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Influence of alloying elements on the solubility of titanium in magnesium alloys
Matocha, Martin ; Buchtík, Martin (referee) ; Březina, Matěj (advisor)
This bachelor's thesis examines the influence of alloying elements on the solubility of titanium in magnesium alloys. In the theoretical part, a literature review was conducted on the topics of the creation, composition, processing, and brief analysis possibilities of magnesium alloys, with an emphasis on the potential for alloying magnesium alloys with titanium. The experimental part focused on the preparation of systems with various compositions to achieve the integration of titanium into the magnesium alloy. After preparation of the samples of the given systems, their analysis was performed using SEM/EDS and XRD. Based on the ongoing results of the samples analysis, efforts were made to optimize the holding time of the samples of the given system at a temperature of 905°C. It was found that during the stabilization of the modification of titanium, it is possible to achieve mixing of titanium, zinc, and magnesium. The condition for the formation of the modification of titanium is the highest possible temperature allowed by the system. However, the temperature must exceed at least 881°C. The stability of the modification of titanium is also supported by the absence of alloying elements that promote the stability of the modification of titanium. The mixture of elements in the aforementioned system has not yet been described in the scientific literature.
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Model diffusion experiment in alloys
Valúch, Adam ; Doubrava, Marek (referee) ; Kičmerová, Dina (advisor)
This bachelor's thesis deals with the process of diffusion in alloys, for a better understanding of the properties and microstructure. In the theoretical part, the nature of diffusion is described, brass and copper are used for different diffusion rates at different temperatures and times. In the experimental part, methods such as annealing in a vacuum furnace, polishing, and grinding are used. With subsequent observation under a SM, SEM microscope. The main goals were to prove the Kirkendall phenomenon and the previously mentioned microstructure and thickness of the diffusion layer.
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Analysis of hazardous metals in rPET granulate
Souček, Elena ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
Production of polymer products has increased rapidly in recent decades. Especially in food industry as a packaging it gained a dominant position when it replaced previously used materials. Due to the direct risk for human health it is necessary to be careful and pay attention to their composition. It is also necessary to develop methods to properly recycle and reuse already used material, not only produce new products. This thesis deals with the study of the content of risk elements in PET regranulate. The samples were completely decomposed by microwave radiation in an environment of concentrated sulfuric and nitric acid. They were subsequently analyzed by atomic absorption spectrometry (AAS). Flame atomization technique (FAAS) was used to determine Sb and Zn and electrothermal atomization (ETAAS) to determine Cd, Cr, Pb, Cu and Ni. This method was also used to study migration of antimony from samples to food simulant under different conditions (temperature, pH). This thesis follows up on the thesis of Mrs. Kryštofová who studied recycled PET flakes.
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Study of the content of risk elements in river sediments of the Váh River
Držíková, Klára ; Zlámalová Gargošová, Helena (referee) ; Komendová, Renata (advisor)
This bachelor thesis deals with the analysis of selected heavy metals in the river sediment of the Váh River. The elements were selected based on their relatively frequent occurrence and adverse effects on humans, fauna, and flora. Also due to their ability of good accumulation and persistence in sediments. The selected elements have a chalcophile character, which plays a significant role in the occurrence of the elements at the sampling sites. The analysis of the collected sediment samples was carried out using atomic absorption spectroscopy. The highest concentration of zinc (386.58 mg/kg), followed by copper (57.67 mg/kg), lead (42.24 mg/kg), and the lowest concentration of mercury (0.332 mg/kg) was measured in the sediments. Sediments are used in agriculture and forestry to improve soil properties. Their application to soils is regulated by Slovak legislation, which sets limit values for risk elements in the concerned sediment and soil. These established limits were not exceeded in any of the sediment samples.
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The study of vertical mobility of heavy metals and their transfer to mushrooms
Jurnečka, Roman ; Doležalová Weissmannová, Helena (referee) ; Komendová, Renata (advisor)
This bachelor thesis deals with the issue of contamination of forest soils and edible mushrooms with lead, cadmium, copper and zinc in the Jeseníky Mountains, specifically in the Domašov and Vápenná forests. Sampling took place at 12 localities, divided into spruce and beech stands. Atomic absorption spectrometry AAS ContrAA 800D was chosen to determine the content of selected heavy metals. Based on the measured values of the concentrations of the studied metals and other soil properties, dependences were created to determine the vertical mobility of selected metals in the soil profile. Vertical mobility depends on the physico-chemical properties of the soil (pH, C and S content). The dependence of the content of selected heavy metals in the soil on the pH value of the soil was found. In the case of lead, the sorption capacity of the soil organic component was confirmed. The risk and above-limit content of Pb, Cd and Cu was found on the yellow-boletus mushroom. Cadmium shows the highest bioavailability. Lead was evaluated as the element with the lowest mobility.
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Surface Modification of Zinc Alloys
Kinc, Marek ; Foral, Karel (referee) ; Molliková, Eva (advisor)
The object of this bachelor’s thesis is to create a research in field of zinc alloys. In the first part, there are outlined production of pure zinc with a different methods and briefly described the treatment of waste. The next are described the zinc alloys and their properties and outline the ways of die casting. The end of this thesis is focused on methods of finishing the surfaces.
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Zn and Mg based bulk materials for biomedical applications
Ryšťák, Jaroslav ; Fintová, Stanislava (referee) ; Doležal, Pavel (advisor)
Topic of the diploma thesis is Zn-Mg bulk material preparation by powder mixtures sintering at hot pressing. Structure, porosity and physically mechanical properties of prepared bulk materials were evaluated. Obtained results and their interpretation were served as feedback for following optimization of individual processing parameters of bulk materials preparation. Solution of diploma thesis is focused on study and control of processes during bulk material preparation and processes description from physical-chemical point of view with respect to structure creation and final material properties.
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The Study of ZnO Crystal Growth in Supersaturated Alkaline Solution
Bannert, Tomáš ; Máca, Josef (referee) ; Chladil, Ladislav (advisor)
This thesis deals with the study of growth of zinc oxide crystals from supersaturated solutions using a scanning electron microscope and XRD methods. The work is divided into a theoretical and an experimental part. The theoretical part analyses issues related to the principle of operation of electrochemical cells with an emphasis on Ni-Zn batteries and phenomena limiting the life and efficiency of Ni-Zn batteries with a focus on phenomena that affect precipitation processes of zinc oxide crystals. It also analyses and compares the appropriateness of the methods that have been used to study the growth of the prepared zinc oxide crystals. The experimental part describes the preparation of a supersaturated solution, the process of each analysis and its evaluation. The results of each method are compared with the theoretical assumptions and among themselves. The experimental part also contains a chapter dealing with the design of in situ X-ray diffraction analysis methods of the obtained zinc oxide crystals.
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Preparation and properties of porous zinc material
Ryšťák, Jaroslav ; Fintová, Stanislava (referee) ; Doležal, Pavel (advisor)
Bachelor thesis is focused on preparation of bulk material prepared from zinc powder by cold pressing followed by sintering. Topic of the work includes characterization of prepared material depending on the choice of the compaction process conditions. Bulk material is characterized by physical-mechanical tests, structure and porosity. Thesis solving and focuses on study and control of processes during bulk material preparation and description of the processes from physically-chemical point of view of the structure creation and final material properties.
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