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Mg-hydroxyapatite composite materials prepared by powder metallurgy
Řičánek, Adam ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
This bachelor thesis focuses on the preparation of magnesium-hydroxyapatite composite by powder metallurgy methods. The theoretical part of bachelor thesis deals with magnesium, magnesium alloys and magnesium materials. Furthermore, the theoretical part of the bachelor thesis deals with the basics of powder metallurgy, processing of materials prepared by powder metallurgy and metal matrix composites. In the experimental part of the bachelor thesis, two series of composites were made with different quantities of hydroxyapatite. Composites were made by mixing Mg with filler and by mixing and milling Mg with filler. Both series of composites were characterised by investigation of microstructure and element composition, hardness, compressive strength and corrosion resistance. Composites of mixed and milled series showed a highly homogenous structure. Hardness, compressive strength and corrosion resistance increased with increasing amounts of hydroxyapatite. Composites of mixed series showed heterogeneous structures. Hardness did not increase with increasing amount of hydroxyapatite. Corrosion resistance slightly increased with increasing amount of filler. Compression strength decreased with the increasing amount of filler due to lower cohesion and incompactness of the structure.
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Preparation of layered double hydroxides on Mg-hydroxyapatite-based substrates
Knoflíček, Milan ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The aim of this bachelor thesis was the preparation and characterization of coatings based on layered double hydroxides (LDH) on Mg composite substrates prepared by powder metalurgy. Hydroxyapatite (HAp) was used as a filler. The deposition of MgAl-LDH coatings on the surface of composites was carried out in a reaction mixture containing Al(NO3)3 at pH 10 and a temperature of 95 °C. The morphology and structure of the samples were characterized using scanning electron microscopy (SEM). The elemental composition of both composites themselves and the prepared coatings were characterized by energy dispersive spectroscopy (EDS). Analysis of the structure of Mg-HAp composites revealed that the frequency of HAp agglomerates increased with increasing reinforcement concentration. The highest frequency of agglomerates was detected in samples containing 20 and 50 wt. % HAp filler, where unlike the other samples, a significant deterioration of corrosion properties was also observed. In contrast, the best corrosion resistance was shown by the sample with 1 wt. % of filler. Other samples with filler contents from 0 to 10 wt. % were relatively similar in terms of corrosion resistance. Potentiodynamic tests demonstrated that coated samples exhibited significantly higher corrosion resistance compared to the uncoated samples. A uniform layer of LDH was observed in the coated samples with HAp content up to and including 10 wt. %. The presence of cracks related to the presence of bulky HAp agglomerates was detected on samples with higher reinforcement content, i.e. 20 and 50 wt. % HAp. Lower coating adhesion was also observed at these locations. It was found that to achieve high quality of LDH coatings, the optimum amount of HAp reinforcement of mixed and subsequently pressed Mg-HAp composites is up to 5 wt. % HAp. Higher HAp content in the samples generally led to the formation of defects and deterioration of corrosion properties.
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Optimization of biocompatible Ti/hydroxyapatite-based composite blends fabrication
Slovák, Tomáš ; Matějková, Michaela (referee) ; Čížek, Jan (advisor)
The bachelor's thesis deals with optimalization of biocompatible composite mixtures based on titanium and hydroxyapatite. The theoretical part is focused on biomaterials, specifying Ti and HA in more detail. The following section pertains to the principle of mechanical alloying. Preparation of the biocompatible composite mixtures by mechanical alloying and their following analyses are described in the experimental part. Results obtained in the experimental part are summarized in the discussion.
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Rheology of collagen hydrogels and its nanocomposites
Voldánová, Michaela ; Vojtová, Lucy (referee) ; Jančář, Josef (advisor)
This bachelor thesis deals with the phenomenological description of the rheological behavior of pure collagen I and its nanocomposites with addition of hydroxyapatite in four concentrations. Measurements were performed on a rheometer in the configuration cone – plate for a range of shear rates from 0 s-1 to 100 s-1 under defined conditions. At 4 °C, the collagen in samples of a specific composition remains dissolved; collagen retains his native character and the precursors of hydrogel are in the liquid state. By heating the aqueous solution of collagen with neutral pH leeds to spontaneous crosslinking process into fibrillar structure. At 37 °C, fibrils grow into the gel structure, however, the rate of its formation is dependent on the amount of collagen fibers. The measured data are processed in the form of flow and viscosity curves, from which the rheological behavior of the sample or structural and transformational changes in response to mechanical stress and temperature changes are evaluated and compared. This knowledge can be used to manipulate with hydrogels. Generally, it can help as a basis for further development of collagen, its interaction with HAP and factors influencing their stability or effectiveness.
