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Diagnostics of reinforced concrete structures
Nápravník, Petr ; Komárková, Tereza (referee) ; Láník, Jaromír (advisor)
This thesis deals with the structural-technical survey of beam bridge no. 204c - M1, located in Bystřice pod Hostýnem. The theoretical part of the thesis is devoted to general characteristics of bridges, load capacity of bridges, beam bridges, concrete reinforcement, concrete, diagnosis of reinforced concrete structures, and laboratory evaluation. The practical part deals with carrying out a structural-technical survey on the bridge mentioned above, its evaluation and assessment, recalculation of the load capacity, and design of the necessary rehabilitation to maintain the functionality of the bridge.
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Study of phytic acid-based organic conversion coatings on magnesium alloys
Zbíral, Roman ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
This thesis deals with organic conversion coatings based on phytic acid, on the magnesium alloys. In theoretical part it deals with corrosion properties of magnesium and magnesium alloys, usage of magnesium alloys for biomedicine applications. There are also summarized information’s about usage of phytic acid, it’s reactions with magnesium and magnesium alloys. At the end of theoretical part is search about phytic acid conversion coatings deposited on magnesium alloys. There are studied optimal conditions for application of phytic acid coatings such as pH, concentration, time of deposition, etc. Based on the knowledge from the theoretical part, a layer based on phytic acid was deposited on the surface of Mg alloy AZ31. The coating was evaluated in the experimental part in terms of its morphology and structure, chemical and corrosion behaviour. Scanning electron microscope (SEM) images showed the presence of microcracks in the dried coating. The chemical nature of the phytic acid-based conversion coating was investigated by energy dispersive spectroscopy (EDS) techniques in combination with Fourier transform infrared spectroscopy (FTIR). The electrochemical corrosion behaviour of Mg alloy AZ31 and coated Mg alloy was investigated by potentiodynamic polarization in Hank's solutions. Based on the obtained values of the corrosion potential and the corrosion current density, it can be stated that the applied layer of the conversion coating leads to an improvement of the corrosion properties. From the results of SEM analysis of samples after exposure in a corrosive environment, it was found that during potentiodynamic measurements no significant manifestation of corrosion attack was observed in coated samples, as was the case with Mg alloy AZ31.
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Low pressure plasma application for the surface cleaning of archaeological objects
Bubnová, Kateřina ; Grossmannová, Hana (referee) ; Krčma, František (advisor)
This diploma thesis builds on my bachelor thesis, which was focused on the application of low-pressure hydrogen plasma and argon-hydrogen plasma on layers of corrosion products. According to results of the experiments, an appropriate temperature for plasma chemical treatment of lead samples was detected. However, the process of corrosion removal through plasma chemical treatment needs to be further optimized to prevent potential damage to the original historical artefacts. Optimization of the treatment process is therefore the main subject of this work’s research. The model samples with artificial corrosion layers with dual composition were prepared. These samples were put to desiccator with sand and organic acid. The samples corroded in environment of acetic acid or formic acid with the aim of creating the corrosion, which would be at least partially simulated with corrosion on the original artefacts. The process of corrosion lasted for eleven months. After that, the samples were dried out under reduced pressure, put to the protecting foil with humid and oxygen absorbers. In contrast with my bachelor thesis where the continuous regime was chosen for the treatment, the pulse regime with three different condition settings is used. Process of experiment was monitored by OES, surface of samples was analyzed by SEM, EDX, XRD methods. Results from experiments with model samples were used for treatment of original artefacts with missing documentation, so their eventual damaging was acceptable.
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Fluoride conversion coatings on magnesium materials
Staněk, Jan ; Wasserbauer, Jaromír (referee) ; Březina, Matěj (advisor)
This bachelor thesis deals with the topic of corrosion protection of magnesium materials by conversion coatings. The aim is to characterize and compare properties of fluoride conversion coatings formed on wrought magnesium sample and magnesium sample prepared by powder metallurgy. Basic knowledge of pure magnesium, magnesium alloys, powder metallurgy, corrosion, and protection against it are described in the theoretical part. Recent results of corrosion protection by fluoride conversion coatings on magnesium materials are summarised in the recherché part. The experimental part is focused on preparation of fluoride conversion coatings on each type of sample by immersion in Na[BF4] molten salt and by dipping in hydrofluoric acid. Surface morphology and composition of coatings were characterized by EDS analysis and corrosion protection was evaluated by potentiodynamic measurements.
