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Optimizing of Polymer Surface Treatment for Microscopic Examination
Horská, Pavlína ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Supramolecular structure of eight commercial types of iPP, its blends with poly(L-lactide) (PP-PLLA) and copolymers with ethylene-propylene rubber (PP-EPR) together with four types of polyethylene (LDPE, HDPE) was uncovered and observed in this work. The spherulitic structure of iPP and PE homopolymers and PP copolymers was uncovered by etching of six different solutions of mineral acids with KMnO4 and by dissolution in four selected solvents. The latter was found to be ineffective. The structure of PP-PLLA blends was uncovered only after recrystallization (the change of structure by annealing and cooling rate). The uncovered crystalline structure was observed directly by confocal laser scanning microscope (CLSM) and SEM. Crystallinity together with a size distribution of crystallites was determined by DSC. It was proved that spherulitic supramolecular structure was easy to uncover by chemical etching only for molded samples and for fracture surfaces of injected samples. The efficiency of etchants varied but, generally, the samples with high degree of crystallinity were etched earlier. The etchants containing nitric acid and high content of sulphuric acid uncovered fine details of shperulites with respect to mixtures containing orthophosporic acid. It was also observed that not only the etchant (especially with nitric acid) itself but also its vapors were effective. The structure was revealed later but the appearance was plastic (3D) and the structure was very fine. The supramolecular structure of PP-PLLA blends differed with amount of each component. The ethylene-rubber phase came forth with increasing time of etching while PP spherulites disappeared in PP-EPR samples. CLSM was shown to be very good tool for observing supramolecular structure of studied samples with respect to SEM, which was proved to be entirely unsuitable for polyolefines. DSC is recommended to be performe before uncovering supramolecular structure for basic information about proportion of amorphous/crystalline phase and size of crystallites.
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Optimization of PCB Process Developing and Etching
Nerušil, Petr ; Zatloukal, Miroslav (referee) ; Starý, Jiří (advisor)
Bachelor´s thesis deals with photoresist developing and copper etching – these ones are the key operations in the double layer PCB production realised with pattern plating subtractive technique. Test pattern and a schematic diagram of the technological process for quality control in the practical part. Main part of this thesis is focused to operations of photoresist developing and to inspection and evaluation of photoresist width changes on test pattern during developing and etching including copper etch factor.
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Nanoelectrodes for biophysical measurements
Márik, Marian ; Hrdý, Radim (referee) ; Hubálek, Jaromír (advisor)
The aim of the project is formation of nanoelectrodes on the silicon wafer surface by thin-film techniques combined with lithography and nanotechniques developed in LabSensNano. Project is engaged in lithography and in preparation of silicon wafers. Furthermore is proposed a brief proposal of electrodes, proposal of realization and current state of the experiment.
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Analysis of Fingerprint Spoofs Created from Mold Done by Etching Technique
Tilgner, Jan ; Sakin, Martin (referee) ; Kanich, Ondřej (advisor)
This work aims to analyse fingerprint spoofs from mold created by etching. Mold will be created using the technique used to create printed circuit board. After that spoof will be cast using liquid latex and then scanned. Created spoofs will then be compared to their original image. Algorithm to evaluate these spoofs is designed and implemented. The algorithm works by comparing pairs of minutiae from each fingerprint if they are similar. This alghoritm will be tested on database of fingerprint spoofs and the results will be compared to existing software results. Spoofs created by this technique had poor quality and minutiae did not match the original fingerprint.
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Properties of electrode materials for alcaline accumulators
Fusek, Petr ; Vrbický, Jiří (referee) ; Sedlaříková, Marie (advisor)
The Bachelor´s Thesis is aimed at the problematic of the binders, that effects the features of the positive electrode of alcalic accumulators. The additive used on nickel´s electrode was cobalt. In the practical part of this thesis there is described a process for etching the nickel electrode and the following electrodepositions applied on these electrodes. Measurements of different concentrations of nickel and cobalt were examined and analysed in the graphs which are part of this thesis. There have been made comments of these graphs and the conclusions and observations as well.
