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Surface treatment of selected steels using electron beam
Oríšek, Petr ; Jan, Vít (referee) ; Kouřil, Miloslav (advisor)
The thesis aims for the surface treatment of materials using electron beam. It includes a literary research describing physical principle and properties of the electron beam. This research also presents possible influencing of the beam and describes the construction of the device that generates the beam. Various applications of the electron beam for the material treatment are presented in the second part of the paper. Within this thesis an experiment with the heat treatment of the steel surface by the electron beam has been realized. The experiment was aimed at creating a layer as deep as possible without melting the surface. The results and their evaluation are presented in the experimental part of the thesis. The attention is also paid to selected process parameters.
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Electron beam welding of ODS materials
Jankůj, Luděk ; Čížek, Jan (referee) ; Jan, Vít (advisor)
Thesis on Electron beam welding of ODS materials is divided into theoretical and experimental part. In the first part the theoretical research work focuses on the accurate description of the candidate materials in a research fusion reactor ITER. Following are detailed constructional ODS materials and tungsten alloy as a material of the first wall. The second part of the theoretical research deals with various possibilities of joining high-melting dissimilar materials such as brazing or electron beam welding as well, which will be established in the experimental section. The experimental part of the thesis deals with a joining ODS steel MA 956 with sintered carbide WC-Co and ODS tungsten. These materials are welded by electron beam. Individual samples are distinguished used filler material, preheating or welding parameters. This thesis contains photographic documentations of microstructure the welding samples, results from scanning electron microscopy, and measurements of microhardness across the weld metal.
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Electron beam welding of Ti 6Al 4V
Skalka, Jan ; Dupák, Libor (referee) ; Mrňa, Libor (advisor)
The thesis is dedicated to welding combination of titanium alloy Ti-6Al-4V and austenitic steels 1.4301 by electron beam. Based on literature studies of bonding titanium and its alloys with steels, it was proposed to select for welding interlayer of copper, which could limit the impact of intermetallic phases on the mechanical properties of the weld seam and enable the creation of weld. For welding the pipe samples were used three methods of welding with various welding parameters. Samples which remain after thermal cycling vacuum-tight, were then further analyzed (micro-hardness, tensile test, etc.).
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Electron Beam Micromachining of Nonmetalic Materials
Dupák, Libor ; Mrňa, Libor (referee) ; Bábor, Petr (referee) ; Lencová, Bohumila (advisor)
The thesis deals with electron beam micromachining of nonmetallic materials like glass, ceramics and plastics. A brief description of the device on which the experiments were carried out is included; the author has participated on its development. Main topic is experimental study of influence of main electron beam parameters on results of machining. Examined parameters include accelerating voltage, beam current, focusing and speed of machining. Influence of beam deflection is analyzed. Method of sequential machining by repeated passes of the electron beam is presented. Main examined materials are quartz glass, alumina and selected plastics. The usefulness of the technology is shown by several practical applications.
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Electron Beam Control and Diagnostics for Advanced Technologies
Zobač, Martin ; Kolařík, Vladimír (referee) ; Průša, Stanislav (referee) ; Lencová, Bohumila (advisor)
The thesis deals with problems of control and diagnostics of electron beam technological devices which use electron beam for localised intensive heating of a material. A brief description of the electron beam welder MEBW-60/2 is included; the author has participated on its development and implementation. Main topics are the analysis of deflection system properties and the measurement of current distribution of the beam (so-called beam profiles). Geometrical aberrations, hysteresis, stability and dynamics of a single-stage magnetic x-y deflection system are described. Suitable measurement procedures and correction methods are introduced. Methods of transverse and longitudinal beam profile acquisition is presented using successive sampling of the local current density of the beam by a modified Faraday cup. The data processing and evaluation of characteristic beam parameters are shown. The presented methods were verified by fourteen experiments using the electron beam welder. The methods have proven to be useful in practical evaluation of the device properties.
