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Manufacturing of calcium phosphates and silica based scaffolds for bioapllications
Virágová, Eliška ; Hadraba, Hynek (referee) ; Částková, Klára (advisor)
The aim of this diploma thesis was to prepare porous bioceramic scaffolds based on calcium phosphates and calcium phosphates doped with silica. Scaffolds are intended to be used in bone tissue engineering. Two main preparation methods were used for the creation of scaffolds – replica method and direct foaming method. Theoretical part of the diploma thesis is focused on a general description of the skeletal system, biomaterials and methods of preparation of highly porous calcium phosphate ceramics. Experimental part contains a description and the results of prepared scaffolds by above mentioned methods. The preparation process by the direct foaming method was optimized to obtain a defined structure. Calcium phosphate scaffolds containing 0–20 wt.% SiO2 were sintered and studied in terms of material characteristics (phase composition, pore size and porosity, microstructural study by scanning electron microscopy (SEM)), bioactive properties (simulated body fluid (SBF) interaction tests and tests of simulated degradation) and mechanical properties in order to evaluate the effect of silica doping. Scaffolds prepared by both methods were composed of a mixture of hydroxyapatite and/or tricalcium phosphate and cristobalite and wollastonite with comparable porosity in the range of 80–88 %. The pore size of the scaffolds prepared by the direct foaming method reached the interval of 5–250 µm opposite to template method reached the pore size up to 430 µm. The SBF interaction tests and tests of the simulated degradation confirmed the bioactive behavior of the prepared scaffolds and their ability to degrade under the simulated conditions. The scaffolds prepared by the direct foaming method showed better mechanical properties (compressive strength up to 1,8 MPa) than the scaffolds prepared by the template method. The results showed that the prepared scaffolds are suitable and promising for potential applications in bone tissue engineering.
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Electrospinning of bioglass and glass-ceramic fibers
Kozáková, Zdenka ; Šťastná, Eva (referee) ; Částková, Klára (advisor)
Bachelor thesis is focused on the preparation of fibers based on bioglass and glass ceramics. The theoretical part of the work summarizes the division and description of biomaterials and their use in biomedical applications. The main part of the work deals with the preparation of bioglass with a focus on the preparation by electrospinning. Experimental part is focused on the preparation of fibers based on bioglass by electrospinning. Different types of bioglass precursors were studied and their spinnability, morphology and bioactivity of the prepared fibers were assessed. The fibers were analyzed by scanning electron microscopy and interactions in simulated body fluid. Fibers prepared from bioglass 45S5 and polyvinylalcohol precursor were evaluated as promising for biomedical applications.
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Synthesis of functional ceramic powder materials
Čípová, Eva ; Maca, Karel (referee) ; Částková, Klára (advisor)
The theme of the work is electroceramic materials, particularly materials based on perovskites. The theoretical part describes electroceramic materials, their applications and possibilities of their synthesis. The experimental part focuses on the synthesis methods in liquid media and solid phase of barium strontium titanate. The prepared powders were characterized by morphology, phase composition and particle sinterability. It was found that weakly agglomerated particles with a single phase composition, perspective for the preparation of dense bulk ceramics, were prepared by the metod in liquid phase, especially by precipitation.
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Antibacterial properties of bioceramic materials
Achberger, Šimon ; Částková, Klára (referee) ; Salamon, David (advisor)
Implant surgery carries a risk of infection caused by bacterial contamination of the implant surface. An effective way to inhibit proliferation of bacteria is via antibacterial surfaces, however, their usage is medically and technologically difficult. Previous research shows that cicada wing topography exhibits unique bactericidal properties. In this thesis, various topographies were fabricated using heat treatment under hydrothermal conditions. The goal was to produce a surface covered by high aspect ratio structures with 60–215 nm width and 200–300 nm length. A relative density of 85%, 12 hrs long heat treatment and solution pH 4 and 5,6 had a positive effect on formation of thin surface structures. Quantity of morphological changes was proportional to -tricalcium phosphate content.
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Machining of ceramic bodies using CAD-CAM
Kaplan, Lukáš ; Částková, Klára (referee) ; Kaštyl, Jaroslav (advisor)
The literature part of bachelor's thesis deals with ceramic materials based on Al2O3 and ZrO2, methods of sample preparation for consequent machining, different methods of machining, especially the technology of CNC machining in non-sintered and sintered state with their comparison. The thesis presents possible examples of the use of ceramic parts. The experimental part of the thesis deals with the machining of ceramic based on ZrO2 using different types of ceramic powders, methods of preparation and the choice of the sintered temperature in relation to its properties. The best results were achieved with SZ-3Y ceramic material sintered at 1550 °C for 2 hours, strength values were 1203 MPa, roughness of surface Ra was 126 nm a grain size was 382 nm.
