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Mechanical properties of Nodular Cast Iron prepared by method Tundish and process Initek
Vítek, Radovan ; Hotový, Ivan (referee) ; Věchet, Stanislav (advisor)
This bachelor thesis deals with a properties and production of nodular cast iron. The first section describes the classification, distribution and structure of nodular cast iron. The second part is focuses on the description of nodular cast iron, modification, inoculation and production. A strong effort is made on the production of nodular cast iron using the Tundish Cover method and the Initek process. In conclusion, the structure of the material is evaluated on samples that were delivered for metallographic analysis. The final evaluation of the structure of the material is used to compare the mechanical properties of a nodular cast iron produced by Tundish Cover method and Initek process.
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Grain growth kinetics study of advanced oxide ceramic materials
Kazda, Adam ; Kachlík, Martin (referee) ; Pouchlý, Václav (advisor)
The goal of this work was to study the grain growth kinetics of five different materials: tetragonal ZrO2 (doped 3mol.% Y2O3 and particle size 80 nm), two cubic ZrO2 (doped 8 mol.% Y2O3 and particle sizes 80 and 140 nm) and two hexagonal Al2O3 (with particle sizes 100 and 240 nm). These ceramic powders were isostatically pressed and then they were isothermally sintered at 3 different temperatures for 1-60 hours. The biggest coarsening was discovered during temperature increase to sintering temperature. The dwelt at sintering temperature was not so important for coarsening. The activation energy of grain growth QG, growth exponent n and kinetic constant k0 were discovered for four materials. The activation energy of grain growth was 511±49 kJ/mol for tetragonal ZrO2, 645±84 kJ/mol for cubic ZrO2 a 428±75 kJ/mol a 606±24 kJ/mol for Al2O3. Possibility of kinetic window of sintering process for cubic ZrO2, tetragonal ZrO2, and Al2O3 with particle size 240 nm (doped MgO) were discovered by comparison of established activation energy of grain growth QG with activation energy of sintering QS from literature. Kinetic window of sintering process wasn’t found for high purity alumina with particle size 100 nm.
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Study of AlSi protective coating after degradation
Vítková, Gabriela ; Řičánková, Veronika (referee) ; Hutařová, Simona (advisor)
Materials used for high temperature applications works in a very aggressive environment (oxidation, hot corrosion, erosion, fatigue, creep). Demands on these materials are very high. Nickel-based superalloys show the certain stability in this environment. Improved resistance to oxidation and hot corrosion can be achieved by using protective layers such as diffusion barriers. This thesis is focused on changes of microstructure and properties of AlSi layer applied by „slurry“ method on nickel-based superalloy Inconel 713 LC, due to long-term thermal exposition at 800, 900 a 1000 °C.
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Cutting ceramics
Vaverka, Ivo ; Sámelová, Vendula (referee) ; Humár, Anton (advisor)
The Bachelor Thesis is focused on cutting ceramics which belongs to tool materials. The first part deals with sorting, application and characterization of basic materials for cutting tools. The cutting ceramics itself is thoroughly analysed from a historical perspective, default materials, production, physical and mechanical qualities and microstructure in the second part. The last part contains the assortment of CeramTec, Greenleaf and Saint-Gobain.
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Structure and properties of welded joints of steam turbine rotor
Machala, Jan ; Hutařová, Simona (referee) ; Juliš, Martin (advisor)
This thesis deals with the assessment of the structural-mechanical properties of welded joints of steam turbine rotor. Experimental weld material is low alloy steel 30CrMoNiV5-11 in the state after the artificial degradation. The theoretical part of the literary researches the issue, focusing on the weldability of different types of steel used in the energy industry, the metallurgical processes in welding and provides an overview of the most important methods of welding. Great attention is paid to the evaluation of weld quality in accordance with relevant standards and destructive and non-destructive testing of welded joints. In the experimental part of this work was carried out measurements of hardness and microhardness of the weldment by Vickers and evaluation of the microstructure by light microscopy. The obtained values and information about the properties of the material after artificial degradation were compared with previously obtained experimental results in the default state (after annealing).
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Analysis of friction welding by SFW process
Šajkovics, Patrik ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
Bachelor thesis developed in the bachelor study focuses on the analysis of friction welding by SFW process. The work is focused on a detailed description of the principle of technology SFW and its other modification. It describes the microstructure of the welds and it depends on the mechanical properties. Were summarized advantages and disadvantages, industries which the SFW used, suitable materials for welding and material of welding tools. SFW technology is focused on non-ferrous metals and their alloys, but the conclusion is also mentioned steel welding technology SFW and material of tools are suitable.
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Weldability of steels for steam turbine parts
Jech, David ; Hutařová, Simona (referee) ; Juliš, Martin (advisor)
The aim of contemporary standard welding technologies is to create compact welds with high value of solidity and toughness in laboratorial and operational conditions. This welding technology is asserted in new creep - resisting steels on basis of steel CrMoV and CrMoNiV, which have high value of solidity and creep - resistance. The thesis deals with problems connected with the weldability of steels for steam turbine rotors and it´s aim is to interpret the structural and mechanical features of the weld joint for material combinations under consideration. For the assessment of weld joint features has been used measuring of micro hardness and hardness according to Vickers, microstructure was observed by methods of light microscopy.
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Preparation of bioceramic materials for medical applications
Doboš, Petr ; Šoukal, František (referee) ; Palou, Martin (advisor)
The aim of this work was to prepare hydroxyapatite powder by sol-gel and precipitation method. Then, the powders were pressed and sintered at 500 °C, 800 °C and 1100 °C. These samples of HAP were analyzed by FTIR, XRD, SEM methods. The microstructure measurement by SEM indicates that the size HAP particles varies from micro to nano meter. The average size of dominant particles is determined around 5 – 8 µm with surrounding fine particles of 1 µm size. The in vitro bioactivity of HAP samples was investigated by immersing them in Simulated Blood Fluid for 4 weeks. The work reports the result of mikrostructure analysis of samples after immersion. The bioactivity was influenced by the sintering temperature. It is evident, that the layer of the new hydroxyapatite phase formed during immersion on the surface of initial HAP samples changes with temperatures.
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Microstructure and Mechanical Properties of Steels
Stavinoha, Jakub ; Pavloušková, Zina (referee) ; Molliková, Eva (advisor)
This bachelor’s thesis is concerned with studies of relationships between grain size and mechanical properties of steels. Theoretical part deals with structure of the steels, with reaction of the material to the external stress, methods of estimating the grains size and strain-stress diagrams. In the practical part there are evaluated scratch patterns and strain-stress diagrams of steel C10E4Cu3+N. The conclusion of thesis includes the evaluations of the results from practical part and comparison with the theoretical part.
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The Structure and Properties of Cast Ceramic EUCOR
Klimentová, Jiřina ; Trunec, Martin (referee) ; Pavloušková, Zina (advisor)
The diploma thesis deals with cast ceramics EUCOR which can be described as three-phase system, composed of corundum, baddelyite and a glassy phase. The study was focused on the analysis of structure and phase composition of the material, together with the assessment of their influence on the basic mechanical characteristics. The techniques of light and scanning electron microscopy were used together with energy-dispersive microanalysis, X-ray diffraction and microhardness measurement.
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