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Coating properties of cutting tools carbide
Doležalová, Petra ; Bumbálek, Bohumil (referee) ; Osička, Karel (advisor)
Diploma thesis is divided into two parts. The first part is focused on theoretical description of coating methods, on currently used coatings, their properties and it is also focused on description of methods, which are used for analyzing each property. The second part focuses on testing of coatings and analyzing of the values obtained from experiments. The aim of this thesis is then to compare the properties of the tested coatings.
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Reoxidation in steel
Kotásek, Petr ; Veselý, Pavel (referee) ; Šenberger, Jaroslav (advisor)
This work is about development and methodology verification of data collection which will be used in the research of the reoxidation in steel castings. To examine reoxidation rate will be measured oxygen activity in the furnace, in the ladle and in the mould. Next it will be evaluated the chemical structure of mould slag, the chemical changes of steel and measured the volume and the area of the casting defects. Each technique is briefly described by the principle of measurement and each method has the results which are analysed. In the conclusion the experiment is summarized and there are mentioned the observations from this experiment.
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Study of AlSi protective coating after degradation
Vítková, Gabriela ; Řičánková, Veronika (referee) ; Hutařová, Simona (advisor)
Materials used for high temperature applications works in a very aggressive environment (oxidation, hot corrosion, erosion, fatigue, creep). Demands on these materials are very high. Nickel-based superalloys show the certain stability in this environment. Improved resistance to oxidation and hot corrosion can be achieved by using protective layers such as diffusion barriers. This thesis is focused on changes of microstructure and properties of AlSi layer applied by „slurry“ method on nickel-based superalloy Inconel 713 LC, due to long-term thermal exposition at 800, 900 a 1000 °C.
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Analysis of usage hydrogen in power supply
Krček, Martin ; Ptáček, Michal (referee) ; Radil, Lukáš (advisor)
The work deals with harnessing the hydrogen in electricity production. It surveys hydrogen production, storage, transportation and its use as power source for fuel cells and combustion turbines. Characteristics of a hydrogen production electrolyzer were gauged in laboratory and its efficiency was evaluated.
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Elimination of degradation processes of metallic thin films
Danovič, Jakub ; Šubarda, Jiří (referee) ; Šimonová, Lucie (advisor)
This work deals with issues of thin films, their behaviour in different enviroments and protection of theese films against unwanted degradation processes. Metal thin films are made by special physical or chemical methods in the presence of vacuum. Deposition is performed on properly cleaned substrate made of different materials, for example glass, ceramics or another metal. Theese films degrades under the influence of moisture, heat and other. There are several types of films on different bases made to prevent thin films against degradation.
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Testing of polymeric materials under climatic conditions of Antarctica
Mičkal, Petr ; Sluková, Michaela (referee) ; Krmíček, Lukáš (advisor)
The bachelor's thesis generally deals with polymer materials and evaluates the possibility of testing their resistance to extreme climates of Antarctica. Described herein are various polymer materials, their characteristics, structure, properties and more thorough and detailed descriptions of selected polymers. The next section describes the basic types of degradation these polymers are exposed to, when facing the extreme conditions of the Antarctic climate. The practical part contains evaluations of tests made on the degraded polymer materials that were collected in Antarctica during the southern Antarctic season of 2013-2014 by Ing. Bc. Pavel Kapler, Ph.D, who is a superintendent at the Czech scientific station JG Mendel.
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Tribotechnická diagnostika prvonáplní motorového oleje z motorů osobních automobilů
Prokeš, David
The master thesis Tribotechnical diagnostics of first-fill engine oil from passenger car engines deals with the composition, production, distribution, wear and tear, specification of passenger car engine oils and their diagnostics and evaluation during use and wear. The research part of the thesis deals with the classification of lubricants and their brief description, classification of engine oils and a brief description of their manufacture. Subsequently, the basic concepts related to the above topic are described. The experimental part of the thesis deals with the methodology, material and actual measurement of selected parameters for the assessment of engine oil condition during engine break-in of new passenger cars. The selected indicators are the amount and morphology of particles, determination of the water content of engine oil, alkaline reserve, oxidation and additive content. The following diagnosis of the condition of the primary engine oil confirmed the assumption of a higher content of wear metals. An interesting result was the detection of higher oxidation rates in engine oils, which may be a consequence of long storage periods before the car is sold.
