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Design of powder preheating for cold spray technology
Kalina, Jan ; Čupera, Jan (referee) ; Řehořek, Lukáš (advisor)
Cold spray is a technology that ranks among the thermal coatings. Its main idea is to prevent both the sprayed and the underlying material from reaching the melting temperature in order to reduce the level of surface oxidation. Cold spray is a relatively young technology that is still being researched. The effect of preheating the sprayed material on the material characteristics of the cold spray is one of the research questions. As part of this work, a device for preheating the powder to temperatures of up to 650 °C is designed in such a way as to minimize interference with the current construction of the Cold Spray workstation at the ÚMVI FSI BUT in Brno. The design is based on significant simplifications of the thermal model of the preheating device and heat losses. In the theoretical part, the reader was introduced to the history of Cold Spray, the effects of various technological parameters of Cold Spray on the resulting spray. Furthermore, the requirements for the preheater device were discussed, several variants of the device design were proposed, and the equations used for the device design were written. In the practical part, the required data for the design of the equipment is obtained for the required materials of the sprayed material, different temperatures, and other input parameters of the Cold Spray injection with the help of equations from the theoretical part. Based on them, the final design of the preheater device is compiled.
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Powder feeder design for multi-material metal 3D printing
Kulda, Martin ; Malý, Martin (referee) ; Grygar, Filip (advisor)
This bachelor thesis deals with the issue of multi-material metal 3D printing, specifically the method of material transfer between containers and powder application on the work surface. The aim of this bachelor thesis is to design, implement and test a dispensing device for refilling the coating head for multi-material metal 3D printing and to optimize the design of the coating head itself. Based on the research, conceptual designs were developed and subjected to a series of tests. The results of these tests led to the development of a specific design solution, including both the coating head and the dispensing device. These solutions were subsequently implemented and tested for key functions. The implemented solution enables reliable material transfer between containers as well as to the work surface. It also allows easy and quick exchange of the magazines themselves in case of printing a different set of materials.
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3D printing with silver and its use in jewellery
Thomas, Marek ; Langerová, Petra (referee) ; Sučková, Magda (advisor)
Hlavním cílem této práce je najít vhodný typ aditivní tiskárny, která by byla schopna kvalitního 3D tisku stříbrných šperků. Práce seznámí čtenáře s několika typy aditivních tiskáren (FDM, SLA, DMLS a dalších), jejich využitím v praxi a fyzikálním a chemickým chováním stříbra při aditivním tisku. Důraz bude kladen na praktické uplatnění těchto speciálních 3D tiskáren, a to především ve šperkařství. Poslední část práce se pokusí zodpovědět otázku, zda je technicky a ekonomicky proveditelné sestavit a bezpečně provozovat danou 3D tiskárnu v menších firmách či v domácím prostředí.
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Design of powder preheating for cold spray technology
Kalina, Jan ; Čupera, Jan (referee) ; Řehořek, Lukáš (advisor)
Cold spray is a technology that ranks among the thermal coatings. Its main idea is to prevent both the sprayed and the underlying material from reaching the melting temperature in order to reduce the level of surface oxidation. Cold spray is a relatively young technology that is still being researched. The effect of preheating the sprayed material on the material characteristics of the cold spray is one of the research questions. As part of this work, a device for preheating the powder to temperatures of up to 650 °C is designed in such a way as to minimize interference with the current construction of the Cold Spray workstation at the ÚMVI FSI BUT in Brno. The design is based on significant simplifications of the thermal model of the preheating device and heat losses. In the theoretical part, the reader was introduced to the history of Cold Spray, the effects of various technological parameters of Cold Spray on the resulting spray. Furthermore, the requirements for the preheater device were discussed, several variants of the device design were proposed, and the equations used for the device design were written. In the practical part, the required data for the design of the equipment is obtained for the required materials of the sprayed material, different temperatures, and other input parameters of the Cold Spray injection with the help of equations from the theoretical part. Based on them, the final design of the preheater device is compiled.
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Inverse-Heusler Mn2FeSi alloy prepared by powder metallurgy route
Životský, O. ; Skotnicová, K. ; Čegan, T. ; Juřica, J. ; Gembalová, L. ; Zažímal, František ; Jirásková, Yvonna ; Szurman, I.
The Mn2FeSi inverse-Heusler alloy was prepared by solid-state reactions using ball milling for 168 h in n hexane. Two milling procedures varying in the ball-to-powder ratio, namely 4:1 and 10:1, were used to follow \ntheir influence on alloy formation and its physical properties. In both cases no Heusler structure was obtained \ndirectly and therefore the subsequent annealing at 1223 K for 1.5 h in pure Ar was applied. The energy dispersive X-ray analysis resulted in the chemical composition about 49.0-49.9 at% Mn, 25.3-25.6 at% Fe, and \n24.8-25.4 at% Si, in a good agreement with nominal one. X-ray diffraction of both powders confirmed inverse Heusler XA structure of lattice parameters 0.5675 nm (4:1) and 0.5677 nm (10:1), only slightly higher as \ntheoretically obtained 0.560 nm. The presence of minor oxidation phases was also observed in the particle \nstructure of powders. Magnetic properties were analysed at low and room temperatures. Both alloys exhibit \nparamagnetic behaviour at room temperature confirmed by transmission Mössbauer spectroscopy \nmeasurements. Different magnetic behaviour of alloys is observed below 65 K.
