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The developement of SLM laser strategy for lattice structure fabrication
Jaroš, Jan ; Dočekalová, Kateřina (referee) ; Vrána, Radek (advisor)
Additive technology (AT) is increasingly used to design unique parts, mainly due to the ability to produce complex structures such as lattice structures. However, this also includes the need to modify the process parameters or the production strategy of the AT, which is usually set to produce volume geometry. Using samples corresponding to the geometries of the lattice structures, the exact input values were measured, which were used to design the SLM (Selective laser melting) production process using a contour strategy. Thanks to this, vertical and angled (35.26°) struts with low porosity (up to 0.2 %), low surface roughness and high dimensional accuracy were produced. Porosity was measured on µCT, surface roughness and dimensional accuracy were measured on STL data. The results show that if the parameters of the SLM process are set correctly, it is possible to produce struts with low porosity and surface roughness using different combinations of laser power and scanning speed. The above findings were used in the creation of script that allow the selection of suitable process parameters to produce lattice structures.
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Current principles of Cold Spray coating, Cu coating characteristics
Barinka, Michal ; Jan, Vít (referee) ; Řehořek, Lukáš (advisor)
This bachelor thesis deals with the current principles of coating with the Cold Spray method. The research part deals with the principle of layer formation using the Cold Spray method. Furthermore, the current state of this technology on the market and its application in practice is summarized. The structure of deposited copper layer on two different substrates is evaluated in the experimental part.
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The origin of cracks in bulk aluminium alloys prepared by SLM technique
Tomeček, Michal ; Pantělejev, Libor (referee) ; Štěpánek, Roman (advisor)
This thesis aims to analyse the general character of manufacturing parts via the SLM (Selective Laser Melting) method, which belongs to the methodical group ALM (Additive Layer Manufacturing). In the first part the general technological process of SLM is described. In the second part the main focus is on the resulting influence of the procedural parameters and cons of using aluminium in SLM process. In the third and the last part the experiment is analysed. The main goal of this thesis is the research of influence of the procedural parameters on relative density and properties of aluminium alloys made by the SLM method and the analysis of the experiment that was carried out.
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3D Printing of Ceramic Bone Grafts with Different Internal Architecture
Novotná, Lenka ; Sekora, Jiří (referee) ; Provazník, Ivo (advisor)
Bioceramics in the form of scaffolds hold great promise in bone tissue regeneration. While the scaffold composition is important for biocompatibility, the internal architecture plays a key role in allowing proper cell penetration, nutrient diffusion, bone ingrowth, vascularization as well as mechanical properties. A solid freeform fabrication is a promising processing technique, allowing to study structural parameters independently. This bachelor thesis is focused on ceramic bone replacements with different internal structure. The thesis is divided into 8 chapters. The first four chapters briefly summarize the current state of the art in the following fields: bone structure, requirements for synthetic bone replacements, scaffold architecture, and fabrication methods with an emphasis on 3D printing. The next chapters deal with experimental part. The image analysis of mouse skeleton was performed. On the basis of the measured pore size (50 200 m) and according to the literature search, 16 structures with various shape, curvature and pore size were designed. The CAD models were printed by a stereolithography from a tricalcium phosphate dispersion. Sintered ceramic scaffolds exhibited an ideal structure for application in bone tissue engineering. Scaffolds contained both interconnected macro- and micropores of optimal sizes up to 500 m and about 3 m, respectively. The results confirm that stereolithography is suitable, and compared to others, precise method for preparing scaffolds having different internal structures. The individual structural characteristics influencing the scaffold behaviour will be possible to study independently to each other. And thus improve the scientific knowledge in the field of treatment of large segmental bone defects.
