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Effect of electron beam remeltin on binary mixtures deposited by the cold spray method
Novotný, David ; Řehořek, Lukáš (referee) ; Čupera, Jan (advisor)
This bachelor’s thesis deals with the effect of an electron beam remelting on binary mixtures of Fe-Al and Ni-Al, which were deposited by Cold spray. The Research study is focused on the basic principles of function and usage of the electron beam technology and the Cold spray method. Furthermore, binary systems of Fe-Al and Ni-Al are, along with their binary diagrams, also described in this part. In the Experimental part, the samples were remelted by an electron beam and consequently, the changes in microstucture were examined using electron and optical microscope.
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Microstructure stability of tungsten -ODS hetergeneous welds
Adam, Ondřej ; Sonnek, Pavel (referee) ; Jan, Vít (advisor)
The thesis is focused on microstructural stability of heterogeneous weld joint of ODS steel and tungsten. The theoretical part summarizes the basic information about the structure and properties of ODS steels and describes the methods of joining these steels with tungsten. In the experimental part, materials MA956 and WL10 were welded by using electron beam. The individual samples differ by preheating temperature or use filler material. After annealing at 800 °C/1h and 1000 °C/5h, a change of the weld metal microstructure was evaluated by using scanning electron microscope. The chemical composition was measured by energy dispersive spectroscopy. It has been found that during annealing, massive precipitation of particles occures in the whole volume of the weld metal. These particles were identified as Laves phase.
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Nickel silicides layer by electron beam melting of electro deposited layer
Petr, Jiří ; Pantělejev, Libor (referee) ; Jan, Vít (advisor)
This master’s thesis deals with the possibility of creating a compact nickel-silicide layer on austenitic substrates. The theoretical part describes a variety of surface treatments, silicide division, and basic principles of electron beam. The experimental part contains a description of used experimental methods for evaluation of samples, creation of Ni-Si coating using electroplating, and the parameters of electron beam used for melting the sample coating. The last part is devoted to structural evaluation of the sample coating and its microhardness.
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Modification of Elektron 21 magnesium alloy microstructure via electron beam treatment
Hanáček, Josef ; Šiška, Filip (referee) ; Čížek, Jan (advisor)
This work presents a basic research on the influence of electron beam technology modification on chemical, structural and phases changes of Elektron 21 magnesium alloy. The samples were systematically modified under various parameters of the electron beam and coatings on their respective surfaces were deposited via controlled plasma electrolytic oxidation (PEO) subsequently. The influence of the EB modification on the PEO coating formation was observed. Several samples with remelted fine-grained surface layer were obtained. Having a thickness of 10^1 to 10^3 µm, the average grain sizes in this layer were quantitatively evaluated. The performed EDS analysis revealed in identical chemical composition of the remelted surface layer and the original alloy material, despite the detected sample weight loss upon the EB treatment. XRD analysis revealed an increased content of Mg3(Nd,Gd) intermetallic phase in the remelted area. The PEO coatings were more compact and less porous as compared with their counterpart coatings on the original, unmodified alloy material.The results of the presented work showed, among others, a suitable microstructure and chemical composition of some of the modified samples that could potentially exhibit enhanced corrosion resistance as opposed to the unmodified material. The corrosion testing will be part of a follow-up study. More compact PEO coatings formed on some of the modified surface layers likely represent, too, a more durable variant as compared to the original material.
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Surface melting and possible alloying of cast iron with lamellar graphite by electron beam
Abu Khait, Yosef ; Kouřil, Miloslav (referee) ; Pacal, Bohumil (advisor)
In this thesis, the structural and mechanical changes, which took place in flake graphite cast iron after electron beam surface melting and chrome-nickel surface alloying, were studied. Furthermore, the effect of set parameters on properties and depth of the melted and alloyed region is also analyzed. In the experimental part, the analyzed microstructures, micro-hardness and the distribution of elements after melting and alloying, were presented. Structural differences of material regions caused by melting were described based on microstructures. In the end of diploma thesis, the conclusions of using EB technology for surface melting and alloying were discussed.
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Unconventional preparation technology of bulk material from Mg
Horálek, Matyáš ; Hasoňová, Michaela (referee) ; Březina, Matěj (advisor)
Topic of the bachelor's thesis is the procedure of preparation and processing of bulk magnesium powder by unconventional technologies. Bulk materials were evaluated from the point of porosity, microstructure and physically-mechanical properties in correlation with changes of parameters during preparation. Furthemore the influence of chosen processing parameters of electron beam was evaluated from structural properties and depth of the affected material. The outcome of this work is focused on study and optimalization of parameters during preparation and processing of bulk material.
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Surface melting of graphitic cast iron for hard layer preparation and its optimization
Adam, Ondřej ; Matlák, Jiří (referee) ; Jan, Vít (advisor)
The aim of bachelor thesis is description of microstructures, which were created by surface melting of ductile iron by using electron beam technology. The first part of bibliographic search deals with carbon and its effect on iron. The second part is focused on the general knowledge about cast irons, especially on graphitic cast irons. The last part of bibliographic search deals with electron beam technology. The practical part presents a microstructures, which were created by surface melting. Temperature cycles of the different material areas are described based on microstructures. In the end of bachelor thesis, there are chosen remelted layer with the best parametres and surface melting technology is optimized.
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Modification of HVOF and cold spray deposited coatings via electron beam technology
Vacek, Petr ; Šiška, Filip (referee) ; Čížek, Jan (advisor)
The aim of this thesis was to modify microstructure and coating-substrate interface of CoNiCrAlY coatings deposited by HVOF and cold spray on Inconel 718 substrates. Electron beam remelting and annealing in a protective atmosphere were used to modify the coatings. Microstructure, chemical and phase composition were analyzed. The effect of beam current, transversal velocity and beam defocus on remelted depth was evaluated. As-sprayed microstructure and chemical composition of coatings were analyzed and compared with remelted samples. The effect of annealing of the as-sprayed and remelted samples was evaluated. Remelted layers exhibited dendritic structure. Chemical composition changed only after remelting of interface and part of a substrate. When only the coating was remelted, chemical composition remained the same. Phases coarsened after the annealing. Chemical composition changed after annealing due to the diffusion.
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Surface treatment of selected steels using electron beam
Matlák, Jiří ; Jan, Vít (referee) ; Kouřil, Miloslav (advisor)
The aim of diploma thesis was preparation of hardened layer on three chosen types of materials with different alloying components content without surface melt by using electron beam technology. The influence of chosen process parameters was observed on the prepared hardened layers properties and shapes. In the first part of bibliographic search there are described electron beam properties, possibilities of his influencing and control. There is given example of complete set of electron beam are mentioned in the second part of theoretical research.
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