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Development of Electrochemical Thin-layer Degradation Cell for Oxidation Stress Testing of Active Pharmaceutical Ingredients
Šefčík, Martin ; Kubíčková, Anna (advisor) ; Coufal, Pavel (referee)
In this thesis, the oxidation conditions in a new electrochemical "thin-layer" flow-through cell for the study of the oxidative degradation of active pharmaceutical ingredients were optimized. In this field, it is an innovative approach to studying the oxidation properties of substances. The cell was manufactured using 3D printing technology. Oxidation was carried out in a two-electrode arrangement with a working boron-doped diamond electrode (BDDE) and an auxiliary stainless steel electrode. Optimization of conditions was performed using salicylic acid as a model active pharmaceutical ingredient. The electrochemical approach was used to degrade this active pharmaceutical ingredient by the required approximately 20% of the original amount in only 2.3 min. Thus, the degradation time was significantly reduced compared to the oxidative stability stress tests of active pharmaceutical ingredients commonly used today. Two major degradation products were observed, namely gentisic acid and 2,3-dihydroxybenzoic acid. The degradation products obtained by electrochemical oxidation and chemical oxidation using hydrogen peroxide are identical.
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Occurrence and removal of polluting organic substances during drinking water treatment
Prokopová, Michaela ; Pivokonský, Martin (advisor) ; Brányiková, Irena (referee) ; Kříženecká, Sylvie (referee)
Water sources pollution by natural organic substances and anthropogenic micropollutants is a global problem with a significant impact on water treatability and drinking water quality. One of the current topics is the proliferation of algal and cyanobacterial cells and the associated release of algal organic matter (AOM). The presence of AOM in drinking water sources can deteriorate the water's taste and odour or serve as precursors of disinfection by-products., especially in the case of a high proportion of the non-proteinaceous AOM, which is difficult to remove by conventional coagulation/flocculation. A part of this thesis is devoted to the composition and characterization of AOM, its chemical coagulation and electrocoagulation, and the assessment of the ozonation of the non-proteinaceous AOM during drinking water treatment. The second part of this thesis deals with the occurrence, characterization and removal of persistent anthropogenic substances, namely microplastics (MPs) and per- and polyfluoroalkyl substances (PFAS), during the drinking water treatment. Based on the results of ozonation of the non-proteinaceous AOM fraction (NP), it was found that ozonation caused a change in the surface charge, molecular weight or partial mineralization of NP, depending on ozonation conditions (O3 dose, pH...
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Development of voltammetric methods for detection of phytosterols on carbon-based electrodes
Zelenský, Michal ; Schwarzová, Karolina (advisor) ; Fischer, Jan (referee)
The aim of this diploma thesis was to develop an electrochemical method for three phytosterols, namely stigmasterol β-sitosterol and ergosterol using voltammetry techniques on glassy carbon electrode and boron doped diamond electrode. The work builds on previous results, where it was shown that the electrochemical oxidation of phytosterols requires perchloric acid in acetonitrile. When this acid is used, a dehydration reaction occurs. Calibration dependences were measured here for all phytosterols in an environment with a water content of 0.43%. The stability of the signal with increasing distilled water content was further investigated. Then the calibration dependences in the increased water content were measured again. If we want to use HPLC-type separation techniques, we must first find out how the phytosterols will behave in this environment, and therefore the signal stability on the buffer content was investigated. The buffers used were phosphate and acetate buffer. Subsequently, the concentration dependence was measured in an environment with a higher content of phosphate buffer. Furthermore, the possibility of detecting two phytosterols at once was investigated. Key words: dehydration, glassy carbon electrode, boron doped diamond electrode, oxidation, phytosterols, voltammetry
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