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Titanium, Alloys and Intermetallics for Biological and Industrial Applications
Vespalec, Vítězslav ; Jech, David (referee) ; Čelko, Ladislav (advisor)
The creation of this Bachelor´s thesis was performed as a search retrieval, which includes basic information about titanium and its alloys. In the first chapter is stated history of titanium manufacturing. Following chapter include the most important property of pure titanium, such as alotropic modifications of the crystal grid, chemical, physical and technological characteristics, there is also space, that is assigned for using contemporary division of titanium alloys, detrimental effect of impurity, shape memory effect and intermetallics instance. Third part concern about selected application in industry. The conclusion pursue about biocompatibility factor and possibility use titanium and its alloys in implantology and dental applications.
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Structure and properties of weldment of rotor steels
Jech, David ; Jan,, Vít (referee) ; Foret, Rudolf (advisor)
The object of this thesis is to assess the structural stability of heterogeneous weld joint, which consists of two different base materials (16,537 steel and 16,236 steel) and weld metal NiCrMo2.5-IG with buttering layer P24-IG. All these materials belong to the group of low-alloyed creep-resistant steels that are to be used mainly in the power industry. The weld joint was made by application of the TIG hot wire welding method. Structural stability of this joint was evaluated by carbon redistribution and microstructural changes after annealing in temperature 300 °C and 400 °C during 500 hours. For modelling the phase composition of particular steels was used the ThermoCalc software. All gained results should be employed to appraise whether the heterogeneous weld joint of the steam turbine´s rotor is eligible for long-term operation in hard working conditions.
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Formation of Hypereutectic Aluminium Alloys Using Sacrificial Coatings
Gregor, Martin ; Jech, David (referee) ; Čelko, Ladislav (advisor)
Master‘s thesis deals with the forming of hypereutectic aluminium alloys using sacrificial coatings. Literature research is focused on analysing the characteristics of aluminium and its alloys. Attention is also focused to the heat treatment of aluminium alloys and the influence of alloying elements on these alloys. Analysis of characteristics and increase the useful properties of Al - Ni alloys is another object of literary research. Attention is also focused to the analysis of thermal spraying methods by focusing on the principle of individual methods and the characteristics of the coatings made by these methods. The object of experimental part is to prepare the hypereutectic aluminium alloys using sacrificial nickel based coatings. This is an unconventional manufacturing process comprising coating the surface of the aluminium substrate with using HVOF technology and subsequent thermal exposure. Furthermore, the work deals with the metallographic evaluation of prepared samples with a particular focus on the influence of temperature and time of heat treatment on the final structure of the experimental samples.
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Processing and Structural Stability of Nanocrystalline Thermal Barrier Coatings
Jech, David ; Ctibor, Pavel (referee) ; Ziegelheim, Jindřich (referee) ; Švejcar, Jiří (advisor)
Complex thermal barrier coating systems are one the most efficient high-temperature surface treatments which open up practical applications in land-based turbines and air jet engines. In the case of most exposed rotor and stator jet engine components, the combination of thermal barrier coatings together with the inner cooling system made it possible to increase working temperature by several tens of degrees of Celsius. Nevertheless, it is very difficult to achieve any further increase in working temperature by using the conventional thermal barrier coatings based on the ZrO2-Y2O3 ceramic top coat and the MCrAlY metallic bond coat, which currently work at their material limits. The working temperature inside the combustion chamber of the jet engine is proportional to engine’s efficiency and inversely proportional to fuel consumption and production of undesirable CO2 emission. Therefore, a considerable effort has recently been devoted to research and development of new types of ceramic coatings that can withstand long term extreme working conditions. New design approaches of multi-layer composite thermal barrier coating systems can sustain the required trend of increasing working temperature of jet engines mainly because of possibility of optimization of high-temperature durability and long lifetime. The theoretical part of thesis provides a fundamental overview of thermal barrier coatings, their properties, deposition technologies and testing methods. The experimental part is focused on optimization of deposition parameters of conventional ZrO2-Y2O3 / MCrAlY thermal barrier coatings prepared by means of atmospheric plasma spraying. Furthermore, a novel multi-layer thermal barrier coating system based on ZrO2-Y2O3-Al2O3-SiO2 / ZrO2-Y2O3 / MCrAlY, which contains amorphous and/or nanocrystalline regions, is developed, tested and characterized as well. Structural stability, phase transformations and growth of the thermally grown oxide in both conventional and experimental systems after high-temperature isothermal oxidation, cyclic oxidation and burner-rig tests were evaluated by means light microscopy, scanning electron microscopy with energy-dispersive microanalysis and X-ray diffraction. In comparison with the conventional thermal barrier coatings, the novel multi-layered systems have lower thermal conductivity, slower thermally grown oxide kinetic, better structural stability, and generally higher lifetime in all high-temperature tests.
