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Mechanical Properties of Microstructural Components of Inorganic Materials
Wasserbauer, Jaromír ; Palou, Martin (referee) ; Drábik,, Milan (referee) ; Havlica, Jaromír (advisor)
Disertační práce se zabývá studiem strukturních a mechanických vlastností anorganických materiálů. Cílem je nalezení jednotlivých fází ve zkoumaném materiálu a hlavně lokalizace (mechanicky) nejslabšího místa, jeho ovlivnění a následně výroba materiálu o lepších mechanických vlastnostech. Z důvodu velkého množství použitých metod je základní teorie vložena vždy na začátku příslušné kapitoly. Taktéž z důvodu značného množství výsledků jsou na konci kapitol uvedeny dílčí závěry. Práce je rozdělena na tři části, kdy první se zabývá seznámením s možnostmi modelování mikro-mechanických vlastností a provedením experimentů umožňujících posouzení rozsahu platnosti některého modelu. V druhé části je provedeno shrnutí současných možností indentačních zkoušek pro měření mechanických vlastností strukturních složek betonu a praktické zvládnutí metodiky vhodné k užití pro výzkum materiálů zkoumaných domovským pracovištěm. V třetí části je navržena metoda identifikace nejslabších článků struktury anorganických pojiv a její ověření na konkrétním materiálu zkoumaném na domovském pracovišti. V této dizertační práci jsou použity tyto metody: kalorimetrie, ultrazvukové testování, jednoosá pevnost v tlaku, nanoindentace, korelativní mikroskopie a rastrovací elektronová mikroskopie s energiově disperzním spektrometrem. Dílčími výsledky jsou kompletní charakterizace cementových materiálů, upřesnění stávajících poznatků a nalezení optimálního postupu pro charakterizaci. Hlavním výsledkem je inovativní přístup vedoucí k pozitivnímu ovlivnění materiálu.
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Meta-talc Application in Inorganic Materials
Bednárek, Jan ; Rovnaník, Pavel (referee) ; Palou, Martin (referee) ; Havlica, Jaromír (advisor)
This thesis is focused at possibilities of preparation and characterization of XRD-amorphous delaminated and dehydroxylated talc phase – meta-talc, which can have its potential application and a starter material for a preparation of magnesium-silicate analogues of geopolymers. Changes in structure and morphology of talc ore were observed during this work. For the purposes of this research, two various talc ores – chloritic and dolomitic were examined. Whole process of meta-talc preparation was examined with whole scale of instrumental techniques such as X-ray diffraction, simultaneous thermogravimetric a differential thermal analysis, infrared spectroscopy, scanning electron microscopy or laser analysis of particle size. Meta-talc can be obtained via mechanochemical activation of talc ore with subsequent calcination. Mechanochemical treatment lead to destruction of original crystal structure and breaking of original bonds, i.e. the product of this treatment was almost amorphous and delaminated. Most of hydroxyl groups were converted to molecules of water which remained adsorbed or coordinated in ore structure. These molecules were removed during calcination step.
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The influence of barium and its compounds on the formation and properties of Portland clinker
Zezulová, Anežka ; Rovnaníková, Pavla (referee) ; Palou, Martin (referee) ; Ptáček, Petr (advisor)
The work deals with the study of barium cement. Barium cements are used to prepare concrete that protects against ionizing radiation. Barium can be also present in a conventional Portland cement clinker as an impurity from alternative fuels or raw materials, which are increasingly used for clinker production, and thus change the structure and properties of the product. Various methods of preparation of this cement were studied in this work. Barium cements were prepared from raw meals of different composition, but always with the same procedure and burning temperature. Using suitable analytical methods, the work describes the influence of individual admixtures of raw meal on the phase composition of the resulting clinker. Furthermore, the work deals with monitoring the form and location of barium in the prepared clinker. Several experiments are focused on the study of hydration of prepared barium clinkers, the phase transformation is monitored by XRD and supplemented by analyses of hydration products. In this way, it was possible to obtain the data needed to describe the preparation, burning, and hydration of barium cements with different compositions. The work also deals in detail with the real use of barium cements. The ability of pastes and mortars from prepared barium cements to shield various types of ionizing radiation was tested and described experimentally. The results are presented in comparison with reference samples, which were prepared from commonly used Portland cement.
