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HEAT – MECHANICAL DEGRADATION OF SURFACES AT THE HIGH TEMPERATURES
Zahradník, Radek ; Hajduk, Daniel (referee) ; Čecho, Ladislav (referee) ; Toman,, Zdeněk (referee) ; Raudenský, Miroslav (advisor)
The Ph.D. thesis is focused on a surface degradation mechanisms under combined heat and mechanical load. The objects of examination are work rolls from hot rolling mill which suffer such a load. In first chapter, the hot rolling process, the design, the manufacturing process and present materials of work rolls are described. The state-of-the-art study of work roll surface degradation mechanisms – wear, oxidation, thermal and contact fatigue are described in the second chapter. The characterization, the formation, the mechanisms of progression and the effects of each surface degradation mechanism is described step by step. The state-of-the-art study of analytical and numerical models which are related to hot rolling process is described in third chapter together with their limitations and flaws. The next chapters contain design of an analytical, an optimized macroscopic and a microscopic model for study of the work roll stress state. The macroscopic and the microscopic model is based on finite element method and they are implemented in ANSYS Programming Design Language. The models are used to process several case study which are based on previous experimental work of the Heat transfer and fluid flow laboratory. The results from case studies specify and expand the knowledge of work roll stress state. The results show the portion of each loading factor on the whole stress state. In addition, time and depth depended distribution of stress state is presented. The results from macrosferic model illustrate the cause of spalling and a rupture of the work roll. The results from the microsferic model show the cause of creation of the to-surface-parallel cracks within carbides of high chromium irons. Last chapter summarized of all results gathered from case studies together with the goals for further research definition. The necessary steps for further cognition are stated. The thesis contains a large set of appendixes with deeper discussion of several related topics. These appendixes represent the one third of whole the thesis.
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Development of industrial floors with utilization of by-product
Radějová, Lucie ; Durica,, Tibor (referee) ; Bydžovský, Jiří (referee) ; Ševčík, Milan (referee) ; Drochytka, Rostislav (advisor)
This work deals with the use of waste materials in the development of new industrial floors. The main task of this work is to choose a suitable waste materials, and design a new material using such materials, while achieving the required physico-mechanical properties. The aim of this work is also to verify the effects of process application, suitable microfiller and final coat and propose a suitable alternative industrial floors, which would not only be in terms of economic efficiency, but also in terms of ecological suitable replacement for commercial products.
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Wear resistence of cladding
Pagáč, Aleš ; Sigmund, Marian (referee) ; Kubíček, Jaroslav (advisor)
The subject of this Diploma thesis was study of wear resistant deposits, including appropriate basic and filler materials and welding technologies suitable for a particular application of hard carbide overlays of blade mixer for foundry sand. Analysis of suitable filler materials focused on extreme abrasion and select tungsten carbide hardfacing, together with a selection of appropriate overlays welding methods for welding tungsten carbide, including the conditions and parameters surfacing. The practical part deals with the design and evaluation of the experiment, three samples welding of non-alloy structural steel, tungsten-carbide hardfacing, technology MCAW - WC flux cored electrode in protective active gas.
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Coating properties of cutting tools carbide
Doležalová, Petra ; Bumbálek, Bohumil (referee) ; Osička, Karel (advisor)
Diploma thesis is divided into two parts. The first part is focused on theoretical description of coating methods, on currently used coatings, their properties and it is also focused on description of methods, which are used for analyzing each property. The second part focuses on testing of coatings and analyzing of the values obtained from experiments. The aim of this thesis is then to compare the properties of the tested coatings.
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Assessment of state banks and a proposal for stabilizing the selected dam reservoir
Kroček, Tomáš ; Pelikán, Petr (referee) ; Šlezingr, Miloslav (advisor)
This thesis covers the state assessment of the selected bank sections of dam reservoirs Vranov and Boskovice. Data used and processed in this thesis were acquired by visiting both sites several times in order to perform measurements and make photographic documentation. Futhermore, data on reservoirs' water levels from 2000-2011 provided by Povodí Moravy s.p. were used. In order to determine bank line regression, the above-mentioned data were processed using the Šlezingr's modification of the method of abrasion terminants determination. Results for dam reservoirs Vranov and Boskovice are then compared with results of dam reservoir Brno, which were produced by the author within the framework of his bachelor thesis using the same method. At the end of the thesis, the author presents several possible forms of stabilization and protection of disrupted banks of dam reservoirs, including their drawings.
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Classification and evaluation of rail wear
Nohel, Rostislav ; Frýza, Josef (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis is focused on the wear of rails. In this thesis, the reader will be firstly introduced to the fundamentals such as nomenclature of wheel and rail, adhesion, adhesion coefficient, contact area, slip, traction characteristic and wear. Subsequently, the fundamental types of material wear (adhesive, abrasive and fatigue) will be explained, which occur in the wheel-rail contact. In the next part, the individual rail defects are analysed with respect to locations. The output of the bachelor’s thesis is overview and description of the most common rail defects which are usually caused by fatigue wear.
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Evaluation of Surface Layers of Ball and Sliding Bearings Components
Šafář, Martin ; Hutařová, Simona (referee) ; Doležal, Pavel (advisor)
This bachelo’s thesis solve the problems abrasion film bearing. The purpose of this thesis was used four type film, ISOFLON, Xylan 1010, DLC a PTFE + Niborit 5P.By one of tendenci is specifi coefficient friction over tribological test. On the next tendenci was size film for and after a tribological test find, elese size abrasion. Was make chemical analyse of all film.To elements interaction study light microscopy, scanning electron microscopy equipped by energy dispersive mikroanalyses.
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Use of Bank stabilization
Neuvirt, Petr ; Pelikán,, Petr (referee) ; Šlezingr, Miloslav (advisor)
The main topic of this bachelor thesis was to suggest biotechnical stabilization on choosen locality of water reservoir Seč. This locality was endangered and damaged by abrasion. The water reservoir is situated in Pardubický region, district Chrudim. This thesis included geodetic measurement, hydrotechnical calculation and in the end of the thesis several suggestions of possible biotechnical stabilization on choosen locality.
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Stabilization of bank
Podola, Martin ; Pelikán, Petr (referee) ; Šlezingr, Miloslav (advisor)
The subject of this bachelor’s thesis is assessment of reservoir banks Bystřička in terms of abrasion. Judgement is focused on two main points on the northeastern bank of the reservoir near the tributary. It is an area near the hotel Beskydská Tatranka. Thesis is finished with design of selected biotechnical measures to slow or stop erosions banks.
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Bank stabilization of Brno Dam
Václavovský, Filip ; Pelikán, Petr (referee) ; Šlezingr, Miloslav (advisor)
The aim of this bachelor‘s thesis is to design stabilizations of the banks of the Brno‘s water reservoir, damaged by abrasion. This work is focused on the most damaged Osada area located on the left bank. Shore abrasion is caused by fluctuations in water levels and the effect of wind waves. Result of this thesis are biotechnical stabilizations, which has to stop or slow the symptoms of abrasion.
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