|
|
Metallography of stainless steels
Hasoňová, Michaela ; Kalina, Lukáš (referee) ; Zmrzlý, Martin (advisor)
This thesis deals with metallography of stainless steels. At the beginning of theoretical part the history of metallography is shortly summarized. Then the basic knowledge about metallography, ways and methods of preparing samples for subsequent analysis of structure are resumed. There are also summarized methods for examining the macrostructure and microstructure of materials with a particular focus on stainless steels. The literary-search section summarizes recent advances in the study of the structure of materials using methods of metallography. The task of the study was to find suitable composition of etchant to reveal the structure of stainless steels in order to achieve high quality and especially reproducible results.
|
|
|
Analyse and Optimise Production Process of Prototypes
Hamr, Tomáš ; Zatloukal, Miroslav (referee) ; Starý, Jiří (advisor)
This diploma thesis summarizes basic findings about issues of making development samples of PCB. The emphasis is especially on required quality which complies with mentioned norms. The theoretical section includes methodology for evaluating quality dismounted boards, assembling and soldering, parameters of components under different environmental circumstances. The practical part is carried out in cooperation with the department EEG in R&D Automotive Lighting Jihlava. It is dedicated to the design and the preparation of development samples where the quality is assessed according to given methodology from the theoretical part. PCB are analyzed by an X-ray, metallographic grinding and other methods. Recommendations are given and based on results for improvements.
|
|
|
Welding technology of turbine rotors
Pivoňka, Vít ; Kubíček, Jaroslav (referee) ; Daněk, Ladislav (advisor)
The paper deals with all the possibilities which can be used to weld the rotors of turbines, both the root and the filler welding. All these methods are thoroughly analyzed and their properties are described, especially the size of the heat input by welding of rotors of turbines. Further in this work is described the organization of the structure by means of a metallographic survey and a test of welds and materials, which are performed to check whether the material and the welding method are suitable for welding of rotors of turbines. In the experimental part are described all welds made by different welding parameters, one of these welds is chosen to achieve the best welding of the weld root. This weld is further investigated for hardness and change of microstructure after welding.
|
|
|
Haigh diagram of selected spring steel
Zejdová, Lucie ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
This master’s thesis focuses on the fatigue properties of spring steel 54SiCrV6. The theoretical part deals with the properties and use of spring steel and metal response to cyclic loading. The main aim of this work was to obtain the basic mechanical properties as well as the hight cycle fatigue data. Additional metallographical evaluation of microstructure.
|
|
|
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.
|
|
|
Advanced metallographic techniques for aluminum and its alloys
Rychlý, David ; Gejdoš, Pavel (referee) ; Mikmeková, Šárka (advisor)
Hlavním cílem této práce je optimalizovat metalografickou přípravu hliníku pro specifické potřeby rastrovací elektronové mikroskopie. Rastrovací elektronová mikroskopie je velice citlivá na kvalitu připraveného povrchu a základní metody přípravy užívané pro světelnou mikroskopii jsou nedostatečné. Práce se zaměřuje na optimalizaci a hledání nových metalografických metod, které splňují vysoké požadavky rastrovací elektronové mikroskopie. Povrch musí být připraven co nejkvalitněji, bez defektů a artefaktů z přípravy. Jako testovací materiál pro experimenty byl vybrán čistý hliník. Základní a pokročilé metody přípravy byly experimentálně testovány a nejvíce slibné postupy poté optimalizovány. Několik různých variant přípravy povrchu bylo vyzkoušeno v rámci metod koloidních silik a elektrolytického leštění. Připravený povrch byl následně zkoumán pomocí světelné mikroskopie, rastrovací elektronové mikroskopie s nízkými urychlovacími napětími a konfokální mikroskopie. Závěrem byl stanoven optimální metalografický postup vyhovující vysokým požadavkům elektronové mikroskopie a zajišťující připravený povrch s minimem defektů.
|
|
| |
|
|
Production process optimization
Hejzlar, Aleš ; Vacek, Jan (referee) ; Fiala, Alois (advisor)
This diploma thesis deals with the production process optimization. The cutting operation and the lathe-turning issue is described in this thesis. In the practical part the production process is analyzed, the designed experiment (DOE) is suggested and evaluated. In the end of the practical part there is the evaluation of the machined material in the light of microstructure. On the basis of the partial findings the enclosures are done and the recommendations leading to the production optimization are suggested.
|
|
|
Color metallography of foundry alloys
Nekuda, Pavel ; Záděra, Antonín (referee) ; Kaňa, Václav (advisor)
The theoretical part of the diploma thesis deals with the preparation and application of the most common color etchants and in the practical part, the applicability of selected reagents is tested. The obtained results are compared with the findings obtained from previous research works. Attention was mainly focused on etching samples of alloyed cast irons with Beraha's I, Beraha-Martensite and Beraha's CdS reagents in order to find the optimal method of color etching of austempered ductile iron. These samples differed in their chemical composition and wall thickness of the initial Y-block. Image analysis was also performed, where the sizes of the individual color areas, obtained by the Beraha's I reagent, were determined on the microstructures. The practical part of the thesis also deals with the application of Weck's reagent on two samples of AlSi7Mg silumin, while only one of them was heat treated.
|
|
|
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.
|
guest ::