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Materials For Biodegradable Bones Based On Fe
Hrabovský, Jan
The thesis deals with biodegradable bone implants which must have good mechanicalproperties and also good compatibility with the human body. The thesis contains literary research inthe area of bone physiology, biogenic materials and implants for the human body. The thesis focueson the selection of suitable materials for biogenic implants.
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Materials For Biodegradable Bones Based On Fe
Tkáčová, Tereza ; Hrabovský, Jan
The thesis deals with biodegradable bone implants which must have good mechanical properties and also good compatibility with the human body. The thesis contains literary research in the area of bone physiology, biogenic materials and implants for the human body. The thesis focues on the selection of suitable materials for biogenic implants.
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Effect of hyaluronic acid on the corrosion of AZ31 magnesium alloy
Holubářová, Michaela ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
Magnesium and its alloys are interesting materials due to their many physical properties. They have considerable potential, especially in medical applications, where they can serve as a material for the production of orthopedic and cardiovascular implants. The disadvantage of these materials is their sensitivity to corrosion. As a result, it is necessary to know the corrosive properties of magnesium and its alloys in contact with substances that occur in the human body. Hyaluronan is a polysaccharide that is naturally present in the human body and can interact with implants. This master's thesis deals with the influence of low molecular weight (80–130 kDa) and high molecular weight (1 500–1 750 kDa) hyaluronan on the corrosion properties of magnesium alloy AZ31 in the environment of two simulated physiological solutions (0,9 % NaCl and synovial fluid). Potentiodynamic polarization (PD) and electrical impedance spectroscopy (EIS) were used for electrochemical tests. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to reveal the chemical composition of the corrosion products and the surface morphology after corrosion.
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Workplace for measuring electrochemical potential of metals
Cápal, David ; Kazda, Tomáš (referee) ; Libich, Jiří (advisor)
This bachelor's thesis describes the issues related to corrosion in electrical engineering. Thesis describes corrosion itself, historical mentions and causes. It also deals in deatail with electrochemical corrosion and the behavior of ions at the electrode-electrolyte interface together with the redox processes that accompany them. This thesis describes the origin and use of these electrochemical reactions as a way of creating electrochemical potential in liquid electrolytes at the metal-electrolyte interface. Thesis also describes measuring methods and evaluation of measured results using polarization curves and Tafel diagrams.
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Design of oscillating head for surface welding of Inconel 625
Franc, Tadeáš ; Slaný, Martin (referee) ; Zouhar, Jan (advisor)
This diploma thesis deals with the structural design and production of a oscillating head for surface welding of a protective layer of Inconel® 625 superalloy on membrane walls. The design is preceded by a research for possible variants of the solution. Of the two designs, one was successfully manufactured and assembled, and incentives for future improvements were set. For easy optimization and testing of the device, an oscillating motion program was created in the LinMoT Talk 6.9 software. The production costs for the manufactured equipment were then calculated and the recommended selling price was determined, based on a general calculation formula. The result of the project is a functional device, a proposal for its control and a technical - economic evaluation of the production process.
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Use of cold kinetic deposition technology on materials used in electrical engineering
Sámel, Maroš ; Zimáková, Jana (referee) ; Binar, Tomáš (advisor)
The purpose of this diploma thesis is to get a better understanding of cold kinetic deposition (cold spray), principles of functioning of this method followed by an evaluation of advantages and disadvantages of cold spray and its comparison to conventional thermal methods and a simple summary of the practical use of cold spray with respect to different materials. Next there is a summary of the properties and uses of frequently applied metals in electrical engineering, aluminium and copper, description of metal corrosion and an understanding of the diagnostic method of acoustic emission. In the practical part, a sample with copper cold spray coating on aluminium substrate was created. Following, this sample was split for corrosion tests, where the split samples were exposed to a corrosive environment for different times of exposure. The extent of corrosion degradation of the samples was evaluated by acoustic emission and metallographic analysis for corrosion-loaded samples for 100, 200 and 300 hours. In the end, an illustrative design of the application of the cold spray technology was created.
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