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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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Microstructural classification of multiphase steels by advanced microscopy and image analysis techniques
Jozefovič, Patrik ; Materna, Jiří (referee) ; Mikmeková, Šárka (advisor)
Austenitické nerezové ocele si vďaka svojim charakteristickým vlastnostiam našli uplatnenie naprieč rôznymi sektormi. Metastabilný charakter niektorých z nich, ktorý umožňuje martenzitickú tranformáciu so sebou však prináša určité riziká spojené s poklesom húževnatosti. Na odhalenie martenzitickej fázy v mikroštruktúre oceli sa v dnešnej dobe využívajú techniky ako je napríklad difrakcia spätne odrazených elektrónov v rastrovacom elektrónovom mikroskope. Difrakcia spätne odrazených elektrónov je však veľmi časovo náročná a takisto kladie vysoké nároky na kvalitu metalografickej prípravy vzoriek. Cieľom tejto práce je nájdenie iných techník, umožňujúcich separáciu fáz v metastabilnej austenitickej oceli v rastrovom elektrónovom mikroskope, ako aj optimalizácia metalografickej prípravy tejto oceli pre potreby elektrónovej mikroskopie. Po naplnení týchto cieľov sa táto práca zameriava na možnosť využitia takzvaného hlbokého učenia za účelom automatizovanej separácie fáz v mikrosnímkach z rastrovacieho elektrónového mikroskopu. Pre tieto účely boli natrénované 4 neurónové siete založené na rôznych architektúrach a ich výsledky boli následne porovnané.
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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 material base of trial bicycles
Debs, Martin ; Hanusová, Petra (referee) ; Jan, Vít (advisor)
This bachelor thesis is focused on the material analysis of trial bicycle parts. The main aim is the summary of materials and technologies used in construction of these bicycles, exploiting knowledge of material microstructure theory, both in theoretical and practical sections of the thesis. To attain the aims, it was necessary to perform a proper metallographic specimen preparation. These specimens allowed to observe a material microstructure of various bicycle parts and demonstrate the use of metallographic techniques for determining the type of the used materials and applied processing technologies. Comprehensive metallographic analysis proved the use of materials in ordinary quality and ordinary technological processes. Subsequently we documented and explicated various defects in microstructure of the examined parts.
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Costs reduction in production of Al-alloy castings
Nováková, Lucie ; Lána, Ivo (referee) ; Roučka, Jaromír (advisor)
This thesis deals with solving the most serious internal defects in castings made of aluminum alloys which are cast in sand molds in Slévárna a modelárna Nové Ransko Ltd. The problem solving contains a description of the problematic castings with the investigation of the structure and phases and subsequent detailed analysis of their production. The Author of this thesis also examines the influence of Fe and Mn on a possible formation of the internal porosity with the help of test meltings with the evaluation of the internal structural change. The Author’s design solution is a close checking of chemical composition with regard to the ratio Mn / Fe present in the alloy, the purchase of Foundry Degassing Unit to reduce gassiness of melted metals and better control of gassiness with the help of the appropriate equipment for the density Dichte index.
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Influence of solidification conditions on structure and properties of austenitic chrome-nickel steels
Ambrož, Ondřej ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
The thesis deals with the influence of solidification conditions on structure and mechanical properties of austenitic stainless steels. The first part involves the distribution of stainless steels and a basic understanding of the issue of achieving the desired structure and mechanical properties. The second part is focused on austenitic steels and their basic characteristics. This section also describes the experiment and the results achieved. Finally, these results were evaluated and further research steps were recommended.
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Heat and mechanical resistance of zinc coating
Horák, Karel ; Dzimko, Marián (referee) ; Černý, Michal (advisor)
The work is aimed at studying the thermal degradation of the protective zinc coating. Its large part deals with the structure of the various stages of transition and their arrangement, the main emphasis is on analysis of brittle intermetallic phases, which arise due to increased temperature. Conclusion of the work is trying to clear itself causes degradation of this protective layer.
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Evaluation of the use of non-destructive methods of acoustic emission on materials
Vašíková, Simona ; Zimáková, Jana (referee) ; Binar, Tomáš (advisor)
This master thesis is about acoustic emission itself and acoustic emission as a nondestructive method of testing materials. There are different types of metal materials corrosion too. In this thesis is possible also find corrosion protective methods. There are practical examples of use the acoustic emission method at metal materials corrosion from automotive, aviation, food processing and manufacturing industry with construction and civil engineering examples. The experimental part is focused on samples preparing and measuring the acoustic emission signals during continual corrosion process of grey cast iron in condensational corrosion chamber. These results are supported and completed with metallographic analysis.
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