|
|
Enamels containing recycled brick waste
Tmejová, Jana ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
The diploma thesis deals with the possibilities of using recycled brick as a component in the preparation of glazes. Recycled brick is a mixture of crushed bricks, it can also contain a brick tablecloth, its composition and color makes this material practically identical to a brick shard. Due to these properties, it can be assumed that recycled brick can be used to prepare technical glazes with a specific color. The aim of the diploma thesis is to verify the possibilities of using recycled brick for the preparation of technical glazes. For prepared glazes, then evaluate their properties and estimate for which type of product these alternative glazes could be used.
|
|
|
EXPERT ANALYSIS OF SELECTED PROBLEMS SEEING PEDESTRIANS BY VEHICLE DRIVER IN VISIBILITY REDUCED BY DARKNESS
Sedlák, Jaroslav ; Kropáč, František (referee) ; Drahotský, Ivo (referee) ; Ptáček, Petr (referee) ; Bradáč, Albert (advisor)
The dissertation is focused on the problematic of the driver´s ability to see pedestrians in the conditions of driving at night. The first part tells the current view of these problematic, terms are defined: the outlook and the range of vision to see the obstacle. This part also describes various effects that are affecting the driver´s ability to see pedestrians while driving at night. Out of all mentioned effects, this project mainly focuses on two parameters – how is the driver´s ability to see a pedestrian affected by his obsolence and developing visual handicap. During the research, high number of respondents of wide range of age and various vision quality were present and attended the experiment. This project proposes a methodology of comparasion of those two parameters mentioned above. The main condition which must have been held was to create absolutelly identical conditions of the experiment used by wide range of respondetns. The best way how to possibly achive the best results is by using a video scene on the PC monitor. Two sets of photographies were made while preparing the experiment (2 various sets of clothes for the pedestrian) and these sets were sorted by using the Microsoft Office Power Point program. This made a simulation of a vehicle approaching a pedestrian at night. The measurement was attended by a large number of respondents who were divided into a total of nine categories, according to age and extent of ocular defects. The dissertation is a methodology for evaluating the measurements, determination of contrast and angular size of the watched object (pedestrian) using the scene on the PC monitor. At the end of the experiment is an evaluation of the measurements and put comments on the results obtained. This project proposses a method for the early detection of the driver´s perception when sighting barriers (pedestrian) using the electrophysiological examination method – the electroretinography (ERG). In this dissertation,the initial measurements were carried out using this method, when during the measurement was unfortunately found that the sensitivity of the method does not allow resolution changes of the electrical potential for so little intense stimuli such as the sight of pedestrians at the edge of the road. But it is not excluded that in the future the further development of the ophthalmological diagnostic method will increase the sensitivity so it will allow to spot the objective moment of registration the obstacle by the viusal organ
|
|
|
Utilization of mica separated from washed kaolin
Vaculík, Josef ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
The Master’s Thesis aims to laboratory test the possibilities of utilization mica separate, which arises during the process of floating kaolin as a by-product together with sand. Mica and sand are then separated by flotation or vibration. The mica separate thus formed was subjected to analysis. XRD and heating microscopy methods were used for analysis. Subsequently, experiments with mica separation as a filler in composites based on epoxy resins were set up and performed. Furthermore, the separate was tested as a part of plasters and visual building elements. Last but not least, the separate was mixed into the ceramic, which was then subjected to firing in the selected mode. The diploma thesis provides a comprehensive overview of the above-mentioned possibilities of using mica separation, which is based on a sufficient amount of experimental data.
|
|
|
Influence of zinc loss during the sintering on permeability/inductance of ferrite ceramics
Kvapilová, Vendula ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
The diploma thesis is focused on the investigation of the effect of zinc release during ferritic sintering on the permeability/inductance of ferrite ceramics. The theoretical part deals with the position of ferrites among other ceramic materials. It describes the basic characteristics of ferrites, their crystal structure and finally the problems that are directly related to their production and which fundamentally affect the magnetic properties of ferrites. In the second part of the work, the influence of the temperature and time of sintering and the position of the cores in the furnace during firing on the loss of zinc from the sample and subsequently on the electromagnetic properties of the prepared test specimens from industrial raw material mixtures was investigated. These are initial experiments, which will be followed by further research aimed at eliminating the problem of zinc loss in the production of Mn-Zn ferrites.