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Effect of cellulose ethers on properties of hydraulic lime
Skoupil, Jakub ; Rovnaníková, Pavla (referee) ; Vyšvařil, Martin (advisor)
This diploma thesis deals with the study of the influence of cellulose ethers on the properties of hydraulic lime mortars. The availability and price of cellulose ethers in the industrial market is very favorable, but we can´t meet with studies using cellulose ethers in building materials, where lime is used as a binder. Cellulose ethers are commonly used as thickening agents in cement-based materials. The purpose of this diploma thesis is to review if cellulose ethers are appropriate for use in hydraulic lime mortars, either as water retention agents that contribute by water retention to better hydration of hydraulic binder components or to affect the properties of mortar in the fresh state. The theoretical part is dedicated to cellulose ethers, especially their production and how they influence the properties of building materials. In the practical part, the thesis deals with the influence of the dose of five different types of cellulose ethers on the properties of hydraulic lime. The properties in the fresh state and the physical-mechanical properties of mortars were monitored over time.
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Development of method thermoporosimetry polymer powders
Urbánková, Radka ; Salajka,, Zdeněk (referee) ; Kratochvíla, Jan (advisor)
Thermoporosimetry is a technique to determine small pore sizes based on melting and crystallization point depression. The temperature shift was measured by Differential Scanning Calorimetry (DSC). Development of thermoporosimetry was carried out on silica with a well-characterized narrow pore size distribution. Several parameters were studied, which a have a direct influence on melting and crystallization point depression (for example: a quality of the solvent, filling the pores with the solvent, time and frequency of centrifuging, superfluous solvent removal conditions, etc.). The optimum conditions for the thermoporosimetry method were developed using high porosity silica. The optimized experimental conditions found for silica were applied to polypropylene powder with much lower porosity. Several polypropylene powders were synthesized using different polymerization catalysts and their porosity determined. Polymer powder morphology and structure was characterized by standard methods. Powder porosity obtained by thermoporometry, gas sorption, and BET methods was compared.
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Modification of porosity of bacterial cellulose in situ
Ondruchová, Barbora ; Pernicová, Iva (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deals with the production and modification of porosity of bacterial cellulose in situ using the bacterium Komagataeibacter xylinus. The theoretical part of the work was focused on the review of various methods of culturing Komagataeibacter xylinus and the production of porous samples of bacterial cellulose. The sizes of pores in bacterial cellulose depend mainly on the applied cultivation method. Bacterial cellulose produced statically or dynamically contains pores with the dimensions of approximately 0.02 µm to 10 µm. The difference in porosity in bacterial cellulose prepared by static and dynamic cultivation was confirmed experimentally. The production yields of bacterial cellulose were compared and discussed. Next, the porosity of the bacterial cellulose was modified in situ by the addition of wax particles. Scanning electron microscopy confirmed, that the accumulation of wax particles in the production medium could significantly support the porosity of bacterial cellulose and, at the same time, increase its production.
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Microstructure of AlSi9Cu3 alluminium alloy processed by SLM technology
Rychnovský, Daniel ; Nopová, Klára (referee) ; Vašáková, Kristýna (advisor)
This bachelor thesis deals with microstructure of aluminium alloy AlSi9Cu3 produce by SLM process. In theoretical part the SLM process is shown. In following topic, the defects which can occur during SLM are mentioned. In the end of the theoretical part the materials made by SLM and materials made by conventional method (casting) are compared. In experimental part the porosity of the samples made by SLM is examined by image analysis. The examine of the microstructure is also included. Results are discussed with literature.
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Cyclic plasticity and low-cycle fatigue resistance of materials prepared by the ColdSpray method
Brůža, Jaromír ; Šulák, Ivo (referee) ; Zapletal, Josef (advisor)
In the theoretical part, the diploma thesis focuses on Cold spray technology and parameters affecting the efficiency and quality of deposition. Next, there is an introduction to the fatigue process of materials. The theory is concluded with a summary of the current knowledge regarding materials created by Cold spray technology in the field of fatigue. In the practical part, volumetric bodies were created from the material EN AW7075. Specimens for tensile and fatigue tests were cut from the bodies by electrosparking. From the material and powder, metallographic cuttings were created for the determination of porosity using Archimedes’ principle, hardness according to Vickers and evaluation of EDS and EBSD analysis. The basic mechanical properties were determined from the tensile tests and the Wöhler-Basquin parameters were determined from the fatigue tests along with the life curve. Subsequently, a fractographic analysis of fracture surfaces using SEM took place.
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