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Synthesis and fabrication of lead-free piezoceramics
Řeháková, Bára ; Pouchlý, Václav (referee) ; Částková, Klára (advisor)
The topic of this thesis is synthesis and preparation of lead-free pizoceramic with perovskite structure, in particular potassium-sodium niobate (KNN). In theoretical part are described possibilities of KNN synthesis and of it’s shaping and sintering. Experimental part deals with three types of synthesis described in the theretical part – solid state reaction, hydrothermal synthesis, sol-gel synthesis, and subconsequentional shaping of prepared powders by uniaxial pressing, cold isostatic pressure method, sintering (classical in oven, in some cases SPS – spark plasma sintering) of such green body and their following properties like relative density, grain size or charge constant. Preparation of KNN powder by each described method took place, followed by shaping and sintering. Best properties were shown by SPS sintered samples, which reached the highest density and lowest grain growth.
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Fabrication of ceramic materials for piezoelectric applications
Karkuszová, Karina ; Spusta, Tomáš (referee) ; Částková, Klára (advisor)
The content of this thesis is about preparation and processing of lead-free piezoceramic materials with perovskite structure. Potassium sodium niobate (KNN) powder was prepared by solid state reaction (SSR) and liquid phase reaction (sol-gel reaction). The powders were formed by uniaxial and isostatic pressing and further sintered. The density, grain size and morphology were determined on the sintered samples. The powder, synthesised by SSR and sintered in a conventional furnace, was chosen as a standard. The maximum density achieved on samples after optimization of sintering cycle was 93 %TD. The sintering optimization involved a homogenization step at 950 °C, which promotes the correct development of the phase composition and microstructure, followed by sintering at 1120 °C. The same approach and sintering cycle were used for sintering the samples, prepared by sol-gel synthesis. The maximum density of the samples prepared by sol-gel reaction and sintered in a conventional way, was 92 %TD. For further comparison, both of the synthesised powders were sintered using SPS (spark plasma sintering), which increased their final density up to 97 %TD. The approximate value of the piezoelectric coefficient d33 (pC/N) has been measured on selected SSR samples with pure phase composition ((K0,5Na0,5)NbO3). The best measured value of d33 was around 100 pC/N.
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Synthesis of ceramic powder materials in the presence of the ultrasound field
Kočicová, Pavla ; Bartoníčková, Eva (referee) ; Částková, Klára (advisor)
The thesis concerns the synthesis Ceric Oxide, Samarium Oxide and Samarium doped Cerium Oxide. The theoretical part is focused on the characteristics, applications and possibilities of the Cerium Oxide synthesis. The experimental part describes the precipitation of the Cerium Oxide powder. The synthesis of the powders were proceeded in the normal conditions or in the presence of ultrasonic field. For the purposes of description of the ready powders the x-ray diffraction (XRD) and the raster electron microscopy (SEM) were used. The ceramics were made of the selected powders where the structure was described by SEM, the density by Archimedes´Method and the grain size by grid-line intersect method. Using the precipitation synthesis, the pure powders of Ceric Oxide, Samarium Oxide and Samarium doped Cerium Oxide were prepared. The powder morphology was strongly involved by the pH level and by ageing time. The ultrasound was accelerating the ageing. At the values of pH > 11 the rodlike particles were created. The ageing time and the ultrasound supported the creation of the rodlike particles. The ceramics made of the powder with the presence of the rodlike morphology showed the density up to 97,14% of the theoretical density.