|
|
|
Influence of noble earth's elements on Bi based high temperature superconductors phase transition
Snopek, Jan ; Havlica, Jaromír (referee) ; Ptáček, Petr (advisor)
The Bi2Sr2CaCu2O7+d, i.e. Bi2212 phase of bismuth derived high temperature superconductors (HTS), powder precursor were synthesized via sol – gel technique using ethylendiamintetraacetic acid (Chelaton II) as a chelating agent. Metal nitrate’s solutions were mixed with EDTA suspension. The pH value was adjusted to 9 by NH4OH by reason forming of stable metal’s complexes. The mixture was heated to 80 °C for gelation. Solution taken before solid gel was form is used for preparation of Bi2212 layer on to a-Al2O3 surface via spin coating deposition’s technique. Reactive powder used for bulk sample preparation was made by calcination (800 °C) of pyrolyzed xerogel (500 °C). Sintering in oxygen atmosphere was proceeding at temperature from 850 to 880 °C. Bulk sample properties were compared with sample prepared by common ceramic method. Simultaneous TG-DTA, IR spectroscopy and heating microscopy were used for sample characterization. Furthermore, construction of furnace for sintering in O2 atmosphere was described.
|
|
|
Modification of dry stuff with lime sludge
Švec, Jiří ; Kovářová, Alena (referee) ; Ptáček, Petr (advisor)
In modern point of view of waste management is desirable to effectively process the grates possible amount of wastes. Sediments from cleaning of mined lime stones contains a lot of clay components, but there is also indispensable share of soft calcite. Especially this can be use in following processing. After firing, where is necessary to set suitable temperature, arises a mixture of soft calcinated lime and remaining dehydrated mineral components. This calcinated mixture could partially replace used binders in dry stuffs.
|
|
|
Hydration Process of Magnesium Oxide from Partly Calcined Dolomite
Tišnovský, Michal ; Bartoníčková, Eva (referee) ; Ptáček, Petr (advisor)
This bachelor thesis deals with the study of half-burnt dolomite, it‘s thermal decomposition (calcination) and preparation of a mixture of magnesium hydroxide and calcium carbonate by precipitation. At the beginning of the experimental part, the dolomite material sample is characterized. It‘s moisture content, double magnesium carbonate content and other carbonates are found. The second part deals with the study of the burning process in which a suitable interval of thermal treatment temperature was found. The investigation of the dissolution of dolomite in hydrochloric acid revealed the reaction kinetics. For precipitation, a method based on boiling a dolomite suspension in a hydrochloric acid solution under reflux, was used. The precipitation product in this case was magnesium carbonate in the modification of aragonite.
|
|
|
Corrosion protection of magnesium alloys
Minda, Jozef ; Ptáček, Petr (referee) ; Zmrzlý, Martin (advisor)
This work deals with an alternative procedure to conventional surface treatment of magnesium alloy AZ31 and AZ91 by fluoride coating layer. Synthesis of fluoride layers was carried out in the melt of NaBF4, while were following coating properties depending on the set process parameters, particularly temperature. The evaluation of coating were used scanning electron microscopy (SEM), light microscopy (LM) and immersion tests in 3.0% NaCl solution of 1, 8, 24, 48 h addition was carried out a short immersion test, in the strongly corrosive 70% HNO3. The coating was analyzed by energy dispersive spectroscopy (EDS or EDX) to determine the chemical composition. Tests showed very good corrosion resistance and showed that in this way, a reproducible compact coating was formed. The analysis identified a layer of stechiometric compounds MgF2 and NaMgF3. At the same time was the current research in the field of corrosion protection of Mg alloys. The prepared coating was confronted with current technology and in conjunction with searches were designed options such research can continue this kind of coating proceed.
|
|
|
Dissolution of silicates for carbon dioxide mineral storage
Křečková, Magdaléna ; Havlica, Jaromír (referee) ; Ptáček, Petr (advisor)
The degradability of wollastonite, montmorillonite and talc in an aqueous solution of acetic acid at different temperatures is main object of this study. Mineral carbonation, i.e. the reaction of calcium and magnesium presented in these three silicates, is a novel and promising approach to carbon dioxide capture and long-term storage. The kinetic of wollastonite, montmorillonite and talc dissolution is studied due to assessment of their efficiency for CCS technologies. The dissolution kinetic is discovered with using measured time dependence of Ca2+ and Mg2+ leached ions concentration.
|
|
|
The study of degasing process during thermal treatment of advanced ceramic
Kocián, Karel ; Šoukal, František (referee) ; Ptáček, Petr (advisor)
This bachelor thesis deals with mechanism and kinetics of the burnout of additives during thermal treatment of ferrite ceramics. In order to establish this process thermal analysis were used, specifically: simultaneous thermogravimetric determination, differential thermal analysis and thermal analysis with evolved gas analysis (TG-DTA and EGA), high-temperature microscopy (HM), burning test in kiln with controlled atmosphere and high-temperature X-ray diffraction (HT-XRD). To determine the elemental composition after sintering and characterization of the sample, scanning electron microscopy (SEM) was used.
|
guest ::
RSS feed.