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Preparation of Mg-Al-Ti bulk materials via powder metallurgy
Brescher, Roman ; Doskočil, Leoš (referee) ; Březina, Matěj (advisor)
This diploma thesis deals with research and preparation of bulk materials based on the Mg–Al–Ti system. The theoretical part summarizes the basic knowledge about magnesium alloys, focusing mainly on Mg–Al and Mg–Ti systems. Furthermore, basic information on powder metallurgy methods was included here, from the production of powder materials, through their compaction, to heat treatment and spark plasma sintering (SPS). The theoretical part ends with literature review on the current research of the Mg–Al–Ti system. In the experimental part, bulk materials based on the Mg–Al–Ti system was prepared using traditional methods of powder metallurgy, as well as using the SPS method. The microstructure of the material, elemental and phase composition was examined in this thesis. Subsequently, Vickers hardness and flexural strength were measured, and fractographic observation of the fracture surface was performed. It was found that the aluminum was completely dissolved during the heat treatment, but the titanium particles remained almost intact in the material and worked as a particulate reinforcement. Materials prepared by methods of conventional powder metallurgy showed increased porosity compared to materials prepared by the SPS, resulting in lower hardness and flexural strength. The hardness increased with increasing the amount of aluminum and titanium and with the amount of magnesium phase . Fractographic observation of the fracture surface suggests that a diffuse connection between the reinforcement and the matrix may have occurred after the sintering process.
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Multi-material 3D printing of titanium and aluminium alloys
Duchoň, Matěj ; Hutař, Pavel (referee) ; Koutný, Daniel (advisor)
Additive manufacturing of multi-material components is a promising way to produce parts that combine the properties of different materials. The thesis deals with the research, optimization of process parameters and methodology to produce multi-material parts using the SLM method. The aim is to create a mechanically durable interface between two materials based on titanium and aluminium. In order to determine the suitable combination of materials, a single track test was performed, which also established the initial process parameters and the effect of increased preheating temperature on the formation of defects at the material interface. This test provided the basis for the printing of bulk samples whose interfaces were analysed in detail using light microscopy, microhardness testing and EDS. Finally, the mechanical resistance of the interface was verified by tensile testing. According to the results of the single track test, titanium alloy Ti6Al4V in combination with aluminium alloy AlSi10Mg was selected. In further tests, it was found that if the preheating temperature is increased from 200 °C to 300 °C, the number of cracks at the interface is reduced by 31 %. The combination of increased preheating temperature and appropriate process parameters produced a crack-free material interface that exhibited high mechanical durability. The thesis provides a summary overview of the issues related to multi-material metal printing and the causes of individual defects that the interface of two different materials faces. The thesis may serve as a basis for further research on multi-material metal printing.
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Study of the influence of alloying elements on the solubility of titanium in magnesium
Staněk, Jan ; Buchtík, Martin (referee) ; Březina, Matěj (advisor)
This master’s thesis deals with the study of the influence of aluminium and zinc on the solubility of titanium in magnesium. The theoretical part summarizes the basic knowledge about magnesium and magnesium alloys with a focus on systems containing aluminium, zinc and titanium. It also describes powder metallurgy technology, specifically the preparation, compaction and sintering of metal powders. The theoretical part ends with literature review on the current research of ternary and quaternary magnesium alloys. The experimental part focuses on the preparation of magnesium materials alloyed with titanium, zinc and aluminium by powder metallurgy and the basic structural and mechanical characterisation of the prepared materials. The effect of alloying elements and temperature on the solubility of titanium particles in magnesium was investigated. It was found that the main condition for the dissolution of titanium in magnesium is the temperature of 800 °C and the presence of aluminium, which initiates the reaction by forming intermetallic compounds with titanium. After incorporation of titanium into the material structure, new intermetallic compounds were formed with all elements not previously described in the literature, in addition to the structures described.
