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Thermoplastic extrusion of ceramic materials with ionic and mixed conductivity
Kaštyl, Jaroslav ; Matoušek, Aleš (referee) ; Trunec, Martin (advisor)
In the bachelor thesis, an overview of the existing literature focused on thermoplastic extrusion method was worked out and based on the findings; the conditions for extrusion of mixtures with zirconia were optimized in order to produce rods. Great attention was paid to dimensional and shape precision of ceramic parts. Two methods were applied when preparing the ceramic mixtures – mixing and dissolving. These methods have been compared on the basis of the results achieved in rheological measurements of flow properties, microstructure and dimensional accuracy of the sintered rods. Having verified the efficiency of mixture dissolving, this method was used to prepare mixtures with different contents of cellulose and binder.
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Core-Shell Ceramic Structures Prepared by Thermoplastic Co-Extrusion Method
Kaštyl, Jaroslav ; Pabst, Willi (referee) ; Hadraba, Hynek (referee) ; Trunec, Martin (advisor)
In the doctoral thesis, the bi-layer ceramic bodies with core-shell geometry were prepared by thermoplastic co-extrusion method and for these composite bodies the mechanical properties were studied. For study of co-extrusion and mechanical properties were designed two composite systems. First system ZTA-A combined the dense core ZTA (zirconia-toughened alumina) and the dense shell Al2O3. Second system ZST-Z consisted of porous core and dense shell made from ZrO2 for both cases. In the thesis, the rheology of ceramic thermoplastic suspensions and their mutual influence during co-extrusion was studied. Subsequently, the debinding process and sintering were studied, and based on the optimization of all process steps were obtained defect-free bodies with core-shell geometry. The mechanical properties (elastic modulus, hardness and bending strength) were determined for sintered bodies. To estimate the stress path in the core shell bodies loaded in bending, the relationship considering different elastic moduli of the core and the shell was used. For bodies of ZTA-A system was increased the strength in comparison with monolithic bodies of the individual components. Thus, bodies with high surface hardness of shell from Al2O3 and moreover having high fracture strength in bending were obtained. The effective elastic modulus was decreased for bodies of ZST-Z system up to 25 % in comparison with the elastic modulus of dense monolithic samples. The same effective modulus of elasticity was possible to achieve with core-shell bodies while maintaining significantly higher fracture strength than monolithic porous bodies or pipes.
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Behaviour of the Interface of Low Toughness Materials
Halasová, Martina ; Pabst, Willi (referee) ; Tatarko, Peter (referee) ; Fintová, Stanislava (referee) ; Chlup, Zdeněk (advisor)
The work is focused on evaluation of factors influencing behaviour of interface in low toughness ceramic materials reinforced with fibres. The main aim was to characterise processing effects influencing the quality of fibre-matrix interface, with respect to final behaviour of composites at various loading type. The partial goal was to map the possibility of influencing the composite material by choice of matrix material, eventually by change of its processing, leading to change of interfacial properties without need of modification of reinforcement surface. The materials used in studied composites as a matrix were based on thermal transformation of polymer precursors, thus, the resulting materials were characterised in partially as well as in fully pyrolyzed state. Behaviour of interface in cpomposite materials was first evaluated from the global behaviour (i.e., change of mechanical properties) and in chosen representative composites also from the point of local changes in close surrounding of the interface (i.e., microstructure, chemical processes, fracture-mechanic processes, etc.) due to thermal exposition. In experiment were used particularly composite materials prepared by pyrolysis of polysiloxane resins reinforced by basalt fibres or Nextel™720 fibres. With respect to thermal resistance of the reinforcement, the basalt reinforced composites contained only partially pyrolyzed matrix (i.e., to temperature of 800°C), and in composites with Nextel™720 reinforcement was the matrix in form of fully pyrolyzed polymer into ceramic (SiOC). At partial pyrolysis of polysiloxane resin occurs rapid change of behaviour at temperature of 600°C. It was demonstrated, that around this temperature the formed interface with basalt fibre exhibits optimum adhesion/strength, allowing to reach sufficient level of composite strength at acceptable fracture toughness. Above temperature of 750°C occur significant difusion processes in the area of the interface and formation of new crystalline phases in the fibre, what deteriorates the fibre strength, and on the contrary, strengthen the interface cohesion, what leads to degradation of properties of the whole composite. At composite materials determined for high temperatures, reinforced by Nextel™720 fibres, was detected significant resistivity against oxidation caused especially by fully pyrolyzed matrix. As similarly important factor was observed the formation of mullite interphase in surface area of the fibre. Volume changes caused by formation of the interphase, difusional transport of the matter and thermal exposition led to formation of thermally and stress-induced micro-cracks, weakening interfacial surrounding in matrix as well as in fibre. This mechanism in contrast to amplifying chemical bond between fibre and matrix led to preserving of the composite properties also at high temperatures up to 1500°C. The work also dealed with effects of loading rate, where in contrast to static loading were observed different failure mechanisms. Realized research led to description and explanation of the influence of the fibre-matrix interface by change of matrix material processing parameters, which allow processing of economically advantageous and thermally stable composite.
