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Reactivity and controll of properties of metallic materials
Tkacz, Jakub ; Šoukal, František (referee) ; Zmrzlý, Martin (advisor)
This thesis is focused on corrosion protection of magnesium alloys AZ 91. Very important is material corrosion in some environments and last but not least surface treatment as grinding, polishing and etching. Theoretical part of this thesis is about magnesium and magnesium alloy. It focuses on properties, in order to determine the best procedure for corrosion protection. It characterize material corrosion- for example corrosion in special environment (atmosphere, water, etc.) or elektrolyte corrosion. Big part of theoretical part is focused on electrochemistry, in particular kinetic aspects (Tafel diagrams, corrosion current, etc.) and potentiostatic testing, where are observed properties of material in relation to potential: corrosion potential Ecorr, brakedown potential Ebd and repassivation potential Erp. This work present preparing, utilization and positive or negative aspects of corrosion protection. Metallography is important too since metallographical preparation is crucial for the research on the material. Described metallography procedures are mounting, grinding, polishing, etching and interpretation. Experimental part of this thesis is in particular about corrosion properties of magnesium alloy AZ 91. It focuses on calculation of corrosion rate in defferent environments. Principle is mass defekt of the alloy. The environments are: destilled water, hot service water and 3% NaCl solution (like sea water). Last but not least are important. procedure manipulation with materials. Very important are choice and composition of solutions, etching time, choice of polishing cloth, lubricant solution and good pressure. Beacuse of this aspects can be show corrosion action of environments on magnesium alloy AZ 91 by photographies.
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Passivation of magnesium alloys
Krejčířová, Dana ; Sponar, Jan (referee) ; Zmrzlý, Martin (advisor)
Diploma thesis deals with the technology of surface modifications of magnesium alloys. Basic knowledge from the field of the corrosion of metal materials. The division corrosion according to way of attack and corrosion environment, etc. There is an enumeration of ways of the corrosion defence. Questions of surface modifications with an emphasis on passivation by conversion coating and its analysis. Characteristics of magnesium and its alloys. Magnesium alloys with lithium, possibilities of its passivation and the verification of corrosion resistance. Enumeration of the used devices, chemicals and materials. characteristics of the used alloys. creation of the corrosion resistance standard. Research in passivation on the alloy containing 12 percent of lithium. The verification of the corrosion test usability based on the suggestion of the background research results. The test results for passivated as well as untreated samples and the reference material (steel). Aplication of chromate-free passivation and corrosion test on the alloy containing 12 percent of lithium.
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Protection of magneisum alloys
Ruttkayová, Veronika ; Wasserbauer, Jaromír (referee) ; Zmrzlý, Martin (advisor)
The aim of this bachelor thesis is to characterize the mechanical properties of protective coatings on magnesium alloy AZ91. In the introductory there are summarized the findings of magnesium, magnesium alloys, corrosion and protection against it. Important properties such as adhesion and hardness were tested by standardized tests. The result can be used to determine application fields of these coated alloys in practice.
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Corrosion protection of magnesium alloys
Minda, Jozef ; Ptáček, Petr (referee) ; Zmrzlý, Martin (advisor)
This work deals with an alternative procedure to conventional surface treatment of magnesium alloy AZ31 and AZ91 by fluoride coating layer. Synthesis of fluoride layers was carried out in the melt of NaBF4, while were following coating properties depending on the set process parameters, particularly temperature. The evaluation of coating were used scanning electron microscopy (SEM), light microscopy (LM) and immersion tests in 3.0% NaCl solution of 1, 8, 24, 48 h addition was carried out a short immersion test, in the strongly corrosive 70% HNO3. The coating was analyzed by energy dispersive spectroscopy (EDS or EDX) to determine the chemical composition. Tests showed very good corrosion resistance and showed that in this way, a reproducible compact coating was formed. The analysis identified a layer of stechiometric compounds MgF2 and NaMgF3. At the same time was the current research in the field of corrosion protection of Mg alloys. The prepared coating was confronted with current technology and in conjunction with searches were designed options such research can continue this kind of coating proceed.
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Magnesium alloys
Březina, Matěj ; Šoukal, František (referee) ; Zmrzlý, Martin (advisor)
The study is focused on corrosion and corrosion protection of magnesium and magnesium alloys. The theoretical part describes properties of magnesium and magnesium alloys. It shows their advantages as well as their disadvantages and discusses ideal use for these alloys. The theoretical part analyses basic corrosion characteristics and typical corrosion processes. It deals with types of corrosion protection and ways of its use. The experimental part was focused on metallographic analysis and corrosion behavior of magnesium alloy AZ91. Metallographic methods were used for preparing AZ91 to corrosion tests. The experimental part compared corrosion rate and degradation of pure AZ91 and AZ91 with conversion coating (phosphate-permanganate) in 3,5% sodium chloride solution in times: 1, 8 and 48 hours.
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The perspectives of hot bulk forming
Staněk, Vojtěch ; Císařová, Michaela (referee) ; Podaný, Kamil (advisor)
The project elaborated within bachelor study brings research work on the theme of perspectives of hot bulk forming. Forming technologies, their utilization so far, pertinence and supposed use in the future were reviewed on the basis of literary study. Further the importance of computer simulation and contemporary trends in processing of non-ferrous alloys are mentioned.
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Application of magnesium alloys castings
Pernica, Vítězslav ; Liškutín, Petr (referee) ; Roučka, Jaromír (advisor)
Magnesium alloys are still idle in technical applications because of their properties. The history of metal is not very old, the first application of its alloy started on the beginning of the 20th century. Magnesium is very light. Its weight is about one third less than the weight of aluminum and it is the third most frequented structural metal. However its preparation and processing can be problematical because magnesium has high affinity to oxygen. It causes intensive burning. During the century of stature have been improved both production and alloys. The usage of magnesium alloys took more importance and it is the most used alloy in automotive field sofar. Recently its demand expands mainly in electrotechnics. Next usage we can find in aeronautics, energetics, military and many other branches.
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Reactivity and controll of properties of metallic materials
Ševčíková, Barbora ; Opravil, Tomáš (referee) ; Zmrzlý, Martin (advisor)
The main objective of the bachelor thesis is to investigate the reactivity and corrosion of materials, namely of magnesium alloys. The theoretical part comprises a brief summary of the existing knowledge on magnesium alloys in the field of metal corrosion and a description of essential properties of the examined and utilized material. These are followed by the protection technology and a material resistance analysis including the specification of the processes applied in the experimental part. The thesis is focused on a comparison of the microstructure and corrosion resistance of magnesium alloys AZ31, AZ61 and AZ91. The applied methodology lied on metallography preparation of light optical micrographs of the surface-region cross-sections and on corrosion tests. These were carried out in 3% sodium chloride solution where the samples were immersed for the period of 8 hours.
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