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Forming of titanium alloys
Bednařík, Josef ; Podaný, Kamil (referee) ; Lidmila, Zdeněk (advisor)
The work was focused on the forming of titanium and its alloys in order to verify the ductile properties of titanium alloy VT 3-1. Using the upsetting test performed on the CZR 600 press and processed in the Dewesoft application, the strengthening curves for compaction at temperatures ranging from 25 °C to 800 °C were compiled. Based on the performed experiments, the titanium alloy VT 3-1 can be recommended for forming only at higher temperatures. It is recommended to select 700 °C as the lowest forging temperature limit. The material when being upset at lower temperatures showed poor formability due to the strengthening of the material. The yield strength during upsetting at room temperature was measured to be 1 100,8 MPa. In contrast, at 800 °C it has a value of 321,7 MPa. Hardness was determined before and after the test as an additional measurement. After the test, the measurement was performed on the front of the sample and in section. At 700 °C and 800 °C, the hardness resulted in dynamic recrystallization, which resulted in a decrease in hardness. The highest hardness was recorded in the middle of the sample at all temperatures. This result confirmed the thesis that there is a band of the most intense deformation in the perpendicular and axial direction of the sample.
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Growth of human osteoblasts SaOS2 on titanium modified with nanotubes.
Krýslová, Markéta ; Filová, Elena (advisor) ; Melkes, Barbora (referee)
This work summarizes information about the interactions between osteoblasts and nanostructured materials, which are of growing importance and are highly promising in regard to their application in medicine and in tissue engineering. The number of people with artificial replacements of tissues, such as bones, joints, teeth, cartilage, and tendons increases every year. Titanium and his alloys are extensively used for artificial tissue replacements. Titanium is favourable for its mechanical properties that allow the implant to remain in the place of implantation more than thirty years. For better osseointegration the surface of titanium can be modified with hydroxyapatite, coating with diamond-like carbon or plasma spray coating. Another option is to prepare a layer of nanotubes, which forms nanoroughness on material surface. The nanoroughness in turn improves physical and chemical properties of the material surface. Nanostructured materials mimic the natural bone tissue, support adsorption of specific proteins, improve the biocompatibility of the implants and positively influence cell behaviour, e.g. stimulate the synthesis and suitable conformation of specific molecules for cell adhesion and differentiation.
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Biomimetic modifications of titanium in bone tissue engineering.
Krýslová, Markéta ; Filová, Elena (advisor) ; Rampichová, Michala (referee)
When the big joints like a knee or hip joint are damaged, the solution of this problem is an artificial substitute. The replacement of damaged joints with endoprotesis helps to reduce the pain and to move normally. In the design of the implant is necessary to fulfil all requirements on the properties of the material. The surface of implant is important, because it is directly connected to bone tissue. After implantation, the negative effect include infection, inflammation or release of the implant due to limited osseointegration, may appear. The osseointegration can be improved by modifying the material surface. This thesis is focused on development and evaluation of advanced materials imitating the bone structure, especially nanoroughness and the presence of biomimetic component, such as hydroxyapatite. In this study is evaluated adhesion, proliferation, viability, differentiation, and synthesis of specific proteins of human osteoblasts like Saos-2 on titanium modified with nanotubes and plasma sprayed hydroxyapatite compared with smooth surfaces. Key words: titanium, nanotubes, osteoblasts, hydroxyapatite, nanoroughness
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Sol-gel synthesis of ternary ZnxTiyOz nanostructures for applications in solar cell technologies and photonics
Mrázek, Jan ; Nižňanský, Daniel (advisor) ; Pinkas, Jiří (referee) ; Pollert, Emil (referee)
The presented study deals with the sol-gel synthesis of nanocrystalline ternary phases of the general formula ZnxTiyOz, their characterization and potential application in photonics. Achieved results brings new fundamental knowledge about the processes leading to the formation of ZnxTiyOz nanocrystals from amorphous xerogels and gives novel information about structural and opto-electrical properties of prepared materials. Based on the presented results, most of all up-to-date reported ZnxTiyOz compounds with tailored nanocrystalline size and structure can be prepared as powders or thin films. Two sol-gel approaches based on the cluster process and direct heteronucleation were employed to prepare initial sol. Sols were optionally doped by Eu3+ ions to evaluate the effects of rare earth element to crystallization properties of formed compounds. In the first part of our study crystallization properties and structural evolution of thermally treated xerogels were analyzed. As a result a versatile method allowing the preparation of inverse spinel Zn2TiO4, cubic defect spinel ZnTiO3 and rhombohedral ZnTiO3 with tailored nanocrystal sizes was established. Initial composition and thermal annealing allow us to prepare selected ternary phase with tailored nanocrystal size ranging from tens of nanometers up to...
