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Preparation and implementation of construction and technical survey of a building
Mezlík, Vojtěch ; Heřmánková, Věra (referee) ; Anton, Ondřej (advisor)
The subject of bachelor’s thesis is a structural-technical survey of a reinforced concrete frame structure. The theoretical part deals with the inspection of reinforced concrete structures, destructive and non-destructive diagnostic methods for the diagnosis of reinforced concrete structures, and the Czechoslovak architect Jaroslav Josef Polívka. The practical part conducts a structural-technical survey, focusing on the diagnosis of the reinforcement of selected structural elements and the determination of properties of the concrete. The reinforcement was determined using electromagnetic indicator Proceq Profometer 630 and the ground penetrating radar Hilti PS 1000 and verified by chiseled probes. The concrete strength class in the structure was estimated from core drills. In the conclusion, the condition of the structure is evaluated, and measures are proposed.
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Improvement of corrosion properties of MgAl-LDH coating on AZ31
Gromov, Egor ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
The subject of this bachelor thesis was the preparation and characterization (morphological and chemical) of layered double hydroxide (LDH) coatings with and without the addition of organic substances on AZ31 magnesium alloy treated by plasma electrolytic oxidation (PEO) to improve the corrosion resistance of the alloy. The samples were prepared at three different temperatures (100, 110 and 120 °C) for 4 or 24 h to determine the effect of the conditions on the quality of the LDH coating formed. For testing, samples were prepared with the addition of salicylic and tartaric acid. The corrosion resistance of the AZ31 alloy with coatings was described using the potentiodynamic polarization method and compared with the AZ31 alloy containing PEO coating. This was followed by a description of the morphological and elemental composition by SEM-EDS analysis, which confirmed the formation of MgAl-LDH. The best corrosion properties, according to the PDP method, were exhibited by the sample without the addition of acids, prepared at 100 °C for 4 h, but the greatest thickness of the LDH coating was obtained under conditions of 120 °C and 24 h. The samples with the addition of salicylic acid or tartaric acid showed poorer corrosion resistance compared to the LDH coatings prepared in the absence of organic substances.
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Verification of corrosion resistance of hyperduplex austenitic-ferritic stainless steel
Trkola, Ota ; Pernica, Vítězslav (referee) ; Kaněra, Miloš (advisor)
The bachelor's thesis deals with the corrosive resistance of a cast hyper duplex austenitic-ferritic steel. It is a prospective stainless steel that could be applied in foundry practice as a casting material in the future. The theoretical part contains an analysis of the principles of corrosion and the influence of the chemical composition on the structure and properties of steel. A significant part concerns duplex steels, especially their resistance to local types of corrosion expressed by the theoretical PRE number. The practical part of the work focuses on testing the corrosion resistance of hyper duplex steel using the corrosion test according to the ASTM G48 standard. The evaluation compares the corrosion attack with other alloys.
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Effect of EDTA on properties of layered double hydroxides deposited on Mg substrates
Tkadlec, Tomáš ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The subject of the bachelor's thesis was the preparation and characterization of MgAl LDH coatings on Mg substrates prepared by powder metallurgy with the aim of improving corrosion resistance. The coatings were prepared in a reaction mixture with various concentrations of EDTA. The corrosion resistance of the coated samples was analyzed using potentiodynamic measurements and compared with uncoated Mg. The sample prepared with a 5mM concentration of EDTA in the reaction mixture showed the best corrosion resistance. Higher concentrations of EDTA led to a deterioration of corrosion properties. The morphology and structure of the coatings and the elemental composition were described using electron microscopy and EDS analysis. Phase analysis was performed using X-ray diffraction (XRD). It was demonstrated that EDTA affects the structure of LDH coatings. The concentration of EDTA above 25mM in the reaction mixture results in the formation of Al(OH)3 coatings.
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Potential of AZ series magnesium alloys for ureteral stent manufacturing
Trnková, Zuzana ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
This master's thesis focuses on investigating the potential of magnesium alloys AZ31 and AZ91 for the production of ureteral stents. Potentiodynamic polarization (PDP) and electrical impedance spectroscopy (EIS) methods were used for electrochemical testing. Surface and microscopic analysis were conducted using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Immersion tests were used to characterize the corrosion solution and surface of AZ31 and AZ91 alloys. Fourier transform infrared spectroscopy (FTIR) with ATR module was used to determine the corrosion products on the surface of the alloys. The results showed that the AZ series alloys have potential for ureteral stent manufacturing, with AZ31 appearing to be more suitable than AZ91 as it provides more stable corrosion protection in the long term and the corrosion products do not form large particles that could lead to undesirable encrustation. Urea has also been shown to have a negligible impact on corrosion of AZ31 and AZ91 at lower concentrations, but at higher concentrations a significant impact on corrosion has been observed (especially in the case of AZ31).
