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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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Study of lithium encapsulation in porous membrane using ion and neutron beams
Ceccio, Giovanni ; Cannavó, Antonino ; Horák, Pavel ; Torrisi, Alfio ; Tomandl, Ivo ; Hnatowicz, Vladimír ; Vacík, Jiří
Ion track-etched membranes are porous systems obtained by etching of the latent ion tracks using a suitable etchant solution. In this work, control of the pores' spatial profiles and dimensions in PET polymers was achieved by varying etching temperature and etching time. For determination of the pores' shape, Ion Transmission Spectroscopy technique was employed. In this method, alterations of the energy loss spectra of the transmitted ions reflect alterations in the material density of the porous foils, as well as alterations of their thickness. Simulation code, developed by the team, allowed the tomographic study of the ion track 3D geometry and its evolution during chemical etching. From the doping of porous membranes with lithium-based solution and its analysis by Thermal Neutron Depth Profiling method, the ability of porous PET membranes to encapsulate nano-sized material was also inspected. The study is important for various applications, e.g., for catalysis, active agents, biosensors, etc.
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CREATION OF NANOSTRUCTURES ON SURFACES OF SOLID MATTER USING HYBRID METHODS
Rudolfová, Zdena ; Mikulík, Petr (referee) ; Horová, Ivana (referee) ; Kolíbal, Miroslav (advisor)
This thesis deals with the study of GaAs surface properties and with methodology of metal (mainly gold) nanoparticles deposition on GaAs substrate. GaAs has complicated surface oxides structure, which are very reactive when exposed to various chemicals (both acids and alkalines) and therefore they change GaAs surface properties. That is why the study of this properties is crucial for understanding of GaAs surface reactions on metal particles colloidal solution, from which the nanoparticles are deposited on the surface. The possibilites of GaAs surface etching and passivation are discussed. These should lead to surface stability enhancement during colloidal nanoparticles deposition. There was also studied the influence of adhesive polymer monolayer grown on GaAs substrate to the amount of nanoparticles deposited to the surface after substrate immersion into colloidal solution. This thesis concentrates on analyzing of methods, how the gold colloidal nanoparticles can be deposited selectivelly, only to defined areas. The areas were defined using charged particle beam.
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Local electrical conductivity measurements in AFM tapping mode
Dao, Radek ; Konečný, Martin (referee) ; Pavera, Michal (advisor)
This bachelor thesis is concerned about the development of a probe for local electrical conductivity measurements in tapping mode Atomic Force Microscopy. The teoretical part gives a short overview of Scanning Probe Microscopy techniques, with the focus being on Conductivity Atomic Force Microscopy. Furthermore, the measuring regime in which the probe operates is described here, as well as the basic component of the probe, the quartz tuning fork. The experimental part follows the iterative development process, and contains a chapter dedicated to making of very sharp tips. The final chapters describe the preparation of test samples, which were used to prove the functionality of the probe and the measurement of local electrical conductivity itself.
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Preparation and testing of SNOM probes
Bobek, Juraj ; Pavera, Michal (referee) ; Spousta, Jiří (advisor)
The area of research that deals with surface modification and preparation of nanostructures is still very unexplored. And only a little contribution to this field is discussed in this bachelor thesis. Its goal is to manufacture and to test a probe made off hollow optical fibre that is used in Scanning Probe Microscopy. Optical fibre parameters in combination with proper and unique techniques allow the breakthrough off very interesting applications. It's worth mentioning the gas injection in the proximity of the surface of a sample (GIS) and thus its modification by use of electrons (FEBID), ions (FIBID) or laser beams.
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Master B with the Die from the collection of National Gallery in Prague
Veselá, Markéta ; Zlatohlávek, Martin (advisor) ; Konečný, Lubomír (referee)
The aim of this essay is an assessment of an anonymous engraver's work from the early 16th century whose monogram is a cube with a letter B. The essay is divided into two separate main units. The first enclosed unit includes texts helping us to create a partial picture of the Master's life. There are information dealing with a cultural environment and a technological development of the graphic art in the times of the Master's existence. The second unit is a char- acterization and a detailed analysis of selected pieces of work with an accent on the technologi- cal aspect of the prints. The creation of the Master's B of the Die life story was very difficult considering the lack of the literature. After a thorough search in libraries and on the internet not even one continu- ous text concerning directly this artist has been found. Incomplete information have been found only in collected encyclopaedias about art. For drawing-up at least a short life story accessible information about cultural environment of the then humanistic society have been used which are composed in a separate chapter. The next separate part of a lesser extent is interested in edi- tors co-operating in the Master's B of the Die environment and participating on the production of his graphics. Together with the analysis of the...
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Production and characterization of nanoporous alumina membranes
Šimik, Milan ; Márik, Marian (referee) ; Kynclová, Hana (advisor)
The Bachelor thesis mostly deals with manufacturing of membranes with anodic oxidation of aluminium in different conditions. In theoretical part are studied processes leading to creating of porous alumina and methods of measuring permeability of membranes. Practical part is aimed on manufacturing porous alumina with different conditions, which are afterwards suffused into form and diffuse characterized. Measured parametres are interpreted and compared with each other.
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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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