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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.
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The Combustion of Organic Lightweighting Agents in the Chamotte Materials
Smékalová, Veronika ; Keršner, Štěpán (referee) ; Sokolář, Radomír (advisor)
Lightweight chamotte products are popular building material. There are many types of lightweight chamotte on the market, but the most popular lightening options are organic ingredients. This brings some problems to the production of these products. This thesis deals with the burning of various types of lighters from shards of fireclay materials. In the theoretical part are summarized raw materials, which are necessary for production of lightweight chamotte. The results of the published research studies on the topic of lightening of organic lightening products are being described here. The practical part deals with properties of products made of clay or kaolin with the addition of a certain amount of lighter. These added lighters are spruce sawdust, beech sawdust, peat, bran, paper slurry and anthracite. All these lighters are direct. For comparison, the cenospheres, which represent indirect lightweights, were also included in the research. For all specimens, the temperature interval of burnout of specimens, refractoriness, classification temperature, bulk density, thermal conductivity coefficient and other properties were defined.
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Polymer-cement composites of increased refractoriness
Žůrová, Marcela ; Mončeková, Miroslava (referee) ; Šoukal, František (advisor)
The subject of the barchelor thesis is the preparation of high-strength polymer – cement composites based on the calcium aluminate cement and polyvinylalcohol. For macrodefect–free (MDF) composites are characterized by low porosity and the absence of microcracks. The main problem of the MDF composites is decreased resistance to water or moisture, with a decrease in strength. These compounds are interesting with its mechanical properties, which are greater than the strength of common materials (wood, glass, PMMA,…). Represent perspective type of material that could be used for construction purposes. The thermal degradation of the polymer, however, there are changes in the structure of the composite and to the deterioration of mechanical properties. This thesis is focused on characterization of the effect of temperature change on the structure, material composition and mechanical properties. The MDF composites were prepared based on calcium aluminate cement, which was gradually replaced by refractory additives. During the work was carried out tests of bending strength at various temperatures. Changes in the composition and structure were characterized by TG – DTA, XRD and SEM analysis.
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Actual trends in manufacturing of ceramic shell moulds
Jankůj, Luděk ; Soukupová, Lucie (referee) ; Horáček, Milan (advisor)
Final thesis deals with the properties and production of ceramic shell moulds for investment casting method. Literature search focuses on the core of the production this mould used for ceramic and refractory slurry spreading. Attention is also paid to the technology of its production, testing ceramic shell mould and defects caused by improper manufacturing process forms. Another part of the work is focused on current trends in the production of ceramic shell moulds. The last part describes the production of ceramic shell mould in the company Česká zbrojovka. The conclusion summarizes information of production and the recommended choice of materials and manufacturing processes for ceramic shell moulds for the issue.
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The Effect of Production Technology on the Properties of Forsterite
Nguyen, Martin ; Keršnerová,, Lucie (referee) ; Sokolář, Radomír (advisor)
The main objective of this thesis is to evaluate the effect of production technology on the properties of forsterite. The theoretical part contains the fundamental parameters and the use of forsterite in the industry together with various possibilities of forsterite production. The main emphasis is placed on the characteristics of the raw materials for production as well as the raw materials possibilities of the Czech Republic. The end of the theoretical part contains a design for the production technology of forsterite, which will be verified in the practical part. The practical part verifies the use of various raw materials for the composition of the raw material mixture. The created test specimens were subjected to the X-ray diffraction analysis, the determination of tensile bending strength, thermal conductivity coefficient, apparent porosity, bulk density, apparent density, water absorption, permanent change in dimension on heating, refractoriness, thermal expansion coefficient, refractoriness under load and the thermal shock resistance. At the end of the practical part is the verification of the design of the production technology of forsterite.
