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Surface and mechanical properties of a-CSi:H and a-CSiO:H films
Plichta, Tomáš ; Shukurov, Andrey (referee) ; Klapetek, Petr (referee) ; Čech, Vladimír (advisor)
The dissertation thesis deals with the preparation and characterisation of a-CSi:H and a CSiO:H thin films prepared using the process of plasma enhanced chemical vapour deposition (PECVD). Tetravinylsilane (TVS) and its mixtures with argon and oxygen were used to deposit films on both planar substrates and fibre bundles. Main characterisation techniques were employed to study the topography of films, namely atomic force microscopy (AFM). Their mechanical properties were studied through nanoindentation; the nanoscratch test was used to assess the film adhesion to the substrate. Other analysed properties were internal stress and friction coefficient. The particular attention was paid to the work of adhesion and its determination. This knowledge was further applied to the preparation of surface treatments of glass fibres and, subsequently, polymer composites. Those were tested using the push-out test and the short beam shear test. Based on the results, the effects of deposition conditions and the relationships between the studied properties and quantities were determined.
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Mechanical properties Al-alloy EN AW 7020 at increase temperatures
Slouka, Marek ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
The master’s thesis deals with high strength aluminium alloys AlZn4Mg (EN AW 7020). This alloy is used for high strength, low density, a good corrosion resistant and a good weldability in protective atmospheres. At first this thesis is described to aluminium alloys, ways of manufacturing and history. Next this thesis mainly deals with wrought aluminium alloys, heat treatment this alloys and alloys Al-Zn-Mg. Tensile tests were made of alloys EN AW 7020 at room temperature and increased temperature. Next this alloy was made of fatigue test and metallographic analysis. The model was construct. This model describe to behaviour alloy at increased temperature and this model was compared with measure values. This thesis describe to behaviour of study alloy at room temperature and increased temperature.
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Founding in region of Velké Bílovice
Moravčík, Martin ; Masopust, Jan (referee) ; Brdečková, Helena (advisor)
Bachelor's thesis got two parts. In teoretical part I examene geology and geomorfology of region Velké Bílovice. Half of practical part analyse laboratory samples that are taken from Velké Bílovice. I tested samples for physical and index properties and mechanical properties. Second half of practical part is design and assessment of gravity wall by EC 1997. Earth pressures are calculated by ČSN 73 0037. Geological conditions for gravity wall are calcareous clays from examined properties and loess by [5]. Assessment was controled with computer program GEO5.
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Mechanical properties of magnesium alloy AZ91E prepared by ECAP method
Darida, Jiří ; Válka, Libor (referee) ; Pantělejev, Libor (advisor)
This thesis deals with mechanical and fatigue properties of magnesium alloy AZ91 processed by EX-ECAP method. This method involves the application of extrusion followed by equal-channel angular pressing. To obtain basic mechanical characteristics, the tensile test were carried out at room and elevated temperatures. Further the fatigue tests were performed and obtained data were used to compile S-N curve. The work also includes metallographics analysis of microstructure and fractographic analysis of fracture surfaces of tensile and fatigue test specimens.
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Using simulation to predict defects in and evaluate properties of die-cast Al-alloy castings
Morávková, Jitka ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
The purpose of this diploma thesis is comparing the quantity of porosity in die-cast aluminium casting with using simulation. The cast engine blocks were made by high pressure die-casting and a local squeeze casting (LSC) technology. There was also examined the relationship between porosity and mechanical properties of castings. There were evaluated and compared the results of my own measurements with data from previous students theses at the Faculty of Mechanical Engineering BUT. All data were tested by statistical tests. The comparison of simulation results and experimentally measured values was found a good programme-ability to simulate and estimate porosity.
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Application of fly ashes from fluid bed coal combustion within refractory materials
Kotrla, Jan ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the possibility of utilization of fluid ash in refractory materials and its influence on resulting properties. This work studies the effect of bed and filter ash addition on properties of the droplet and resulting mechanical properties, bulk density, shrinkage and firing temperature of stove fireclay. The subject of this thesis is also reduction of SO2 emissions evolved burning of fireclay containing fluid ash rich of anhydrite. Emissions of SO2 were observed by TG-TDA-EGA method. Characterization of prepared samples and study of heat treatment processes was based on XRD, TG-DTA-EGA, TDA, SEM–EDS, heating microscope and isothermal calorimetry.
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New Aluminium Alloys in Aircraft Structures
Przeczek, Jan ; Šplíchal, Jan (referee) ; Klement, Josef (advisor)
This bachelor work deals with newly developed wrought aluminium alloys, designed for application in aerospace industry. The task of that work is to compare recent aircraft aluminium alloys with conventional alloys and indicate direction of progress in this field. The comparison is particularly focused on improvement of mechanical and/or technological properties of these alloys.
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Evaluation of porosity in gravity - cast Al - alloy castings
Staňková, Markéta ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
Solving of this diploma thesis is evaluation porosity in sequence on mechanical properties from different Al alloys. Castings were made by gravity casting to the iron-mould or gravity casting to the sand. Measurements (mechanical properties, porosity, DAS - dendrite arm spacing, shape factors and sphericity) were statistically analysed and dependencies which were detected were processed to the graphs.
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Heat treatment of formed parts
Poloch, Milan ; Peterková, Eva (referee) ; Lidmila, Zdeněk (advisor)
Bachelor thesis focusing on heat treatment of formed parts. The chapter of basic termsdeals with steels for forming. Concrete formability and influence on plastic deformationson steel properties, influence of chemical composition, structural composition and termomechanical conditions during deformation. In the larger parts of the thesis are carriedout heat treatment. The prohibited concepts of heat treatment are explained in the in-troductory question and some follow the basic methods and then the basic methods ofheat treatment such as annealing and tempering with tempering are explained. All ofthese technologies have their own subchapters and are illustrated and supplemented withgraphs and figures. The practical amount consists of plastic deformations of roller-shaped samples. The samples were deformed, measured hardness, heat treatment followed bymeasured hardness. Changes of mechanical properties on samples are evaluated.
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The Influence of the Isothermal Transformation Dwell on the Structure and Mechanical Properties of ADI
Falta, Petr ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
The thesis ,,The Influence of Transformation dwell on the Structure and Mechanical Properties of ADI´´ deals with problems of optimal properties of the unalloyed nodular cast iron, which are obtained by the heat treatment. The heat treatment consists of austenitization and then rapidly quenching to the transformation temperature, isothermal transformation and water cooling in the end. The aim of the thesis is focused on estimating the influence of isothermal transformation on the content of stabilized austenite, static mechanical properties and on the fatigue properties in high-cycle fatigue region for selected samples. The theoretical part of this work analyses the production of the nodular cast iron and its possibilities of the heat treatment, final technological and mechanical properties. Furthermore, it examines the conditions of austempering (temperature and time of isothermal dwell), which has a fundamental influence on mechanical properties of ADI. Problems of fatigue properties are described at the end of this part. The experimental part contains a chemical composition of studied samples and their metallographic analysis. Among others the basic mechanical static properties were determined as well as the Wöhler curves including values of fatigue limits for ten on seventh cycles. Wöhler curves were obtained by a mathematical processing using data reached by fatigue tests.
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