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Assessment of corrosion degradation in materials
Plichta, Lukáš ; Zimáková, Jana (referee) ; Binar, Tomáš (advisor)
The work describes the principle of degradation of corrosion in materials, specifically metals and their alloys. Corrosion is divided into several aspects. The fundamental division according to its origin divides this phenomenon into chemical, electrochemical and biological corrosion., It distinguishes between uniform, non-uniform, spot, selective, crevice, erosive, intercrystal corosion and corrosion cracking according to corrosion damage. It also presents corrosion testing options. In the experimental part, it describes the production of samples from gray cast iron, their dimensions, applied surface protection, hardness measurement and roughness measurement. This work also conducts electrochemical tests and tests in a condensation chamber on selected samples of gray cast iron GJL-250MnCuCr.
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Využití zinkových povlaků pro antikorozní ochranu ocelových součástí
Straka, Dominik
This Bachelor thesis „Use of zinc coats for anticorrosive protection of steel components“ characterizes corrosion and its effect on steel materials when being in a corrosive environment. Moreover, it categorizes corrosion and defines various methods of how steel materials can be protected against it. Special focus is given to protection using metal coats with lower electrode potential than Fe. Furthermore, this thesis determines particular methods of how to create metal coats depending on the type of material. Especially, the use of zinc applied by the hot-dipped and galvanic method is discussed. Quick laboratory tests are identified as a suitable method in order to evaluate the quality and resistance of created coats. Finally, lifespan and corrosive resistance of each coat are assessed considering the environment in which these coats are exposed.
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Methodology for the classification of corrosion aggressiveness of internal environments contaminated with volatile organic acids
Kouřil, M. ; Boháčková, T. ; Švadlena, J. ; Prošek, T. ; Strachotová, K. Ch. ; Kreislová, K. ; Fialová, P. ; Majtás, Dušan
The aim of the methodology is to specify the procedures for determining the corrosion aggressiveness of internal atmospheres for the area of historic preservation, especially in objects with an increased risk of volatile occurrence\norganic substances, which can endanger metal and other objects with their corrosive aggressiveness cultural and historical value. Target locations are, for example, archives, libraries, exhibition spaces and depositories of museums and churches and target objects of lead seals, organ pipes containing lead, stained glass windows, tin-lead dishes, technical monuments with lead solders, printing letters, etc.
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ELECTROCHEMICAL CHARACTERISTICS OF ADVANCED MAGNESIUM ALLOYS PROCESSED BY POWDER METALURGY
Minda, Jozef ; Nový, František (referee) ; Stoulil, Jan (referee) ; Hadzima,, Branislav (advisor)
The subject of the present dissertation is basic research in the field of advanced magnesium-based materials with high potential for medical applications prepared by powder metallurgy. These materials are evaluated in terms of corrosion behaviour in corrosive media by chemical composition and set conditions simulating the physiological environment of the human body (Hank's Balanced Salt Solution was used in this work). The aim is to analyze the influence of the processing parameters, chemical composition and structure on electrochemic characteristics of theprepared materials. For this purpose, a deeper of the the corrosion behavior, to obtain electrochemical characteristics and to investigate the degradation properties of the studied materials by means of electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), with elemental analysis by energy-dispersive spectroscopy (EDS) and other complementary methods. The materials for the experiments are prepared using powder metallurgy, which allows the formation of composites with compositions that do not match conventional manufacturing technologies. Thus, pure Mg samples were prepared at process parameters with pressing pressures of 100 and 500 MPa at 400 °C and also samples pressed at 500 MPa and room temperature were tested. Furthermore, MgZn composites prepared at a pressing pressure of 500 MPa and a temperature of 300 °C with a Zn content of 1, 5, 10 and 15 wt.% or MgZn composites pressed at a pressure of 500 MPa and a temperature of 400 °C with a Zn content of 1, 5 and 10 wt.%. Composites of the Mg-hydroxyapatite binary system pressed at 500 MPa and 400 °C with hydroxyapatite contents of 10, 20, 30 and 40 wt.% were also studied. The degradation mechanisms of these materials were investigated using the above mentioned methods and the basic electrochemical parameters and their evolution during the time of exposure were determined. From the results, the influence of process parameters, chemical composition and the corrosive environment itself on the studied materials is evaluated. Several materials that appear to be most suitable for the medical application are described and the causes of degradation behaviour at the level of the structure of the materials and their electrochemical interaction with the corrosive environment are also discussed in the dissertation thesis. Compaction and densification positively influenced pure Mg samples, where samples pressed at 500 MPa and 400 °C are further selected as reference material. Increasing Zn content positively electrochemically affects the corrosion resistance of MgZn series of samples pressed at 500 MPa and 300 °C, on the contrary, in the combination of electrochemical - microgalvanic and structural effects, low Zn content is optimal for MgZn composites pressed at 500 MPa and 400 °C. For Mg-hydroxyapatite materials, in agreement with the literature, it was shown that the most stable corrosion product layers with the best corrosion properties and evolution in time are formed for samples with hydroxyapatite content up to 10 wt.%.