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Synthesis and Study of Nano-Structured Perovskites for Applications in Organic Electronics
Jančík Procházková, Anna ; Kuřitka, Ivo (referee) ; Částková, Klára (referee) ; Krajčovič, Jozef (advisor)
Nanočástice perovskitů halogenidů kovů vykazují unikátní vlastnosti, především výjimečně vysoké hodnoty kvantových výtěžků fluorescence, které předurčují tyto materiály pro aplikace v optoelektronických a fotonických zařízeních. Tato práce popisuje přípravu nanočástic perovskitů halogenidů kovů pomocí stabilizačních činidel inspirovaných přírodou. Stabilizační činidla zde slouží nejen ke stabilizaci, ale i k modifikaci povrchu nanočástic za účelem zvýšení funkčnosti výsledných nanostruktur. Úvod práce popisuje optimalizaci přípravy nanočástic precipitační technikou za použití stabilizačních činidel; jako stabilizační činidlo byl zvolen adamantan-1-amin spolu s hexanovou kyselinou. Bylo prokázáno, že klíčový vliv na optické vlastnosti výsledných koloidních roztoků má volba rozpouštědel a teploty při precipitaci. Mimo jiné byl zkoumán vliv koncentrace prekurzorů na výslednou morfologii a optické vlastnosti nanočástic a jejich koloidních roztoků. V neposlední řadě byly nanočástice stabilizovány adamantan-1-aminem spolu s různými karboxylovými kyselinami a byly studovány optické vlastnosti a koloidní stabilita výsledných koloidních roztoků. V dalším kroku byly nanočástice perovskitů stabilizovány pomocí proetogenních aminokyselin L-lysinu and L-argininu. Takto stabilizované nanočástice vykazovaly úzká emisní spektra ve viditelné oblasti a kvantové výtěžky fluorescence dosahující hodnot téměř 100 %. Stabilizace nanočástic prostřednictvím postranních skupin aminokyselin byla prokázána navázáním chránící terc-butoxykarbonylové skupiny na -amino skupinu. Nanočástice stabilizované modifikovaným lysinem v průběhu jejich přípravy vykazovaly závislost optických vlastností na přítomnosti vody. Předpokládá se, že molekuly vody jsou schopné kontrolovat růst krystalové mřížky po navázání na prekurzory perovskitů a ovlivňovat tak výslednou velikost nanočástic, což vede k projevení kvantových jevů. Spojení nanočástic perovskitů s peptidy představuje nový typ materiálů kombinujících výjimečné optické vlastnosti se samoorganizačními a senzorickými vlastnostmi. Tento koncept byl představen přípravou nanočástic perovskitů stabilizovaných cyklo(RGDFK) pentapeptidem. Vzhledem k citlivosti peptidů na jejich byly nanočástice stabilizovány peptidovými nukleovými kyselinami, robustními analogy nukleových kyselin. Ke stabilizaci nanočástic byl připraven monomer a trimer peptidové nukleové kyseliny obsahující thymin jako dusíkatou bázi. Thymin byl na povrchu nanočástic dostupný k interakci s adeninem přes vodíkové můstky umožňující přenos náboje. Kombinace peptidových nukleových kyselin a perovskitů s unikátními optickými vlastnostmi otevírá aplikační možnosti zejména v oblasti optických senzorů.
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Electrospinning of ceramic fibers
Nemčovský, Jakub ; Kaštyl, Jaroslav (referee) ; Částková, Klára (advisor)
This diploma thesis focuses on the fabrication of ceramic fibres by electrospinning. The theoretical part of the thesis summarizes the currently available information regarding ceramic fibres, their properties, applications and fabrication. The theoretical part also describes the process of electrospinning as one of the most frequently used methods of nanofibre fabrication, as well as the parametres influencing this process. The experimental part is aimed at the fabrication of ceramic fibres based on titania, pure non-doped zirconia and yttria-doped zirconia by electrospinning and at the characterization of thus fabricated fibres. Ceramic precursors based on propoxide and polyvinylpyrrolidone were subjected to electrospinning. The experimental part of this diploma thesis also describes the influence of precursor composition, process conditions and calcination temperature on the morphology and phase composition of the fibres. Precursors were characterized by viscosity measurements. Thermogravimetric analysis (TGA), Röntgen analysis (RTG) and scanning electron microscopy (SEM) were used to describe the fibres. By performing electrospinning of precursors based on titanium propoxide and subsequent calcination at 500-1300 °C, TiO2 fibres with thickness of 100-2500 nm were fabricated. The phase composition changed with calcination temperature from 500 °C from anatase phase through rutile blend to pure rutile at 900 °C. By performing electrospinning of precursors based on zirconium propoxide and subsequent calcination at 550-1100 °C, 0 – 8 mol% Y2O3 doped ZrO2 fibres with thickness of 50-1000 nm were fabricated. An analysis of fibres based on non-doped ZrO2, calcined at 550 °C showed a composition of predominantly monoclinic phase. An analysis of 3 or 8 mol% Y2O3 doped ZrO2 fibres calcined at 900 °C showed a composition of predominantly tetragonal phase or purely cubic phase, respectively. With the increasing calcination temperature, the morphology of the fibres changed from porous nanostructure to chain-like non-porous structure consisting of micrometer grains of TiO2 or ZrO2. The ZrO2 fibres calcined at 700 °C remained flexible as well as the spun ones, while their fragility increased with the increase in calcination temperature.
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