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Modification of coating-substrate interface character of thermally sprayed coatings using electron beam technology
Mareš, Jiří ; Moravčík, Igor (referee) ; Čížek, Jan (advisor)
Tato práce je zaměřena na modifikaci charakteru rozhraní substrát-nástřik NiCrAlY povlaků nanesených pomocí technologie vodou stabilizované plazmy na substráty z oceli S235JRC+C. Přetavení žárové vrstvy elektronovým paprskem bylo zvoleno jako technologie pro modifikaci a dvě různé modifikace byly zkoumány. V práci byl proveden pokus o stanovení vlivu modifikací na adhezní vlastnosti nástřiku. Dále jsou v práci prezentovány analýzy mikrostruktury, fázového a chemického složení a mikrotvrdosti ve stavu před a po modifikaci. Během studie bylo zjištěno, že dochází ke změnám fázového složení jak během depozice, tak během modifikace elektronovým paprskem. Modifikace elektronovým paprskem způsobila roztavení oxidů původní mikrostruktury nástřiku, které následně rekrystalizovaly na povrchu modifikované vrstvy. Dalším získaným poznatkem bylo, že dochází ke snížení mikrotvrdosti po modifikaci, což bylo způsobeno odstraněním oxidů z mikrostruktury a promícháním materiálu substrátu a původního nástřiku. Adheze nástřiků v as sprayed stavu byla kvantifikována. V případě nástřiků modifikovaných elektronovým paprskem přesná kvantifikace nebyla možná, z důvodu předčasného porušení na rozhraní nástřik-adhezivní pojivo během adhezních testů.
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Determination of properties of as-sprayed and EB-deposited coatings prepared by thermal spray technologies using scratch test and nano-indentation methods
Cének, Lukáš ; Tkachenko, Serhii (referee) ; Čížek, Jan (advisor)
Properties of samples and their coatings may be affected by the electron beam. This paper deals with the analysis of the microstructure, phase and chemical composition and the determination of mechanical characteristics of inconel steel substrate and CoNiCrAlY coatings deposited via different types of thermal spraying (HVOF, cold spray), in combination with modifications by the electron beam technology. During the study it was found that the deposition did not change the chemical composition. Further it was found that the interaction of the electron beam with the material did not change the chemical composition, but there is a change in the structure and a reduction of porosity and surface roughness, resulting in a change of mechanical properties such as decreasing hardness or increase of the modulus of elasticity.
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Structure and properties of electron beam penetration produced in steel AMS 5659
Říčan, Daniel ; Foret, Rudolf (referee) ; Kouřil, Miloslav (advisor)
This master thesis deals with the electron beam welding of the AMS 5659 steel used in industry for special hydraulic cylinders (Fig. 1). A theoretical analysis of electron beam welding and analysis of the influence of selected welding parameters on penetration characteristics are in the first part of the thesis. The second part contains an evaluation of the implemented experimental penetrations on samples of the steel in the hardened condition H1025 and after solution heat. It was also done a properties assessment of the same samples that were been hardened again. The light microscopy (SM), the scanning electron microscopy (SEM) and the measurement method of hardness according to Vickers were used for evaluation and comparison of the steel properties in the region of penetration and the heat affected zones properties.
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Electroless selective deposition of silver nanoparticles
Salajková, Zita ; Bartoš, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
Silver nanoparticles have a widespread use in the field of plasmonics. Since deposition of nanoparticles from colloidal solutions onto an exact location on a substrate is difficult, it seems advantageous to grow the nanoparticles in-situ. The presented work is focussed at selective deposition of~silver nanoparticles from colloidal solution or from solution reach of silver ions under assistance of focussed electron beams. Successful deposition could lead to growth of well defined nanostructures directly at the substrate surface. The effect of electron beam intensity to surface quality is studied (silica reduction, surface morphology) as well as effect of pH to particle properties. Outputs are used as a part in theoretical description of selective deposition and confirmed by following advanced experiments. The light assisted deposition and growth of nanostructures is described at the end of the presented work.
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