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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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Development of materials used for downhill skis production
Václavík, Martin ; Jech, David (referee) ; Pavloušková, Zina (advisor)
The submitted thesis is a retrieval type and is concerned with the technologies and materials used in the manufacture of downhill skis with a deeper focus on the last ten years. Examined are materials for the manufacture of ski cores as well as other parts of the ski, and that in terms of comparison of the construction materials and technologies. Listed are basic elements and characteristics of skis, methods of manufacture, materials for the manufacture of individual parts of the skis and, last but not least, the types of skis. The work is eked out with the analysis of several samples of skis, on which were made cuts, they were observed and structures were compared. The aim of this observation was to determine whether the materials found in the practical section corresponds to the information contained in the theoretical part.
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The Application of Composite Materials in Automotive Industry
Beck, Branislav ; Jech, David (referee) ; Němec, Karel (advisor)
The aim of the bachelor’s thesis is to qualify the application suitability of the composite materials in the automotive industry. The first chapter offers the overview of selected composite materials, contains their basic classification and description of the basic components. The second part of this thesis is focused on the application of the composites in the automotive industry, discusses the advantages and disadvantages that are connected to the application of these technical materials.
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Processing and Structural Stability of Nanocrystalline Thermal Barrier Coatings
Jech, David ; Ctibor, Pavel (referee) ; Ziegelheim, Jindřich (referee) ; Švejcar, Jiří (advisor)
Complex thermal barrier coating systems are one the most efficient high-temperature surface treatments which open up practical applications in land-based turbines and air jet engines. In the case of most exposed rotor and stator jet engine components, the combination of thermal barrier coatings together with the inner cooling system made it possible to increase working temperature by several tens of degrees of Celsius. Nevertheless, it is very difficult to achieve any further increase in working temperature by using the conventional thermal barrier coatings based on the ZrO2-Y2O3 ceramic top coat and the MCrAlY metallic bond coat, which currently work at their material limits. The working temperature inside the combustion chamber of the jet engine is proportional to engine’s efficiency and inversely proportional to fuel consumption and production of undesirable CO2 emission. Therefore, a considerable effort has recently been devoted to research and development of new types of ceramic coatings that can withstand long term extreme working conditions. New design approaches of multi-layer composite thermal barrier coating systems can sustain the required trend of increasing working temperature of jet engines mainly because of possibility of optimization of high-temperature durability and long lifetime. The theoretical part of thesis provides a fundamental overview of thermal barrier coatings, their properties, deposition technologies and testing methods. The experimental part is focused on optimization of deposition parameters of conventional ZrO2-Y2O3 / MCrAlY thermal barrier coatings prepared by means of atmospheric plasma spraying. Furthermore, a novel multi-layer thermal barrier coating system based on ZrO2-Y2O3-Al2O3-SiO2 / ZrO2-Y2O3 / MCrAlY, which contains amorphous and/or nanocrystalline regions, is developed, tested and characterized as well. Structural stability, phase transformations and growth of the thermally grown oxide in both conventional and experimental systems after high-temperature isothermal oxidation, cyclic oxidation and burner-rig tests were evaluated by means light microscopy, scanning electron microscopy with energy-dispersive microanalysis and X-ray diffraction. In comparison with the conventional thermal barrier coatings, the novel multi-layered systems have lower thermal conductivity, slower thermally grown oxide kinetic, better structural stability, and generally higher lifetime in all high-temperature tests.
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