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Relationship between tensile strength and hardness of aluminium alloys
Růžička, Martin ; Jetela, Václav (referee) ; Klement, Josef (advisor)
This thesis deals with relationship between tensile strength and hardness of aluminium alloys. The introduction provides an overview of aluminum aloys and their properties. In the following section there is an analysis of the processing of aluminum alloys. A large part is devoted to the course of precipitation hardening. The second part of the thesis contains a practical part, which describes the methodology of measuring hardness and tensile strength. The measurement process is described below. At the end, the measured data are processed into various graphs and their results are evaluated.
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Influence of the electron beam trajectory on the surface properties of steel 42CrMo4
Mikuš, Tomáš ; Kouřil, Miloslav (referee) ; Foret, Rudolf (advisor)
The thesis deals with surface quenching of steel 42CrMo4 by electron beam. Influence of technologic parameters and beam deflection on properties and structure of prepared layers is studied. Electron beam surface quenching was applicated with and without melting of the surface. Structures of layers made by electron beam quenching were compared with structures made by laser and electromagnetic induction. Structures and phases were analysed by optical microscopy, SEM and roentgen diffraction. Hardness was measured on hardened layers.
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Advanced Abrasion Resistant Coatings for Vacuum Systems
Hégr, Eduard ; Kudláček,, Petr (referee) ; Hrubý, Vojtěch (referee) ; Švejcar, Jiří (advisor)
The thesis is focused on research of advanced surface resistant coatings which have a direct effect on increasing of functional properties of vacuum systems (eg reducing wear of individual pump components, surface inertia to aggressive gases/molecules). But they can also secondarily affect other important pump properties (eg reducing pump temperature). The studied layers/coatings are divided into three areas (i) hard anodic layer, (ii) hard anodic layer with PTFE coating and (iii) DLC coating. The initial material (substrate) is an aluminum-based alloy, which was used for this purpose. In presented thesis, the influence on increase of material and physical properties was demonstrated, such as the increase of hardness and abrasion resistance of the surface after the application of the anodic layer with PTFE coating. The theoretical part of thesis describes the basic principles of preparation of abrasion-resistant layers/coatings and also introduces the vacuum physics. It shows the basic principles of obtaining vacuum, which give a comprehensive picture of the importance of working with advanced coatings. The experimental part is divided into the evaluation of the microstructure of the sample material and the second part is focused on the experiments needed to obtain/measure the required properties, which can be further used to predict damage of the layers/coatings.
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Influence of thermal processing to microstructure of various steels
Kocman, Lukáš ; Havlík, Petr (referee) ; Štěpánek, Roman (advisor)
This bachelor thesis deals with the heat treatment of steel, especially measuring the influence of individual heat treatment technologies on changes in the microstructure of steels. The theoretical part of the work presents alloys of iron and carbon, furthermore describes their phase transformations in the solid state, particularly the transformation diagrams of steels. In another part of theoretical part, the basic heat treatment technologies and their influence on the mechanical properties and microstructure of steels are described. The experimental part deals with the preparation of metallographic samples and presents results of examining the microstructure and measuring the hardness of individual samples. At the end of the work the synthesis of the theoretical part and results of the experimental part is used for the partial and overall evaluation of the influence of heat treatment on the microstructure of steels.
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Effect of heat treatments on the microstructure and hardness of high-entropy alloy
Jesenská, Mária Ľudmila ; Adam, Ondřej (referee) ; Moravčíková de Almeida Gouvea, Larissa (advisor)
V tejto práci je študovaná neekviatomická Al0.2Co1.5CrFeNi1.5Ti vysoko entropická zliatina, ktorá bola vyrobená pomocou vákuového indukčného tavenia. Zliatina v odliatom stave bola analyzovaná a tepelne spracovaná pri teplote 1000 °C po dobu 5h, a následne podrobená tepelnému spracovaniu pri teplote 750 °C po dobu ďalších 5h, s cieľom skúmania vplyvu teploty a doby tepelného spracovania na fázové zloženie, mikroštruktúru a mechanické vlastnosti. Na vyhodnotenie možných fáz prítomných v zliatine bol použitý pseudobinárny fázový diagram (CALPHAD). Mikroštruktúra zliatin bola charakterizovaná a chemicky analyzovaná pomocou röntgenovej difrakcie (XRD), elektrónovej mikroskopie (SEM) a energeticky disperznej spektroskopie. Výsledné vyhodnotenie tvrdosti materiálu prebehlo pomocou skúšok mikrotvrdosti a nanoindentácie.
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Preparation and Characterization of Porous Magnesium Based Materials
Březina, Matěj ; Pacal, Bohumil (referee) ; Vojtěch, Dalibor (referee) ; Ptáček, Petr (advisor)
Bulk magnesium materials produced nowadays via powder metallurgy are based on a vastly extensive technological spectrum, which makes it possible to create a wide range of materials. This work focuses on the preparation of bulk materials from magnesium powder by cold pressing and hot pressing, sintering and field assisted sintering. The bulk materials were prepared in a series of compacting pressures from 100 MPa to 500 MPa and the sintering temperatures were selected in the range of 300 ° C to 600 ° C in order to characterize the influence of the manufacturing conditions and technology on the final properties of bulk materials. Prepared materials were evaluated in terms of microstructure, hardness, microhardness, three-point bend test, and fractography. From the hot pressed materials, the samples prepared at 400 and 500 MPa and 400 °C had the highest strength and hardness. The classic sintering of magnesium in the furnace with argon atmosphere proved to be ineffective due to the oxide layer on the surface and the presence of oxygen in technical argon. The SPS sintering (Spark Plasma Sintering) was the more effective with the lower applying pressure used to make the preforms and with the higher applied pressure during the SPS process itself. Highest strength and hardness were achieved in this case of materials sintered at 600 ° C prepared from free powder and the most porous preform (100 MPa). The bulk materials were prepared using all methods used, but the properties of these materials varied considerably depending on the technology used.
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Surface hardening of steels by high power diode laser
Bazalová, Lucie ; Daněk, Ladislav (referee) ; Mrňa, Libor (advisor)
The master thesis deals with the technology of surface hardening of steels by high power diode laser. The thesis is an experiment of surface hardening of steel 12 050 on various parameters of speed movement of the laser head and used power. At first, the work deals with the possible technology of surface hardening, industrial lasers and possible methods for measuring hardness. It describes the material used and the evaluation of the macrostructure and microstructure of the samples and evaluates the achievement of hardness, depending on the distance from the surface. The results are used to assess the suitability of the parameters during quenching.
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Special unit to test hardness.
Kolář, Ladislav ; Prokop, Jaroslav (referee) ; Kalivoda, Milan (advisor)
The goal of this work is to provide simple overview in the field of devices for measuring hardness with a focus on new technologies used by modern devices. This work should indicate the suitability of the use of different measurement methods for specific conditions and get acquainted with some measuring device on the current market.
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