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Possibilities of reducing zinc losses during heat treatment of ferrite ceramics
Buday, Patrik ; Šoukal, František (referee) ; Ptáček, Petr (advisor)
The diploma thesis is focused on the study of the influence of sintering temperature on the evaporation of zinc from Mn-Zn-ferrite ceramics. The main focus of the study is on the reaction kinetics of the zinc evaporation process, at the same time the aim of this work is to propose and verify a method that would limit the evaporation of zinc. The theoretical part summarizes the basic knowledge about the properties, classification, application, and production of Mn-Zn-ferrites. The end of the theoretical part describes the loss of zinc and a possible solution to this undesirable phonomenon. The beginning of the experimental part contains a summary of the principles of infrared spectroscopy, electron scanning microscopy, and X-ray crystallography. The experimental part of the diploma thesis is focused on the description of the production of ferrite samples, the characterization of the input material and the determination of the reaction kinetics of the sintering, and its comparison with the kinetics of the sample treated with a protective layer.
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Mapping the potential of secondary products from the production of titanium white
Nehéz, Samuel Emil ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
This bachelor’s thesis deals with the use of secondary products from the production of titanium white and its subsequent use during cement production. Secondary products from the production of TiO2 could be regarded as several kinds of sulphate waters, where by their successive neutralization gypsum by-products are prepared. The aim of the bachelor’s thesis was to experiment whether it is possible to use some of these gypsum by-products as solidification retarder in Portland cement. Cement pastes were prepared and subjected to mechanical and analytical examinations. During the mechanical examinations, strength in pressure during bending and strength in pulling for the duration of 60 days were monitored. The material from tested bodies of pastes was reviewed by x-ray difraction analysis after 7 and 28 days. Just as was determined the optimum W/C, initial and final setting time. The prepared samples with the gypsum by-product as their content had some features comparable with commercially used cement.
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Recyclation of dust from production of dry mortar blends
Ondrůšková, Nela ; Novotný, Radoslav (referee) ; Šoukal, František (advisor)
The work deals with the problem of disposal of ever-increasing waste (dust) from the production of building materials and examines the possibility of recycling dust dust into cement repair mortar. The aim of this work was to determine the composition of individual dust particles from the production of cement mixtures and to determine their mechanical properties, as well as to determine the ideal ratio of dust particles to each other when mixing the dust mixture and its mechanical properties. This mixture consisted mainly of dust from products based on Portland cement, aluminous cement, gypsum and lime hydrate. The mixture further replaced part of the cementitious mortar and the impact of the additive on the mechanical properties of the cementitious mortar was determined. X-ray fluorescence spectrometry was used to determine the elemental composition, and X-ray diffraction analysis was used to determine the mineralogical composition. Test specimens were prepared according to the ČSN EN 12390 standard. Mechanical strength tests were performed on the test specimens. A large part of the test specimens could not be subjected to mechanical tests because the test specimen did not solidify even after a long time. The individual measurements that could be made show that the mechanical properties of the dust samples show values which have shown that the dust cannot be recycled into the product due to its instability. Dust particles have too diverse composition and in combination with cementitious repair mortar do not have the required properties. The problem is especially the sampling from the data, which did not solidify at all and thus excluded the remaining samples with already good properties of the same sample. When designing the method of recycling, it was necessary to take into account which product of the company is most in demand, where recycling would also make economic sense, which is also an important indicator for the operation of the company today. Dust particles could prove successful in another product, but it would not be advantageous for the company now, so now the recycling of dust particles will not start and they will be further disposed of in the same way.
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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.
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On the efficiency of plasticizing admixtures in alkali-activated slag based system
Flídrová, Michaela ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Alkali-activated materials (AAM) are construction materials with great potential, especially for their environmental friendliness, but also due to their mechanical properties. Therefore, it is appropriate to pay further attention to these binders. This diploma thesis deals with monitoring the effectiveness of plasticizers in connection with the surface chemistry of the alkali-activated slag system. Sodium hydroxide and sodium water glass were used as alkaline activators for the preparation of alkali-activated blast furnace slag-based systems. To study the effectiveness of the lignosulfonate plasticizer, yield stress, heat flow, adsorption and zeta potential were monitored depending on the amount and time that the plasticizer was added to the system. The results show that the type of activator used in the mixtures plays an important role. NaOH-activated samples revealed the best efficiency of lignosulfonate plasticizers. A key factor in studying the behavior of the studied mixtures was the measurement of the zeta potential, which provided insight into the surface charge of blast furnace slag particles related to the ability of lignosulfonate to adsorb on grains of alkali-activated slag.