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Synthesis of foamed bioceramics for potential medical applications
Doboš, Petr ; Šoukal, František (referee) ; Palou, Martin (advisor)
Cílem práce byla příprava porézních vzorků HAP pro potenciálně medicínské aplikace. HAP byl připraven metodou sol-gel a precipitační. Vzorky HAP byly podrobeny analýze FTIR, XRD, SEM. Takto připravený HAP byl napěněn pomocí houbové metody s jasně definovanými póry a pomocí polymerního a skleněného expanzelu s různou distribucí a velikostí pórů. U výsledných napěněných vzorků byla vyhodnocena mikrostruktura a povrchová analýza pomocí SEM, zjištěna porozita pomocí Hg porozimetru a sledována bioaktivita in vitro v SBF. Byly zjištěny jasně definované makro, mezo a mikro póry při různé distribuci. U houbové metody pomocí sol-gel došlo k vytvoření jasně definovaných a pravidelných pórů s monodisperzní porozitou. Dominantní velikost póru byla stanovena v rozmezí 1–5 µm. Celková porozita byla stanovena na 63,5 % s celkovým povrchem 3,048 1 m/g. Precipitační metodou s polymerním expanzelem došlo k polydisperznímu rozložení pórů s třemi hlavními fázemi v rozmezí: 50–100 µm, 5–10 µm a 0,5–1 µm. Celková porozita byla stanovena na 67,6 % s celkovým povrchem 19,090 3 m/g. Bioaktivita výsledných napěněných vzorků in vitro byla sledována po dobu 7 dnů v připraveném SBF. Při napěnění sol-gel houbovou metodou nevznikla výsledná bioaktivní vrstva. U precipitační metody napěněné pomocí polymerního expanzelu vznikla nepravidelná bioaktivní vrstva. Výsledky byly naměřeny pomocí SEM analýzy.
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Preparation of bioceramic materials for medical applications
Doboš, Petr ; Šoukal, František (referee) ; Palou, Martin (advisor)
The aim of this work was to prepare hydroxyapatite powder by sol-gel and precipitation method. Then, the powders were pressed and sintered at 500 °C, 800 °C and 1100 °C. These samples of HAP were analyzed by FTIR, XRD, SEM methods. The microstructure measurement by SEM indicates that the size HAP particles varies from micro to nano meter. The average size of dominant particles is determined around 5 – 8 µm with surrounding fine particles of 1 µm size. The in vitro bioactivity of HAP samples was investigated by immersing them in Simulated Blood Fluid for 4 weeks. The work reports the result of mikrostructure analysis of samples after immersion. The bioactivity was influenced by the sintering temperature. It is evident, that the layer of the new hydroxyapatite phase formed during immersion on the surface of initial HAP samples changes with temperatures.
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Application of Sol-Gel Method for Preparation of Dicalcium Silicate and its Solid Solutions
Baráček, Jan ; Živica, Vladimír (referee) ; Rovnaníková, Markéta (referee) ; Palou, Martin (advisor)
The subject of this doctoral thesis was to elucidate the mechanism of reaction leading to the formation of dicalcium silicate (C2S), its solid solutions and other phosphatic calcium silicate phases using the sol-gel method of synthesis. SiO2 (Tosil A), CaO (calcium nitrate tetra-hydrate) and H3PO4 (as a source of P2O5) were used as starting materials. Series of samples with different content of P2O5 were synthesized. The characterization of Tosil A and samples was based on the following methods: DTA/TGA and EGA, XRD and SEM and EDS analy-ses. It is known, that phosphorous oxide can enter the structure of C2S and possibly form solid solutions and different phosphatic calcium silicate phases in C2S–C3P system. Depending on the P2O5 concentration in mixtures, three distinct phases are formed: larnite (2CaO•SiO2), Ca14,92(PO4)2,35(SiO4)5,65 and 5CaO•SiO2•P2O5, as detected by XRD. Local microanalysis de-monstrated the presence of calcium phosphate epicenters (C3P) containing SiO2, calcium sili-cate (C2S) zones with minimum content of P2O5 and intermediary areas of various phosphatic calcium silicates. The formation of two distinct islets of C2S and C3P is due the affinity of acid oxides (SiO2, P2O5) towards the basic one (CaO) during the sol-gel process. Then, the formation of various phosphatic calcium silicates results from the diffusion of P2O5 and SiO2 towards calcium silicate and calcium phosphate, respectively.