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Use of acoustic emission technology to assess corrosion of materials
Procházka, Adam ; Vašíková, Simona (referee) ; Binar, Tomáš (advisor)
The thesis deals with the description of acoustic emission as a non-destructive testing method and its use in the detection of material corrosion. The first part describes the theoretical principles dealing with the explanation of what acoustic emission is, how it is defined according to the standard, what are the types of acoustic emission and how it is tested. It then discusses corrosion, the types of corrosive environments where corrosion occurs and the types of corrosion tests. It also describes where acoustic emission has been used in practice and what experiments it has been used for in terms of material monitoring. The next part of the paper describes the experiment of acoustic emission measurement on grey cast iron samples, describes the fabrication of the samples, the use of corrosion protectors, and the placement of the samples in a condensation chamber for continuous testing. The last part is the evaluation of the results .
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Preparation of yttrium-based coating to increase the corrosion resistance of AZ31 magnesium alloy
Kolařík, Václav ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
The subject of the bachelor thesis was the preparation and characterization (morphological and chemical) of coatings based on layered double hydroxides (LDH) with yttrium on AZ31 magnesium alloy to improve the corrosion resistance of the alloy. The coatings were prepared under mild and hydrothermal conditions and the synthesis was supported by thermodynamic assumptions. The corrosion resistance of the AZ31 alloy with coatings was described by potentiodynamic measurements and compared with the pure AZ31 alloy. This was followed by a description of the morphological and elemental composition through SEM-EDS analysis, and confirmation of the formation of the structures observed by this method was performed through FTIR analysis. The best coating prepared under mild conditions was a sample prepared at 90 °C for 24 h with a yttrium concentration of 0,05 M and under hydrothermal conditions it was a coating prepared at 120 °C for 30 h with a yttrium concentration of 0,075 M. SEM-EDS and FTIR analysis did not show the formation of MgY-LDH but the formation of Mg(OH)2. Yttrium was minorly represented in the coatings where it could be present, e.g. as Y(OH)3. Yttrium was shown to have a positive effect on the preparation of the coatings compared to the sample prepared without yttrium under the same reaction conditions.
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Surface cleaning of archaeological objects by plasma generated in water solutions
Tihonová, Jitka ; Grossmannová, Hana (referee) ; Krčma, František (advisor)
This bachelor thesis is focused on the plasma surface treatment of historical ceramics by low temperature electrical discharges in water solution. Four samples were chosen - two of the Lusatian Urnfields Culture and two of Anabaptist Faience. The treatment was done at minimum power of the power supply. Stainless steel electrode and a specially designed electrode system with wolfram wire in the quartz glass capillary were used for generation of discharge using an audio frequency power supply. Elemental analysis by scanning electron microscopy (SEM) was done before and after the treatment and values were compared with the elemental analysis of material’s core. Samples of the Lusatian Urnfields Culture were successfully treated without any surface damage. The first one of samples of Anabaptist Faience was damaged. The experiment was repeated on the glass to determine the cause. It was find out that damage was probably caused by thermal stress. The second one of Anabaptist Faience was already treated without damage. Next research will be focused on determining specific conditions of the power supply, modification of water solution and modification of sample’s surface for the most efficient ancient ceramics cleaning.
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Determination of climatic factor on the degradation of various solar cells types
Peroutka, Tomáš ; Jandová, Kristýna (referee) ; Vaněk, Jiří (advisor)
In this work are discussed photovoltaic cells. There are also discussed basic concepts of radiation source for solar cells. Also mentioned the issue of semiconductors and even the history and evolution of the solar cells. A large part deals with possibilities of photovoltaic cells degradation. In one chapter is an attempt to bring some types of photovoltaic cells and a description of the production of these modules.The practical part deals with photovoltaic modules degradation and its evaluation. Following part compares measured values with the values provided by producer of photovoltaic modules.
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Evaluation of electrochemical characteristics of AZ61 wrought magnesium alloy
Kotek, Jakub ; Minda, Jozef (referee) ; Fintová, Stanislava (advisor)
This work is focused on evaluation the electrochemical characteristics of AZ61 wrought magnesium alloy. Electrochemical impedance spectroscopy and potentiodynamic tests were used to evaluate the electrochemical characteristic of the alloy. Values of polarization resistance were determined with electrochemical impedance spectroscopy. Values of corrosion potential and corrosion current density were determined with potentiodynamic tests. Sodium chloride solution at a concentration of 0.1 mol·dm-3 was used as a corrosion medium. Outcome of this work is to estimate an influence of fabrication, chemical composition and surface treatment on the corrosion properties of magnesium alloy.
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