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Structure and properties of Hydroxyapatite-Magnesium composites produced by the means of current assisted infiltration sintering
Casas Luna, Mariano ; Obrtlík,, Karel (referee) ; Georgarakis, Konstantinos (referee) ; Čelko, Ladislav (advisor)
Hořčík a kompozity fosforečnanu vápenatého jsou slibnými materiály pro biodegradabilní a nosné implantáty určené pro regeneraci kostí. Předložená práce je zaměřena na návrh, zpracování a charakterizaci vnitřně propojených kompozitů hořčíku s fosforečnanem vápenatým (Mg/CaP). Fosforečnany vápenaté jako jsou hydroxyapatit (HA), kalcium-deficitní hydroxyapatit (CDHA) a fosforečnan vápenatý (TCP) byly syntetizovány a použity pro výrobu skafoldů s kontrolovanou porozitou pomocí metody robocastingu. Byly připraveny porézní předlisky s ortogonální mřížkou a s vnitřními makropóry o velikosti ~500 µm, které byly následně slinovány za teploty 1100 °C po dobu 5 hodin. Vnitřně propojené Mg/CaP kompozity byly připraveny infiltrací čistého hořčíku a hořčíkových slitin obsahujících malá množství vápníku nebo zinku, například 0,2 hm.% vápníku a 1 hm.% zinku do porézních keramických skafoldů. Infiltrace byla provedena pomocí námi vyvinuté a nově popsané metody známé jako “Proudem asistovaná slinovací infiltrace” (z angl. Current Assisted Metal Infiltration (CAMI)). CAMI metoda umožňuje do 15 minut infiltrovat porézní keramický předlisek roztaveným kovem. Pulzujícím elektrickým proudem bylo dosaženo rychlého tavení a následného tuhnutí Mg/CaP kompozitů. Fyzikálně-chemické vlastnosti finálních vnitřně propojených kompozitů byly stanoveny pomocí rastrovací elektronové mikroskopie, počítačové mikro-tomografie, rentgenové difrakční analýzy a optické mikroskopie za účelem stanovení fázové distribuce a interakce mezi materiály. Kromě toho byla u připravených kompozitů hodnocena jejich mechanická pevnost v tlaku, degradační rychlost pomocí různých metod a biokompatibilita spolu s pokusem o uvedení těchto typů materiálů jako potenciálních degradabilních biomateriálů určených pro výrobu desek a/nebo šroubů pro ortopedické aplikace.
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Advanced ceramics for tissue engineering
Vojtíšek, Jan ; Koplík, Jan (referee) ; Bartoníčková, Eva (advisor)
This bachelor´s thesis deals issues of ceramics materials suitable for tissue engineering. An artificial substitute for human tissue can be divided to several generations. This include inert, bioactive and bioresobable materials. Resorbable substitutions are prepared from materials, which could substitute host tissue, for example hydroxyapatite. HA can be prepared in different ways (dry and wet way). To better application in medicine, ceramics foams prepared by in situ foaming or replication technique are using. Experimental part of this paper deals preparing of hydroxyapatite powder and process optimization. Samples was characterized by IR and Raman spectrometry, XRD analysis and particle size was studied by SEM. Ceramics foams was prepared by in situ foaming from Al2O3, HA and composites (in ratio 50 – 50, 75 – 25, 90 – 10). Porosity was evaluated by stereomicroscope, density and level of sintering was studied by SEM microscopy.
