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Properties and in vitro Degradation of Metalic Biodegradable Materials
Ročňáková, Ivana ; Trojanová, Zuzanka (referee) ; Vojtěch,, Dalibor (referee) ; Podrábský, Tomáš (advisor)
Biodegradable metallic materials for medical applications have received considerable attention in recent years. The main reason is that they provide high potential for fabrication of temporal orthopedic implants such as bone fixation devices. Magnesium is an excellent candidate for fabrication of biodegradable implants due to its biocompatibility, mechanical properties similar to human bone and relevance for biological body functions. The fast degradation rate of magnesium and its biodegradable alloys in physiological environment limits its clinical application. Another attractive material in the field of biodegradable materials is zinc, which is among the essential elements in human body. Zinc exhibits an excellent corrosion resistance, and inferior biocompatibility compared to with magnesium. Hence, surface modification to form a hard, dense/porous, biocompatible and corrosion resistant modified layer has become an interesting topic in magnesium base biomaterials. Since hydroxyapatite is well tolerated by living organisms and in addition, improves the bone growth, it appears to be excellent candidate for such coatings on surface of biodegradable materials (e.g. Mg, Zn). This thesis is focused on comparison of corrosion behavior of pure non ferrous metals (Mg, Zn) and metals coated with hydroxyapatite, in simulated body fluids. The present approach is the use of modified atmospheric plasma spray technology to produce the hydroxyapatite coatings – suspension spraying. Composition and structure of the coatings and corrosion products were studied by light microscopy, scanning electron microscopy equipped with energy dispersive microanalyzer and X-ray diffraction. Corrosion of Mg and Zn samples was monitored by weight loss and determined by X ray and micro-tomography. The application of the HA coating resulted in decrease of corrosion rate of pure Mg. The corrosion rate of coated Mg samples was lower by 27,3 % in comparison with the corrosion rate of pure non coated Mg. Corrosion degradation of uncoated and coated Zn samples was minimal. The aplication of HA on the non ferrous surface appears to be a very promising method to improve corrosion and biological properties of these biodegradable materials.
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Corrosion of biodegradable magnesium alloys in Hank's solutions
Faltejsek, Petr ; Fintová, Stanislava (referee) ; Doležal, Pavel (advisor)
The aim of the thesis was to design a methodology for in-situ evaluation of degradation of selected magnesium alloys using AFM in SBF solutions. Study of the degradation of magnesium alloys in a chemically different corrosive environments of simulated body fluid (SBF - Hank's solution). For the pilot study were used magnesium alloys AZ31 and AZ61, manufactured by advanced method of squeeze casting. Part of the thesis was to evaluate the influence of the chemical composition and structure on the degradation properties of these alloys.
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Mechanical properties of magnesium alloy AZ91E prepared by ECAP method
Darida, Jiří ; Válka, Libor (referee) ; Pantělejev, Libor (advisor)
This thesis deals with mechanical and fatigue properties of magnesium alloy AZ91 processed by EX-ECAP method. This method involves the application of extrusion followed by equal-channel angular pressing. To obtain basic mechanical characteristics, the tensile test were carried out at room and elevated temperatures. Further the fatigue tests were performed and obtained data were used to compile S-N curve. The work also includes metallographics analysis of microstructure and fractographic analysis of fracture surfaces of tensile and fatigue test specimens.
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Bones implants based on Fe and Mg
Košíček, Adam ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This paper work deals with properties of metallic biomaterials in terms of their suitability for use as a temporary metal implants. The work focuses on biodegradable materials based on iron and suitable alloying elements, which would create a perfect implant. A part of this work describes procedure of creating biodegradable metallic samples with alloying element Magnesium and measuring the corrosion rates. There are a few theoretical chapters concerning permanent implants, function and composition of human bones, iron and magnesium in human body and biodegradable materials.
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Preparation and properties of bulk material from magnesium powder
Ruttkayová, Veronika ; Pacal, Bohumil (referee) ; Doležal, Pavel (advisor)
Diploma thesis focuses on preparation and characterization of bulk material prepared from pure magnesium powder. The topic includes all the parts of process of bulk material preparation, sintering at hot pressing, diffusion processes and structurally-mechanical properties with respect to final material porosity of the produced material. Thesis solving focuses on study and control of processes during bulk material preparation and description of the processes from physically-chemical point of view of the structure creation and final material properties.
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Preparation processes and characterization of bulk material from Mg and Zn powders
Hasoňová, Michaela ; Pacal, Bohumil (referee) ; Doležal, Pavel (advisor)
Topic of the diploma thesis is Mg-Zn bulk material preparation process by powder mixtures sintering at hot pressing. Structure, porosity and physically-mechanical properties of prepared bulk materials was evaluated. Obtained results and their interpretation were served as feedback for following optimization of individual processing parameters of bulk materials preparation. Thesis solving focuses on study and control of processes during bulk material preparation and description of the processes from physically-chemical point of view of the structure creation and final material properties.
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Fatigue endurance of extruded Mg alloy AZ91E
Sobola, Petr ; Štěpánek, Roman (referee) ; Pantělejev, Libor (advisor)
This thesis deals with fatigue behaviour of magnesium alloy AZ91E produced by extrusion. In the frame of this work, basic mechanical characteristics and data from performed fatigue tests were obtained. Further metallographic analysis of microstructure and fractographic analysis of broken specimens after fatigue tests were carried out.
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Technology of Galvanic Anodization of Non-ferrous Materials and Its Alloys
Remešová, Michaela ; Hadraba,, Hynek (referee) ; Čelko, Ladislav (advisor)
The thesis is focused on the theoretical description of the technology of anodizing of aluminium, magnesium, zinc and their alloys. In this work, methods for formation of oxide layers and the used chemical processes are described in detail. The experimental part of this work deals with formation of oxide layers on aluminium, magnesium and zinc of high purity under different conditions. Oxide layers of different thicknesses were created on all three experimental materials. Aluminium was anodized in a bath of 10% H2SO4, magnesium in the bath of 1 mol/dm3 NaOH, and zinc in the bath of 0.5 mol/dm3 NaOH. Processes were carried out at laboratory temperature. On the aluminium, continuous oxide layer was formed. Furthermore rule "312" was verified, that can indicatively be used for calculating the thickness of the resulting oxide layer on the aluminium. When using lower current of 0.08 and 0.2 A for magnesium anodizing, dark colored layer was created comparing to higher current of 0.5 A. More rough appearance of the oxide layer was produced with increasing voltage. Further, it was observed for magnesium that the resulting layer comprises of two sublayers. For zinc, black colored layer was created when the voltage 20 V and current from 0.4 to 0.5 A were used. In the layer, two sublayers were also observed. For lower voltage and current (0.05 A, 0.17 V), formation of the oxide layer on the zinc does not occur, but the crystallographic etching was observed.
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