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Development of a strategy for 3D printing of copper using Laser Powder Bed Fusion
Kryšpín, Vojtěch ; Vaverka, Ondřej (referee) ; Malý, Martin (advisor)
Copper sees vast usage in aeronautical, electrotechnical and energy industries due to its excellent machinability and thermal and electrical conductivity. In combination with modern computational approaches such as topological optimalization, additive manufacturing of copper has a great potential. My work has focused on creating a sample with the highest relative density through the application of recoating and remelting strategies. The best specimens which reached relative density over 99,1% were created with the following printing parameters: LP = 400 W, LV = 400 m·s-1 a HD = 0,01 mm.
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Trendy ve využití hmyzí suroviny v potravinách
Polák, Daniel
This bachelor thesis deals with the use of edible insects material in the food industry. Around 2000 edible insect species have been recorded worldwide and are commonly consumed in Africa, Asia and Oceania. In recent years, edible insects have also become a major topic of discussion in the Western world. In the European Union, legislative steps have been taken to categorise certain species of the edible insects as food. On the European market, products made from the yellow mealworm, the house cricket, the migratory locust and the lesser mealworm can be found. These edible insects are a rich source of protein, fat, vitamins and minerals. It also contains the fibre chitin which is associated with lower digestibility of insect products and may also act as an allergen. Some nutritional substances may be subject to the development of innovative technologies. For example, proteins from the migratory anemone have the potential for the development of edible packaging or chitin fibre may be another alternative source to obtain chitosan.
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Development of a strategy for 3D printing of copper using Laser Powder Bed Fusion
Kryšpín, Vojtěch ; Vaverka, Ondřej (referee) ; Malý, Martin (advisor)
Copper sees vast usage in aeronautical, electrotechnical and energy industries due to its excellent machinability and thermal and electrical conductivity. In combination with modern computational approaches such as topological optimalization, additive manufacturing of copper has a great potential. My work has focused on creating a sample with the highest relative density through the application of recoating and remelting strategies. The best specimens which reached relative density over 99,1% were created with the following printing parameters: LP = 400 W, LV = 400 m·s-1 a HD = 0,01 mm.
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Fractal aspects of flow and consolidation behaviour of microcrystalline cellulose.
Šofranková, Alexandra ; Šklubalová, Zdeňka (advisor) ; Svačinová, Petra (referee)
7 2 Abstract Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of: Pharmaceutical Technology Consultant: doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Alexandra Šofranková Title of Thesis: Fractal aspects of flow and consolidation behaviour of microcrystalline cellulose The object of this diploma thesis was to study the flow and consolidation characteristics of three types of microcrystalline cellulose. The granulometric characteristics, including the linear fractal dimension, were estimated using the optical microscopy. The bulk and tapped density, the angle of repose and the flow rate through an orifice of the hopper were evaluated. True density of the materials and the porosity of a loose powder bed were determined by helium pyknometry. The changes of density by the gravity consolidation were studied; the relationship of Hausner ratio on the number of taps describes best the differences in the consolidation behaviour of the substances. Modelling the consolidation kinetic by the exponential law allowed to determine the parameter N1/2, which shows the number of taps needed to reach one half of the powder volume reduction. The values of N1/2 within a range of 6,9-18 correlated well with the particle size of the used types of microcrystalline cellulose.
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Homogenization of powder blends using a Turbula mixer.
Litošová, Martina ; Šklubalová, Zdeňka (advisor) ; Mužíková, Jitka (referee)
1 Abstract Charles University, Faculty of Pharmacy in Hradci Králové Department of: Department of Pharmaceutical Technology Supervisor: Doc. PharmDr. Zdeňka Šklubalová, Ph. D. Consultant PharmDr. Karel Palát, CSc., Mgr. Žofie Trpělková Student: Martina Litošová Title of Thesis: Homogenization of powder blends using a Turbula mixer. In this experimental work, the influencing of the homogeneity of the powder mixture of acetylsalicylic acid (ASA) and microcrystalline cellulose (Avicel PH102) due to the rotational speed of the mixing container in a range of 23−101 rpm, and the mixing time was studied using the Turbula shaker mixer. Within time interval 2-62 minutes, the content of ASA in samples was measured by near-infrared spectrometry. The expression of standard deviation was used to evaluate the homogeneity of samples. The best results were detected at a rotational speed of 34 rpm within time interval of 14−30 min.
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