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DPF for SI Engines
Pohludková, Lenka ; Prokop, Aleš (referee) ; Dundálek, Radim (advisor)
This bachelor thesis deals with gasoline particulate filters. Emissions of internal combustion engines and their impact on air pollution and human health, especially the impact of particulate matter, are discussed. It also describes what these filters are made of, where they are located in the car, and explains the principle of their function and regeneration.
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Familly house
John, Josef ; Janovský, Jaroslav (referee) ; Brukner, Bohuslav (advisor)
This work deals with the new family house for a four member family and detached design or architectural office in the town of Palkovice . Project documentation is processed in accordance with current applicable laws, regulations and standards. The building will be located on a separate building lot. The property is located close to III. class communication and all the necessary utilities. This is a two-storey building, on the first floor there are living room with kitchen, bedroom and sanitary facilities. There is also a shelter for car parking and a detached office with sanitary facilities . Ground-plan of the family house has the shape of two cantilevered perpendicular rectangles , whose outline dimensions are 18.75 x 9.00 m. The office building is shaped as a rectangle with dimensions of 8.75 x 5.75 m. The foundations are designed as monolithic from unreinforced concrete into the formwork foundation boards with embedded reinforcement. Vertical load-bearing structures are made of aerated concrete blocks. The vertical load-bearing structures of the shelter are made of galvanized steel elements and filling gabion walls. Ceilings are made of ceramic beam system with ceramic inserts HELUZ . Floors are made up of ceramic tiles and floating flooring. The building is covered with a flat roof single-shell thermal insulation. Above the shelter and the terrace there is a flat roof with a steel frame and wooden ceiling rafters. The ceiling is made up of ceiling boards Rheinzink. This work dealt with the preparatory and study work , executive documentation , text message, calculations of the thermal assessment , fire safety solutions and seminar work that addresses the problem of flat roofs.
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Preparation of nanocrystalline ceramic materials made from zirconia oxide
Vlček, Ondřej ; Prajzler, Vladimír (referee) ; Šťastný, Přemysl (advisor)
Bachelor thesis is focused on preparation of nanocrystalline stabilized zirconia ceramics. The theoretical part is dedicated to zirconia ceramics. Theoretical part describes and unveil the transformation-induced toughening mechanism in partially stabilized zirconia ceramics, the processing routes of these ceramic materials and their utilization. The research part describes preparation of yttria partially stabilized nanocrystalline zirconia ceramics by slip casting method.
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Pressure sensor made 3D structure
Hanus, Martin ; Pekárek, Jan (referee) ; Kosina, Petr (advisor)
This thesis deals with the points at issue of a 3D structure pressure sensor. The pressure sensor converts pressure into another physical quantity which is easier measure and which is processed subsequently. Usually ways of pressure sensing is for example capacitive, strain-gauge and optical. The 3D structures are constructed through the use of a LTCC technology, which can be laminated to create multi-layer structures, compared to standard high-temperature ceramics. Passive circuit components can be applied onto particular ceramic layers using either thin-layer or thick-layer technology. Practice part of thesis deals with several ways of construction a pressure sensor. First of all capacitive, strain-gauge and optical sensor and possible problems with construction individual sensors above all problems with lamination, cavity or burning
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Interconnection Technologies for 3D Electronic and Microelectronic Constructions
Nicák, Michal ; Pietriková,, Alena (referee) ; Starý, Jiří (referee) ; Šandera, Josef (advisor)
The doctoral thesis is focused on research on application possibilities of soldered interconnection structures especially for the use with innovative 3D structures assembled using the LTCC ceramic materials, PVD deposited and galvanically modified pads, solid core solder balls. It consists of several main parts. Introduction is followed by theoretical survey of current situation and technologies. Thesis continues with introduction of main goals and with summary of successively performed experiments and their results. End of the work belongs to summary of results and gained knowledge.
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The Effect of Raw Materials on Sound Insulation of Brick Body
Bosák, Filip ; Stančík,, Hynek (referee) ; Sokolář, Radomír (advisor)
Diploma thesis is concerned with opportunities of increase sound isolution index for bricks. In theoretical part is summary of present knowledge about acoustic properties ceramic body field and theoretical calculations and measuring sound insulation as well as. Practically part is divided on apply and basic research. Under apply research is experiment, that considers impact quantity of raw materials using at brick factory in the Holice on the most significant technological properties of plastic paste and brick body, additionaly with the considering chances of increase sound insulation index. In basic research is experiment, that evaluates impact common use domestic brick´s raw materials on sound insulation. Sound insulation is evaluated indirectly by transsmision rate of ultrasound in a both cases.
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