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Preparation and Properties of Roman Cement
Opravil, Tomáš ; Palou, Martin (referee) ; Škvára, František (referee) ; Havlica, Jaromír (advisor)
The Ph.D. thesis deals with the preparation of highly hydraulic binders based on roman cement. Roman cement (natural cement) is recently not available on the market due to uneconomic production of such a specific binder. On the other hand there is a big lack of information on this hydraulic binder. These results in failure in meeting the basic principle of modern approaches to restoration of historical buildings or monuments made of such kind of materials, which is such, that the materials used for restoration should be compatible with original material. Recognition of the processes of roman cement preparation based on progressive methods of study can provide substantial information for more efficient raw material selection or even for nontraditional utilization, for example for artworks. This work hence is aimed at studying and selection of traditional natural as well as nontraditional raw materials such as clay. This work also studies the preparation of highly hydraulic binders based on roman cement and the kinetics of burning and hydration processes
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SYNTHESIS AND DETERMINATION OF PROPERTIES OF PURE PHASES OF PORTLAND CLINKER AND THEIR POLYMORPHS
Ravaszová, Simona ; Keppert, Martin (referee) ; Reitermann, Pavel (referee) ; Palou, Martin (referee) ; Dvořák, Karel (advisor)
Quantitative diffraction analysis is currently carried out through Rietveld analysis, which is able to decode the various diffraction lines on a diffraction record, provided that the structural model for each clinker phase is well known. The subject of this dissertation is the laboratory preparation of pure phases of one triclinic and two monoclinic polymorphs of the main clinker mineral alite, which will serve as standards for the calibration of powder X-ray diffraction analysis. The result of this work will be detailed procedures for the preparation of individual polymorphs of alite and calibration relationships for unambiguous and easier identification of monoclinic polymorphs in real clinkers.
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The influence of barium and its compounds on the formation and properties of Portland clinker
Zezulová, Anežka ; Rovnaníková, Pavla (referee) ; Palou, Martin (referee) ; Ptáček, Petr (advisor)
The work deals with the study of barium cement. Barium cements are used to prepare concrete that protects against ionizing radiation. Barium can be also present in a conventional Portland cement clinker as an impurity from alternative fuels or raw materials, which are increasingly used for clinker production, and thus change the structure and properties of the product. Various methods of preparation of this cement were studied in this work. Barium cements were prepared from raw meals of different composition, but always with the same procedure and burning temperature. Using suitable analytical methods, the work describes the influence of individual admixtures of raw meal on the phase composition of the resulting clinker. Furthermore, the work deals with monitoring the form and location of barium in the prepared clinker. Several experiments are focused on the study of hydration of prepared barium clinkers, the phase transformation is monitored by XRD and supplemented by analyses of hydration products. In this way, it was possible to obtain the data needed to describe the preparation, burning, and hydration of barium cements with different compositions. The work also deals in detail with the real use of barium cements. The ability of pastes and mortars from prepared barium cements to shield various types of ionizing radiation was tested and described experimentally. The results are presented in comparison with reference samples, which were prepared from commonly used Portland cement.
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The composition and physical-mechanical properties of self consolidating mortars
Čepčianska, Jana ; Bílek, Vlastimil (referee) ; Palou, Martin (advisor)
This Master thesis is focused on characterization of multicompound self-compacting heavy-weight mortars resistant against long lasting influence of ionizing radiation in the underground nuclear waste storage. It examines a specific combination of properties of heavy-weight concretes and self-compacting mortars while considering the ecological and energetic impact of their production, as well as the productibility of partial substitutions that do not have negative impact on material properties. The Experimental part provides a comprehensive overview of composition and properties of self-compacting heavy-weight mortars with varying percentages of cement-to-mortar ratio. Sample properties were evaluated based on mechanical test results, thermal analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction.
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