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Nanocomposites with a metal matrix
Chlupová, Monika ; Kohout, Jan (referee) ; Zapletal, Josef (advisor)
This baechelor thesis is focused on metal matrix nanocomposites (MMNCs), whose research has started recently. In the first part of this thesis are generally defined composite materials, the larger part is dedicated to metal matrix composites (MMCs), on which are described the strengthening mechanisms that are also applied to MMNCs. The second part of the thesis is focused specifically on MMNCs. The concept of MMNCs and their distribution is defined first, followed by a definition of the reinforcement that can be used for the production of MMNCs. There are also described the posibilities for the production of these reinforcing phases, and their influence on the structural and mechanical properties of the final MMNCs. This section is followed by a description of possible processes of MMNCs production with their advantages and limitations. The last part outlines how research and development of these materials should be carried out in order to be commercially produced and used in the future.
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Optimization of fabrication technology and defect detection for ceramics structures
Chyťa, Filip ; Otáhal, Alexandr (referee) ; Skácel, Josef (advisor)
This work deals with the problems of defects in ceramics structures and packages, their detection and subsequent optimization of the manufacturing process in order to eliminate these defects. The first chapter summarizes ceramic materials in elec-trical engineering and deals specifically with Al2O3 and material GRANNALOX 9620 F and optimization of its production profile. The second chapter deals with preparation of the ceramic powder and its subsequent processing. The third chap-ter deals with detection of defects in the thus formed ceramic packages, testing their electrical, thermal and mechanical makings. In the next chapter I deal with my workflow, which I used in the production of packages, the way of production and testing of packages, including comparison of their makings.
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Development of photosensitive ceramic suspensions for 3D printing of porous bioscaffolds
Ravasová, Michaela ; Novotná, Lenka (referee) ; Částková, Klára (advisor)
The aim of the diploma thesis is the development of light-sensitive ceramic suspensions for the creation of porous bioscaffolds using 3D printing. The suspensions were based on aluminum oxide in the first phase and, in the second phase of the experimental part, on calcium phosphate. The theoretical part of the thesis focuses on describing human bone and the properties of bioscaffolds, providing an overview of biomaterials and methods for preparing porous bioceramics, along with a summary of previous results achieved by other scientific groups in the field. The experimental part describes the development of the suspensions. The influence of monomers, photoinitiators, dispersants, and ceramic powders on the properties of the suspensions and their photopolymerization ability was observed. By optimizing the suspensions, a suitable composition for 3D printing of scaffolds from aluminum oxide was achieved. The amount of dispersant and ceramic powder was determined based on rheological measurements, and the ratio of monomers and initiator content was adjusted according to gelation tests, where the dependence of resin polymerization on the illumination time was monitored. The suspensions were subsequently printed and sintered. The microstructure of the sintered bodies was characterized with a focus on defects specific to the debinding process. After creating a suspension suitable for 3D printing from aluminum oxide, the same procedure was applied to develop suspensions based on calcium phosphates. The outcome of the diploma thesis is a suspension based on aluminum oxide or tricalcium phosphate prepared from a mixture of di- and tetrafunctional acrylates in a weight ratio of 1:1, with 73-77 wt.% or 65 wt.% powder filling and 2 wt.% or 3 wt.% dispersant. The suspension is suitable for stereolithographic 3D printing of thin-walled bodies for biomedical applications.
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Effect Of Al2O3 Barrier On The Field Emission Properties Of Tungsten Single-Tip Field Emitters
Burda, Daniel ; Knápek, Alexandr
This research aims to obtain a more in-depth understanding of the field emission properties of tungsten single-tip field emitters (STFEs) coated with a several tens of nanometer thin barrier of Al2O3. The introduction of an additional barrier into the metal-vacuum interface system of the emitter can be beneficial to improve its performance. The tungsten emitters were prepared using a two-step electrochemical drop-off etching technique. Thin oxide barrier coatings were prepared by using low-temperature atomic layer deposition (ALD), a chemical vapor deposition technique. Field emission was studied in an internally developed field emission microscope (FEM) working in UHV vacuum (< 1·10−7 Pa), and the experimental field emission data were analyzed by the so-called Murphy-Good plotsThe value of the local work function of the grown oxide layer were investigated using Ultra-violet photoelectron spectroscopy (UPS).
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Optimization of fabrication technology and defect detection for ceramics structures
Chyťa, Filip ; Otáhal, Alexandr (referee) ; Skácel, Josef (advisor)
This work deals with the problems of defects in ceramics structures and packages, their detection and subsequent optimization of the manufacturing process in order to eliminate these defects. The first chapter summarizes ceramic materials in elec-trical engineering and deals specifically with Al2O3 and material GRANNALOX 9620 F and optimization of its production profile. The second chapter deals with preparation of the ceramic powder and its subsequent processing. The third chap-ter deals with detection of defects in the thus formed ceramic packages, testing their electrical, thermal and mechanical makings. In the next chapter I deal with my workflow, which I used in the production of packages, the way of production and testing of packages, including comparison of their makings.
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Nanocomposites with a metal matrix
Chlupová, Monika ; Kohout, Jan (referee) ; Zapletal, Josef (advisor)
This baechelor thesis is focused on metal matrix nanocomposites (MMNCs), whose research has started recently. In the first part of this thesis are generally defined composite materials, the larger part is dedicated to metal matrix composites (MMCs), on which are described the strengthening mechanisms that are also applied to MMNCs. The second part of the thesis is focused specifically on MMNCs. The concept of MMNCs and their distribution is defined first, followed by a definition of the reinforcement that can be used for the production of MMNCs. There are also described the posibilities for the production of these reinforcing phases, and their influence on the structural and mechanical properties of the final MMNCs. This section is followed by a description of possible processes of MMNCs production with their advantages and limitations. The last part outlines how research and development of these materials should be carried out in order to be commercially produced and used in the future.
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