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Exposure equipment for PCBs
Fiala, Matouš ; Čech, Ondřej (referee) ; Vyroubal, Petr (advisor)
The Master's thesis deals with the fabrication of printed circuit board exposure devices, including establishing a theoretical basis for understanding the PCB production process, using lithography over a liquid crystal panel to create a motif. The thesis includes the creation of a CAD model of the device, including a UV source and then thermal simulation of the cooling of the device. The fabrication of the device also involved the creation of a custom motherboard that integrates all of the electronic components. The main result of this work is an assembled functional device with a unique LCD layer arrangement that allows reliable exposure of dual-layer PCBs, which is supported by testing. The most comprehensive part of this thesis deals with the development of a complete software platform, consisting of an application running on the microcomputer of the exposure device and a multi-platform application through which the device is wirelessly controlled.
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GaN deposition on a tungsten substrate
Pikna, Štěpán ; Piastek, Jakub (referee) ; Čalkovský, Vojtěch (advisor)
This bachelor thesis is focused on deposition of GaN nanocrystals on the etched tungsten tips. Motivation was to prepare these GaN structures on the Schottky cathode made by company ThermoFisher Scientific and measure its field emission. In the theoretical part of the thesis GaN and tungsten field emission properties are introduced. The experimental part begins with tungsten tip etching optimalization, where the right values for best tips are temperature 20 °C, depth of the tip 2,5 mm and solution NaOH used. Further the gallium structures were prepared on these tips using molecular beam epitaxy (MBE). The right temperature to prepare GaN nanocrystals was determined as 200 °C. The deposition of gallium was set to 2 hours and following nitridation was 3 hours. Finally, the field emission from GaN prepared on copper foil with graphene was measured and compared with other experiments.
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Preparation and characterization of highly hydrophobic coatings on AZ 91 magnesium alloy
Šomanová, Pavlína ; Hasoňová, Michaela (referee) ; Doskočil, Leoš (advisor)
Magnesium and its alloys have many interesting properties and thanks to them it can be used in many applications (transport industry, medicine etc.). Disadvantage of these materials is their high corrosion rate. For this reason, there is an effort to achieve high corrosion resistance through different modifications of magnesium and its alloys. In recent years the superhydrophobization of the surface seem to be an attractive solution for this question. This type surface modification minimalize contact between the surface and water. In this diploma thesis the superhydrophobic surface was created on the magnesium alloy AZ91. The first step included pretreatment of AZ91 surface by etching in solution of SnCl2 or ZnCl2. Next step was superhydrophobization in the ethanolic solution of stearic acid. The surface morphology and elemental analysis of the superhydrophobic coating were explored by use of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The adhesion properties of the coating on the AZ91 were analysed by means of scratching test. Contact and sliding angles were measured for superhydrophobic coatings. Electrochemical characterization of the coatings was determined using potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS). Finally, the analysis of composition and the functional groups was made using Fourier-transform infrared spectroscopy (FTIR) and the phase composition analysis was performed using X-ray diffraction (XRD). The results show that the coatings prepared by etching did not lead to good corrosion properties, even though the value of contact angle was about 150 °. The reduction of corrosion resistance could be caused by not obtaining required surface morphology or insufficient binding of stearic acid in the form of stearate to the sample surface.
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Analysis of Fingerprint Spoofs Created from Mold Done by Etching Technique
Tilgner, Jan ; Sakin, Martin (referee) ; Kanich, Ondřej (advisor)
This work aims to analyse fingerprint spoofs from mold created by etching. Mold will be created using the technique used to create printed circuit board. After that spoof will be cast using liquid latex and then scanned. Created spoofs will then be compared to their original image. Algorithm to evaluate these spoofs is designed and implemented. The algorithm works by comparing pairs of minutiae from each fingerprint if they are similar. This alghoritm will be tested on database of fingerprint spoofs and the results will be compared to existing software results. Spoofs created by this technique had poor quality and minutiae did not match the original fingerprint.
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