|
|
Preparation of calcium-aluminate phases
Ohaňka, Zdeněk ; Novotný, Radoslav (referee) ; Koplík, Jan (advisor)
This work focuses on the preparation of calcium aluminates by solid state synthesis and by sol-gel method. Phases prepared were monocalcium aluminate (CA), dodecacalcium heptaaluminate (C12A7), tricalcium aluminate (C3A) and calcium dialuminate (CA2). Two modifications of sol-gel method were used – the difference between them was in the addition of EDTA. Each method was closely described and results were compared according to the achieved purity of prepared phases. X-ray diffraction analysis was used to determine the purity of prepared calcium-aluminates.
|
|
|
Morphology of Polyamide 12 and Polyamide 11 formed at overpressure and underpressure
Bělašková, Marie ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
In this master thesis it was studied morphology of polyamide 12 (PA12), polyamide 11 (PA11) and their blends in the percent ratios 95/5, 75/25, 50/50, 25/75 and 5/95 formed at pressure 7 MPa in a calorimeter both after continual heating and cooling and after annealing and isothermal crystallization. Neat polyamides and blends were further characterized by thermogravimetric analysis, differential scanning calorimetry at atmospheric pressure, Fourier-transform infrared spectroscopy in attenuated total refection, and X-ray diffraction analysis. The increased pressure improved level of polyamide chains ordering in crystal lamellae. Thermal annealing improved especially ordering of PA12, isothermal crystallization led to considerable increase of crystallinity, whereas PA11-rich blends supported perfection of PA12 crystals. Partial transformation of - to -structure occurred in case of neat PA12 at high pressure, the change of the chain conformation into the closer one occurred in neat PA11 without transformation of the type of crystal structure.
|
|
|
Study of microstructure of autoclaved aerated concrete with using of secondary raw materials
Martanová, Jana ; Suchý, Peter (referee) ; Kulísek, Karel (advisor)
Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.
|
|
|
Study of particles of various cosmetic pigments
Cerevatova, Kristina ; Opravil, Tomáš (referee) ; Zemanová, Jana (advisor)
The main focus areas of this master thesis include the writing of a literature review, which contains an overview and segregation of pigments which are used in the preparation of cosmetic products. The thesis is focused on the properties and characterization of pigments for use in cosmetology. The following focus is on legislation, more specifically on pigments that the cosmetic industry allows, limits and does not allow. The main part of this thesis is an overview of methods for the characterization of pigments. The practical part deals with the characterization of particles of selected cosmetic pigments by applying methods for determination of color, elemental and phase composition, particle size and morphology. The thesis is concluded by evaluation of the achieved results.
|
|
|
Mineralogical composition of silica brick.
Pospíšil, Dušan ; Kotouček, Miroslav (referee) ; Nevřivová, Lenka (advisor)
This Bachelor´s thesis deals with the mineralogical composition of dense silica bricks. Silica bricks is a siliceous refraktory material that contains up to 99% of silicon dioxide, which is used mainly for the construktion of coke oven batteries, glass furnaces and heaters of blast-furnace wind. The main emphasis in case of silica bricks is put on the content of crystalline phases, which are the residual untransform quartz, tridymite, cristobalit and glass phase. These stages affect the resulting properties of dinas substantially. The main goal of this Bachelor´s thesis is to evaluate the impact of firing on the mineralogical composition of silica bricks and to its dilation at elevated temperatures.
|
|
|
Forsteite and the Possibilities of its Synthesis
Nguyen, Martin ; Keršnerová, Lucie (referee) ; Sokolář, Radomír (advisor)
The aim of this Bachelor thesis is to characterize the most important properties of forsterite and its practical use. Theoretical part contains characteristics of individual raw materials, which are used for synthesis of forsterite and the assessment of raw material possibilities of Czech Republic for the production of forsterite. The main focus is placed on the detailed research of published results of the most used technologies for synthesis of forsterite. At the end of theoretical part is the design of the most suitable production technology for forsterite in the Czech Republic. The practical part verifies suggested design of the production technology for forsterite synthesis together with a comparison of basic parameters of laboratory prepared forsterite with published parameters. X-ray diffraction analysis will be used for the evaluation of purity of the synthesized forsterite.
|
|
|
Structural and morphological characterization of polyamide buckles
Kubíčková, Eva ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
The work deals with structrural and morphological characterization of polyamide buckles used to fasten webbins. The buckles were produced in five different years, a few of those produced in 2000 and 2004 were broken. The aime is to determine the type of polyamide and the cause of fracture of the buckles during using. The buckles were characterized in terms of structure and composition by Fourier-transform infrared spectroscopy in a mode of attenuated total reflaction, differential scanning calorimetry, thermogravimetry and X-ray diffraction. The buckles were made of polyamide 12. The broken buckles showed higher melting point, lower thermal stability and, in addition to modification it also contains modification, which is more fragile and probably represents the cause of fracture.
|
|
| |
|
|
Characterization of heat treated Ni-P coatings with different phosphorus contents.
Žilinský, Martin ; Kosár, Petr (referee) ; Wasserbauer, Jaromír (advisor)
The aim of this work was the characterization of heat–treated, electroless nickel–phosphorus coatings of different phosphorus content. In the theoretical part of this work, the substrate for the nickel–phosphorus coating, namely the AZ91 alloy, is discussed. Further, the deposition of the nickel–phosphorus coating on the substrate, the components of the nickel baths and their influence on the phosphorus content of the deposited coating nickel–phosphorus, is analyzed. Attention is also paid to the structure of this coating depending on the phosphorus content. Heat–treatment and its influence on the hardness of this coating is also discussed. At the end of the theoretical part, the current research in the field of nickel–phosphorus coatings, is described. The experimental part of this work describes the pre–treatment of samples and their characterization. Using a scanning electron microscope, the phosphorus content of the heat–treated coatings was determined. Furthermore, the microhardness of heat–treated nickel–phosphorus coatings was measured. X–ray diffraction analysis determined microstructure and crystallite size of the phases present in coatings after heat–treatment.
|
|
|
Refractory Products for Aluminum Metallurgy Industry
Kupcová, Zuzana ; Lang, Karel (referee) ; Nevřivová, Lenka (advisor)
The master´s thesis focuses on high-alumina refractory materials used mainly in aluminia metallurgy. Teoretical part of this thesis is aimed at distribution of refractory materials, possibilities of its production and raw material basis. Characteristic properties are described as well as application possibilities in aluminium technology. In final part of this thesis experimental data are evaluated to obtain physical, mechanical, chemical properties of high-alumina refractory materials. Those are used for economical optimalization of raw materials.
|
guest ::