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The study of hydration of RPC (Reactive Powder Concretes) in hydrothermal condition
Dvořáková, Tereza ; Koplík, Jan (referee) ; Šoukal, František (advisor)
The diploma thesis deals with the study of hydration of reactive powder concrete under hydrotermal conditions. The theoretical part describes the properties of materials and additives used for the preparation of mixtures. The following describes the principles and requiments for the materials for preparing the reactive powder concrete. The practical part is studied design method mix and the impact of materials to the consistency of paste. The effect of cample placement on flexural and compressive strength of the prepared mixtures was observed. The samples were stored under standart laboratory conditions and under hydrothermal conditions. The phase composition of the samples was monitored by X-ray diffraction analysis and the mocrostructure by scanning electron microscopy.
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Surface treatment of cementitious systems by silicate sealers
Iliushchenko, Valeriia ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Impregnace na bázi silikátů se široce používá k ochraně betonu před agresivním prostředím. Pochopení aspektů týkajících se tohoto typu impregnace však není zcela jasné. Tato práce představuje informaci o jednotlivých vlastnostech vybraných křemičitanů, přesněji draselného, sodného, lithného a koloidního oxidu křemičitého (koloidní silika), dále o účinnosti z hlediska nasákavosti, stupni účinku na hydrataci cementu, schopnosti těchto látek uzavřít póry a jejích vliv na mikrostrukturu cementového substrátu a na penetrační schopnost. Účinnost filmotvorných látek byla hodnocena jak na čerstvém cementovém tmelu, tak na vyzrálejším, aplikovaných po 1 a 24 hodinách od smíchání směsi. K dosažení kvalitativních výsledků byly použity instrumentální metody, jako je rtuťová porosimetrie, rheometrie, izotermální kalorimetrie, rentgenová difrakční analýza a skenovací elektronová mikroskopie. S ohledem na provedené testy byla prokázána určitá účinnost ošetřujících přísad. Výsledky všech testů ukázaly vyšší účinnost těchto látek v případě ošetření na vyzrálejším cementovém povrchu, což bylo pravděpodobně způsobeno vyšším stupněm hydratace, díky čemuž se vytvořily nové fáze, se kterými silikáty byly schopné zareagovat a jistým způsobem ovlivnit mikrostrukturu.
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Oxidative passivation of metal powder
Kuna, Petr ; Solný, Tomáš (referee) ; Šoukal, František (advisor)
This thesis deals with the study of the effect of the oxide layer on the surface of metal powder on selected properties of fuel-oxidizer pyrotechnic system. Research includes finding optimal thickness of the oxide layer with using XPS and SEM methods, its conditions of formation and its influence on pressure-time curve and to resistance to ESD.
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Magnetic classification of fly ashes and application of products
Červený, Ľuboš ; Švec, Jiří (referee) ; Šoukal, František (advisor)
Submitted bachelor thesis is dealing with problematics of magnetic separation of fly ash and utilization of the products of the separation in production of refractory ceramic materials. High temperature fly ash from power station Mělník was used in this thesis.Thesis evaluates results of magnetic separation at different setting of magnetic separator. It proves, that fraction of particles rich in iron as well as fraction depleted by this iron can be obtained by magnetic separation. In this thesis are presented results of volumetric weight, mineralogic element composition, measurments by heating microscope and results of particle size distribution of unseparated fly ash, but also its both separates. The thesis is focusing on possibilities of utilization as additive in refractory ceramic materials and comparison of their refractory properties. It evaluates results of characterisation of the products using XRD analysis and scanning electron microscopy.
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Monitoring of alkalis in Portland clinker
Siudová, Alena ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis focuses on the localization of alkali in Portland clinker and their properties, which can significantly affect the lifetime of the concrete produced from these cements. The bachelor thesis deals with the study of the phases of the alkali in Portland clinker and the compounds they represent. Further, the bachelor thesis deals with the study of the rate of transfer of alkali into solution when mixing Portland clinker with water. Several different Portland slinks are analyzed and compared. The aim of the thesis is to try to find a connection between measured experimental values, clinker composition and alkaline-silica reaction precursors.
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