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Determination of Titanium and Phosphorus by Atomic Absorption Spectrometry
Jeníková, Eva ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
Předkládaná bakalářská práce se zabývá optimalizací metod stanovení titanu a fosforu technikou atomové absorpční spektrometrie s plamenovou atomizací ve složení acetylen-oxid dusný. Pro jednotlivá stanovení byly experimentálně nalezeny optimální hodnoty pro průtokovou rychlost acetylenu, koncentraci přídavku hliníku či vápníku, výšku paprsku nad hranou hořáku a jiné faktory pro zvýšení analytického signálu. Za těchto experimentálně zjištěných podmínek bylo provedeno stanovení a zjištění základní charakteristiky metod u obou prvků. Významnost stanovení těchto dvou prvků souvisí s tím, že materiály na bázi titanu a oxidu titaničitého povrchově modifikované sloučeninami fosforu jsou perspektivní pro řadu biomedicínských i průmyslových aplikací. Powered by TCPDF (www.tcpdf.org)
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Metastable beta titanium alloys for biomedical use
Preisler, Dalibor ; Stráský, Josef (advisor) ; Janeček, Miloš (referee)
In this work the effect of die-forging and annealing on the mechanical properties and microstructure of biocompatible metastable alloy Ti-35.3Nb-7.3Zr -5.7Ta-0.7O (wt. %) was studied. Light and scanning electron microscopy, microhardness tests and tensile tests were used to study all prepared conditions. As-cast and as-annealed conditions showed chemical inhomogeneities exhibited as dendritic structure, grains with size of hundreds of micrometers and numerous pores having size of units of micrometers. Precipitation of alpha phase particles was negligible in as-annelaed conditions and only grain boundary alpha paticles formed. Die-forged condition showed grain sizes in the wide range of hundreds of micrometers down to micrometers. Both as-annealed and die-forged conditions showed increased microhardness compared to as-cast condition, but there were no significant differences between different annealing conditions. Yield stress of 870 MPa was found for as-cast condition while as-forged condition exhibited even higher yield stress of 1120 MPa. In both conditions, good room-temperature ductility was demonstrated. Due to its high strength, this alloy is perspective for manufacturing of joint implants.
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Activation of ferrocene ligands by sandwich complexes of Group 4 metals
Kout, Matyáš ; Štěpnička, Petr (advisor) ; Vojtíšek, Pavel (referee)
This bachelor thesis deals with synthesis, reactivity and characterization of compounds resulting from the reactions of substituted ferrocene ligands with electron- deficient complexes of group 4 transition metals in oxidation state II with the aim of finding experimental conditions for preparation of complexes containing two metal atoms in one molecule. Reactions were performed under inert atmosphere and the products were crystallized. The obtained crystals were subjected to X-ray diffraction analysis and to NMR spectroscopy in order to elucidate molecular structure of the isolated products. Along the way, instability of the prepared compounds towards air oxygen and moisture has surfaced, though it also led to a discovery of several original compounds. Among these, the molecule containing peroxide ligand bonded to zirconocene fragment is worth noting as a fine example of oxygen molecule activation with low oxidative state complexes of transition metals.
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