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Laser surface cleaning
Macháček, Martin ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
This thesis covers feasibility of laser cleaning applied to various types of surface contaminations and treatments. In theoretical part of the theses are described basic principles of laser, a machine used in practical section (M200 by 4Jet) is introduced and corrosion and surface treatments are depicted. In practical part of the theses is described the preparation process of testing samples, the cleaning procedure and the results thereof are evaluated with emphasis on feasibility of the operation. The last section of the thesis focuses on comparison between conventional cleaning technologies and that of laser cleaning. Conclusion of the thesis summarises gained insights.
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Design of a mechanism for cleaning magnesium welding wire
Seidler, Filip ; Jaroš, Jan (referee) ; Slavíček, Jakub (advisor)
The bachelor's thesis dealt with the design of the mechanism for cleaning magnesium welding wire. In the first part of the work, a research was made for possible solutions and commercially available devices for cleaning wires. The applicability of the individual solutions was subsequently evaluated and, based on the evaluation, a custom solution meeting the specified conditions was proposed. The actual design used the principles resulting from the research of existing and unconventional solutions, which it further develops, thus managing to fulfill the requirements of the main and secondary objectives of the assignment. The design made it possible to remove impurities and corrosion from the surface of the magnesium welding wire meeting the specific conditions of the assignment.
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Corrosion of Aircraft Structures
Poláček, Juraj ; Juračka, Jaroslav (referee) ; Katrňák, Tomáš (advisor)
Presented bachelor's thesis deals with the corrosion attack of aircraft structures and their influence on the mechanical properties of individual parts of aircraft structures. The research part of the thesis describes the principles of corrosion attack formation and the influence of aggressive envi- ronments on their formation and development. The influence of aggressive environments is demonstrated through corrosion tests. The thesis maps the most commonly used materials in the aerospace industry. At the same time, it assigns specific materials to typical locations of aircraft structures. Through information and assistance with LOM Prague company, the thesis identifies and displays the most common corrosion-prone areas. Additionally, possible hazards arising from corrosion in specific locations of aircraft structures are described. The output of the thesis presents options for corrosion protection. This is especially the process of anodization, surface treatments, maintenance and appropriate material design in the development of aircraft structures. Due to the extensive use of the anodization process and surface treatments, an analysis was conducted to assess their impact on the mechanical properties of aluminium alloy 6061.
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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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Preparation and characterization of magnesium hydroxide on the surface of AZ31 magnesium alloy depending on the hydroxide cation used
Bejček, Martin ; Hasoňová, Michaela (referee) ; Doskočil, Leoš (advisor)
The bachelor thesis deals with the preparation and characterization of magnesium hydroxide on the surface of AZ31 alloy depending on the hydroxide cation used. The theoretical part focuses on magnesium and also on its alloys. Furthermore, corrosion in aqueous and chloride environments is discussed. The last chapter of the theoretical part focuses on the formation and preparation of magnesium hydroxide on magnesium alloys. The experimental part describes the actual hydrothermal synthesis of protective coatings on AZ31 magnesium alloy as well as the different methods used during the study. A temperature of 120 °C and different synthesis times (2h, 4h, 8h, 12h and 24h) were chosen as preparation conditions. The methods used included SEM-EDS analysis to document the surface and coating thickness of the material. This was followed by a potentiodynamic polarization method to determine the corrosion resistance of the prepared samples in a 0.15M NaCl. The last analysis was FTIR spectrometry, which served to determine the compounds that made up the protective coating. The results showed that the cations of the hydroxides used did not affect the morphology or the amount of prepared magnesium hydroxide on AZ31 alloy. The resulting coatings were characterized by good corrosion resistance compared to the reference AZ31 alloy. The best results were obtained for 24h samples. The thickness of the coatings reached 10 m at 120 °C and at a hydrothermal synthesis time of 24 h.
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Preparation and characterization of fluoride conversion coating on magnesium material
Šmíd, Jakub ; Doskočil, Leoš (referee) ; Březina, Matěj (advisor)
This thesis deals with the preparation of fluoride conversion coating on magnesium material. The effect of the coating time on the formation of the coating was investigated and the corrosion resistance of the resulting coatings was measured. The theoretical part is focused on magnesium and its alloys, powder metallurgy, corrosion and protection against it. Furthermore, conversion coatings, especially fluoride coatings, and their applications are discussed. The review section focuses on the current state of research in the field of fluoride conversion coatings. The experimental part describes the procedures of sample preparation and coating formation. The effect of time on the formation of the coating is investigated by monitoring the microstructure, mainly by elemental analysis of the surface of the samples in the section. Furthermore, the corrosion resistance of the samples is measured by potentiodynamic polarization in NaCl solution.
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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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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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