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Impact of macro channels on mechanical stability of bone scaffolds during indirect 3D printing
Vojníková, Michaela ; Novotná, Lenka (referee) ; Salamon, David (advisor)
Porous materials are currently subject to the great interest of tissue engineering. They provide unique properties such as bioactivity, biodegradability, osteoconductivity, and vascularization. Particularly, ceramic porous systems show appreciable potential in medical applications. However, there is a crucial problem with the porous scaffold on account of their bad mechanic properties and therefore they are presently used only at low-load locations. This thesis focuses on the preparation of the scaffolds made of hydroxyapatite by using the freeze-casting method where the indirect 3D printing was applied to get open channels with the size over 200 µm. It also compares the mechanical properties of the scaffolds with different internal structures and monitors how the implementation of different types of grids affects the resulting stability. The scaffolds were prepared with a different arrangement of macro-channel in the internal structure, but they had equal dimensions as common property. The 3D grid was implemented before freezing into the mold and afterward the grid was eliminated by sintering, leaving only a channel system with the size 540-600 µm in the final scaffold. The influence of the type of the 3D grid on the resulting mechanical stability of the scaffold was determined. Rotation of this grid does not have a significant effect on the result, while it only helps with cracking in the direction of the helix. The combination of these methods reports very good controllability with directed macro-channels in the resulting scaffold and therefore it is suitable for the preparation of the bone-implants with different structures.
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Study of preparation and properties of Ca-phosphates/ZrO2 biocomposites
Sláma, Martin ; Drdlík, Daniel (referee) ; Cihlář, Jaroslav (advisor)
The thesis was focused on preparation of bioceramic composite materials containing Ca-phosphates and zirconia fibers using electrophoretic deposition. A series of experiments were aimed at determining the appropriate composition of the suspensions. High-energy milling was used for preparing deposits with good physical and mechanical properties using EPD. The influence of milling time, the amount of monochloroacetic acid in isopropanol slurry indifferent electrolyte LiCl and ZrO2 were evaluated on the course deposition and the resulting properties of the deposits. Influence of sintering temperature, the milling time and the fiber content of ZrO2 on the chemical and structural composition was determined by X-ray analysis, measurement of density and structural analysis using a scanning electron microscope. Mechanical and bioactive properties of sintered deposits were determined depending on the milling time and content of ZrO2 fibers.
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Study of interaction of HA / biosklo based composites in simulated body fluid
Riša, Juraj ; Švec, Jiří (referee) ; Bartoníčková, Eva (advisor)
This work deals with bioceramic materials based of hydroxyapatite, bioglass and their composites. These materials are commonly used in medicine, especially as hard tissue substituents. They can be prepared by different types of syntheses, from which the most common were picked for this work – precipitation of hydroxyapatite and sol-gel method for bioglass. Thermal analysis and X-ray diffraction were used for characterization of prepared powders. This thesis studies mostly their features within the composite materials, which were foamed for better bone stimulation. Properties and possibility in bio application of materials is firstly studied through their interaction in simulated body fluids, which mimics ionic concentration of human plasma. Experimental part covers synthesis of ceramic powders, their characterization, preparation of mixtures and scaffolds foamed through in situ foaming, their sintering at ideal temperatures, characterization of porosity and phase changes due to sintering. Basic tests of apatite formation ability were provided by incubation of prepared scaffolds in simulated body fluid for 3, 7, 14 and 21 days and their assay in scanning electron microscopy. Changes in concentration of Ca2+ a PO4 3- ions as well as in weight of the specimen were tracked within the incubation period.
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Thermal spray coatings of bioceramics
Kašpárková, Kristýna ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
Bachelor´s thesis is focused on thermal spraying bioceramics. Bioceramic is designed to replace damaged parts of the human body. Practical use is mainly in orthopedics, jaw and facial surgery. This category of materials includes hydroxyapatite, which is characterized by biocompatibility and the ability to form a strong bond between the bone and the implant. The experimental part of the thesis was spraying 40 - pieces of dental implants for the company LASAK s.r.o. Plasma spraying technology was used to apply the hydroxyapatite coating. The required coating thickness was 60 m. The implant was sprayed and cleaned before spraying. Spraying was carried out in the laboratory of plasma coatings dental and skeletal implants ÚST FSI VUT Brno. A dimensional control was performed after plasma spraying.
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