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Metodika klasifikace korozní agresivity vnitřních prostředí znečištěných těkavými organickými kyselinami
Kouřil, Milan ; Boháčková, Tereza ; Švadlena, Jan ; Prošek, Tomáš ; Strachotová, Kristýna Charlotte ; Kreislová, Kateřina ; Fialová, Pavlína ; Majtás, Dušan
Corrosion of metal historical artefacts by volatile organic acids (VOA) is common in indoor atmospheres where VOA sources are present and where insufficient measures are taken to eliminate the aggressive effects of these substances on metals. The procedure for determining the corrosion aggressiveness of indoor atmospheres towards metals is defined in three parts of the standard EN ISO 11844 'Corrosion of metals and alloys - Classification of indoor atmospheres with low corrosion aggressivity'. The corrosion aggressivity classes (IC1 to IC5) are based, among others, on the determination of the mass loss of corrosion coupons of silver, copper, steel, zinc and lead. Lead was included in the first part of EN ISO 11844-1 in 2021, based on the results of the NAKI II project "Methodology for the classification of corrosion aggressiveness of indoor environments for lead alloy collectors" (DG18P02OVV050), as a metal specifically sensitive to the presence of volatile organic acids. The aim of the methodology is to specify the procedures for determining the corrosion aggressivity of indoor atmospheres for the field of conservation, especially in objects with a higher risk of the presence of volatile organic compounds, which can threaten metallic monuments by their corrosion aggressivity. Thus, target locations are, for example, archives, libraries, exhibition spaces and depositories of museums and churches, and target objects are lead seals, organ pipes containing lead, stained glass, pewter utensils, etc. The sources of VOCs include a range of materials that make up common furnishings in indoor environments - wood paneling and ceilings, furniture, cabinets, display cases, as well as other items on display or stored.
Fulltext:  PDF; PDF
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Measurement of corrosion resistance of the material
ŠVARCOVÁ, Denisa
Aim of the bachelor thesis is bringing the concept of corrosion closer to second grade pupils of elementary school. In the theoretical part of the work is summary of the concept of corrosion, types of corrosion and protection against corrosion. In the practical part is performed measurement of corrosion resistance of martensitic steel depending on temperature and time. The didactic part of the work consists of laboratory exercises, where the pupils try to measure the corrosion resistance of the material in different environments, and of worksheet, which is used to repetition and to complete of the concept corrosion.
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Assessment and the strengthening of the truss concrete roof structure
Rulíšek, Jakub ; Svoboda, Adam (referee) ; Klusáček, Ladislav (advisor)
My bachelor thesis is focused on the retrospective design and assessment of lattice prestressed trusses that serve as the roof structure of the hall building of the public transport depot in Brno in Medlánky. The aim of this thesis is to assess the structure according to currently valid standards, to determine the influence of potentially poor condition of the prestressing reinforcement on the stability of the structure and to design additional prestressing to ensure the safety of the truss.
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Effect of glucose on the corrosion behaviour of AZ31 magnesium alloy in saline solution
Faltýnková, Denisa ; Hasoňová, Michaela (referee) ; Doskočil, Leoš (advisor)
This bachelor thesis deals with the influence of glucose concentration on corrosion behaviour of magnesium alloy AZ31 in saline solution. The theoretical part briefly summarises the use of magnesium and its alloys in biomedical applications and offers insight into the current state of knowledge of the effect of glucose on corrosion of these materials. In the experimental part, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical behaviour of AZ31 alloy in saline solution with varying concentrations of glucose. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterise post-corrosion surface of the alloy. The corrosion environment was analysed by measurement of conductivity, pH, inductively coupled plasma atomic emission spectroscopy (ICP-OES) and liquid chromatography with conductivity detector. Results showed that glucose, depending on concentration, impairs corrosion resistance of AZ31 alloy in 0.9% NaCl. Three organic acids were identified in the corrosion environment, of which gluconic acid is the most abundant.
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Testing of high-temperature corrosion resistance of 16M03 steel
Šikl, František ; Kolomý, Štěpán (referee) ; Zemčík, Oskar (advisor)
The aim of this work is to design and perform an experiment that simulates the environment of a municipal waste incinerator. However, the whole process of corrosion in real life can take several years, so it is necessary to accelerate these processes in both higher areas and more aggressive environments. The investigated material is 16Mo3 steel. The first part of the work is a search of selected issues of corrosion and materials used in the energy industry. The next part of the work deals with the design of the experiment, which consists of several parts. These may include the appropriate choice of chemical compounds used or the choice of measured temperatures or sample preparation, the experiment being adapted to the available equipment of the BUT FSI workshop. In the last part of the work, testing of the specified material for temperatures of 900 °C, 975 °C and 1 050 °C is performed, while the composition of the mixture is designed as 35 wt. % Na2SO4, 30 wt. % KCl at 35 wt. % NaCl. The measured values are compared depending on the temperature, where, as predicted, a larger graphical dependence can be seen at higher values. At the end, the results of corrosion loss of 16Mo3 steel were compared with Inconel 625 superalloy, where the theory already differs from practice. Furthermore, chemical analyzes from the experiment were performed at 1 050 °C and, based on these obtained values, the proportion of individual elements can be adjusted with the salt mixture used. This adjustment is recommended to reduce the NaCl content due to the higher Na content, as well as to increase the KCl content due to the low K content.
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