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Influence of chemical composition of steel on structure and properties of stainless steels
Valenta, Pavel ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
The thesis is focused on high-alloy austenitic and austenitic-ferritic (duplex) steel. The theoretical part includes research about high-alloy steels and basic introduction to this issue. In the practical part of the test there were casted refractory austenitic steel 30CH3N17G2L, duplex stainless steel 1.4462, low carbon steel and high carbon steel. On the castings of austenitic steel were made mechanical and technological tests. There were evaluated the effects of different casting temperature and casting wall thickness to the microstructures and macrostructures of steel, tensile strength and charpy impact tests. The technological tests compared technological properties of these steels.
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Polymer-cement composites for refractory aplications
Zbončák, Marek ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
This bachelor thesis deals with preparation of high-strength polymer-cement composites based on the calcium aluminate cement and polyvinylalcohol. MDF composites are interesting because of their mechanical properties which exceed strengths of the common materials based on the cement and inorganic binders. So they represent perspective kind of material which could be used for construction purposes. Thermal degradation of the polymer leads to structure changes of the composite and reduction of mechanical properties. Therefore thesis is aimed to characterize the influence of the temperature on mechanical properties, structural changes and material composition. Temperature dependence of flexural strength was examined during the work. Changes of composition and structure were characterized by XRD, DTA-TGA in combination with EGA, SEM and EDS analyses. Due to requirement of the material refractoriness there were also tested options of preparation of MDF composites based on phosphates binders which are used in refractory manufacture.
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Synthesis of multiphase forsterite–spinel ceramics with improved properties
Nguyen, Martin ; Keršnerová, Lucie (referee) ; Nevřivová, Lenka (referee) ; Vejmelková, Eva (referee) ; Sokolář, Radomír (advisor)
This doctoral thesis is concerned with the synthesis of multiphase forsterite–spinel ceramics with improved properties in comparison with conventional forsterite ceramics. The objective of this work was to optimize the designed raw material mixtures in dependence on the production technology and resulting parameters, particularly in terms of phase composition, microstructure and refractory properties. The results of the research demonstrated an improvement in thermal shock resistance and modulus of rupture as a result of the synergistic effect of the individual phases in terms of the microstructure. In the end, the industrial applicability of the selected mixtures was verified by the corrosion resistance testing against several materials.
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Corrosion Resistance and Microstructure of Refractory Forsterite-Spinel Ceramics
Nguyen, Martin ; Sokolář, Radomír
This article examines the process for the synthesis of forsterite–spinel refractory ceramics utilizing fly ash and reactive alumina as raw materials. Raw materials were pre-treated, mixed, and sintered at 1 550 °C for 3 h. Sintered samples were characterized by XRD and SEM. Porosity, water absorption, bulk density, refractoriness, refractoriness under load, thermal shock resistance and corrosion resistance by iron and clinker as corrosive media were also investigated. The impact of different raw material mixtures was investigated in accordance with the resulting properties, microstructure, and corrosion resistance of all fired samples. Higher amount of spinel in fired samples led to improved microstructural and mechanical properties and thermal shock resistance.
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The Combustion of Organic Lightweighting Agents in the Chamotte Materials
Smékalová, Veronika ; Keršner, Štěpán (referee) ; Sokolář, Radomír (advisor)
Lightweight chamotte products are popular building material. There are many types of lightweight chamotte on the market, but the most popular lightening options are organic ingredients. This brings some problems to the production of these products. This thesis deals with the burning of various types of lighters from shards of fireclay materials. In the theoretical part are summarized raw materials, which are necessary for production of lightweight chamotte. The results of the published research studies on the topic of lightening of organic lightening products are being described here. The practical part deals with properties of products made of clay or kaolin with the addition of a certain amount of lighter. These added lighters are spruce sawdust, beech sawdust, peat, bran, paper slurry and anthracite. All these lighters are direct. For comparison, the cenospheres, which represent indirect lightweights, were also included in the research. For all specimens, the temperature interval of burnout of specimens, refractoriness, classification temperature, bulk density, thermal conductivity coefficient and other properties were defined.
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