim to analyse effect of mica composite mass ratio (0, 4, 8 and 16 % of mica), relative humidity (0, 33, 55, 65, 75 and 95 %) and temperature (23, 30, 40 and 50 C) on complex permitivity as a function of frequency.
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Modification of electroinsulating varnish with ground mica
Drápal, Aleš ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
This master's thesis focuses on composite systems based on varnish combined with different filler ratios of micronized mica. The aim is to analyse impact of the filler on dielectric properties of the varnish, i.e. relative permittivity and loss factor as functions of frequency as well as charging and discharging currents as functions of time. Dielectric mixture formulas are applied on relative permittivity values. Calculated and measured values are compared.
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Degradation test of polymer material in the high electric fields
Martynek, Aleš ; Křivík, Petr (referee) ; Vaněk, Jiří (advisor)
This document includes methods of testing and measuring of the protective layers used in solar panels with crystallic solar cells. The main emphasis here is placed on the degradation of these materials due to exposure to strong electric field. Main point of diploma thesis is evovle an experimental workplace for electric aging of dielectric materials and monitor changes of material properties. Final knowledges are then analysed with the climate degradation tests. Tested samples were prepared in cooperation with Solartec s.r.o.
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Wire electrical discharge machining
Gvizd, Michal ; Mouralová, Kateřina (referee) ; Osička, Karel (advisor)
Bachelor thesis elaborated during the bachelor study discusses the electrical discharge cutting of materials with a wire electrode and its usage in industry. The thesis is divided into two fundamental parts –the theoretical and the experimental one. The theoretical part describes the historical development, explains the basic principle and fundamentals of this unconventional way of machining with the definition of methods using this technology. The thesis is focused on the electrical discharge machining, thus gougers are mentioned only peripherally. Afterwards, the wire electrodes used, main machine parts, cutting conditions and advantages of this technology are analyzed in detail. The experimental part deals with the evaluation of cutting surfaces of the sample components with respect to dimension accuracy, surface quality and describes factors which affect these characteristics. The emphasis is put on the machining of the tool steel. Conclusion discusses the analysis of the assembled measurements, their technological/economical analysis and outlines the direction of development in the possibilities of this unconventional technology of material separation.
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Optické a elektrické charakteristiky koplanárního povrchového bariérového výboje v dusíku
Šimek, Milan ; Homola, T.
We inspected basic electrical and optical characteristics of dielectric coplanar surface barrier discharge (DCSBD) driven by AC high voltage at atmospheric pressure in high purity nitrogen. Voltage and current traces together with intensity evolution of most important emissions were registered with high time resolution in the UV-vis-NIR spectral range and for various densities of micro-discharges generated on the DCSBD surface. It comes out that most intense emissions are produced by a) energetic electrons through direct electron impact excitation/ionisation of N2 molecule and b) N2(A) metastable species through N2(A)+ N2(A) energy pooling and N2(A)+NO resonant energy transfer processes.
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Účinnost generace ozónu v koplanárním povrchovém bariérovém výboji v syntetickém vzduchu
Šimek, Milan ; Homola, T.
Efficiency of ozone formation by Dielectric Coplanar Surface Barrier Discharge driven in atmospheric-pressure, dry synthetic air was examined in a wide range of applied energy densities (0.01-1 Wh/l). Applied energy density was controlled by combining appropriately dissipated discharge power with airflow rate (5 – 50 l min-1). The O3 concentration was monitored outside the discharge chamber by means of non-dispersive UV photometric O3 analyzer. From the ozone production concentration measurements, we evaluated ozone production and yield. The ozone concentration, production and yield reached 800ppm, 5 g/h and 40 g/kWh, respectively.
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