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Analýza přerozdělení prvků feritických ocelí s Ni povlakem pro technologie roztavených solí
Král, Lubomír ; Čermák, Jiří ; Matal, O. ; Šimo, T. ; Nesvadba, L. ; Jílek, M.
Changes in structure and chemical composition of Ni-coated ferritic steel ČSN 411523 are studied in the present paper. The Ni-coated material is perspective for applications in molten salts technologies. The samples were subjected to corrosion in molten mixture 60 mol. % LiF + 40 mol. % NaF at temperature 953 K, the duration exposition was 100, 300 and 1000 h. Experiments were carried out in a quasidynamic regime simulating the flow of the cooling media (the mixture of molten salts) in the pipeline system. The change of chemical composition in the vicinity of interface between the Ni layer and steel substrate was measured by SEM.
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Objemová kovová skla na bázi železa - optimalizace odlévání
Stloukal, Ivo ; Král, Lubomír ; Čermák, Jiří
In this paper, the iron-based alloy was studied that is perspective for preparation of bulk metallic glass. The nominal composition of investigated material is given by the formula Fe.sub.56./sub.Co.sub.7./sub.Zr.sub.10./sub.Mo.sub.5./sub.W.sub.2./sub. B.sub.15./sub.. Two casting techniques were applied: (i) conventional casting into a copper mould in the induction furnace and (ii) casting in the arc furnace in the copper mould. In the first case, the diameter of the ingot was about 11 mm. In the second case, the special two-parts copper moulds differing in diameters of the casting inlet hole (3 and 1 mm, respectively) were used. The microstructure of alloys prepared by both techniques was studied using the light optical microscopy, SEM (Scanning Electron Microscopy) and XRD (X-ray diffraction).
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Kinetika vodíku v Mg2Ni a v hydrogenovaném eutektiku Mg-Mg2Ni
Čermák, Jiří ; Král, Lubomír ; Stloukal, Ivo
Time dependence of total amount of hydrogen desorbed from hydrogen-charged Mg and eutectic Mg-Mg2Ni (23.5 wt. % Ni) alloy was measured at temperatures from interval 552 – 723 K. Experiments were carried out well below the equilibrium pressure, where these hydrides – perspective as solid hydrogen storage media – are unstable and the desorption process is controlled mainly by diffusion of hydrogen in respective hydride (MgH2 and/or Mg2NiH4). Hydrogen diffusion coefficients were evaluated from desorption curves and hydrogen diffusion coefficient along interphase boundary MgH2/Mg2NiH4 was estimated from results obtained with the eutectic alloy.
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Strukturní změny ve slitinách Mg-Ni po absorpci a desorpci vodíku
Král, Lubomír ; Čermák, Jiří
This paper deals with changes of structure in Mg-Ni alloys after absorption and desorption of hydrogen. Experimental materials were prepared by two techniques – by casting and by ball milling and subsequent compacting to pellets. These materials were hydrogen-charged at elevated temperature and pressure. Materials were studied using the SEM Jeol JSM 6460 equipped with EDS/WDS analyzers. Formation of rectangular particles of MgNi2, nucleation of MgH2 at grain boundaries, and changes of Mg2Ni were observed. The so-called activation of hydrogen storage alloy is most likely due to fine particles that appear after the first hydrogen charging.
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The redistribution of carbon and manganese in weldments of manganese steels
Král, Lubomír ; Zlámal, B. ; Million, Bořivoj
In this paper, the results of diffusion C and Mn measurements in diffusion couples in steels with content of manganese in range 0-15 wt.% are discussed. The diffusion and thermodynamics characteristics were evaluated by using stationary model (SM). The ratio n does not agree with condition of quasistationary model (QSM) n=2 for solution of diffusion in these diffusion couples. In the paper, the results of carbon redistribution for n=2 a n= 2,8-3,7 for diffusion couples shown above are confronted each other. The part of this paper attend to more detailed description of structure changes on weldments interface in diffusion couples 0.28C-0.04Mn/0.31C- 5.01Mn a 0.28C-0.04Mn/0.34C-15.04Mn (wt.%).
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Diffusion of C and Mn in steel weldment Fe-0.3C-5Mn/Fe-0.3C-15Mn
Král, Lubomír ; Million, Bořivoj ; Čermák, Jiří
In this paper, the results of measurements of chemical diffusion of Mn and C in weldments of alloys Fe-0,3%C-5%Mn / Fe-0,3%C-15%Mn are reported. Alloys were cast in induction furnace under protective Ar atmosphere. They were hot-forged to rods of diameter 15mm and cut into pieces of 4mm thickness. These cylindrical samples were metalographical polished. Diffusion couples, welded by electrical impulse, were sealed together with Ti-chips, into evacuated silica ampoules. After that, they were annealed at 1100-800 °C for 1.5-96 hours respectively. Measurement of C redistribution was done in a normal direction to welding interface using electron-scanning microscope Philips SEM-505WDS equipped with Microspec WDX-2A. Diffusion coefficients of C and Mn were obtained and the relations between them were found.
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Multiscale design of advanced materials
Král, L. ; Million, Bořivoj
In this paper, the results of measurements of chemical diffusion of Mn in steel weldments are reported. Chemical concetnration of Mn an interval 0-15 wt.% Mn was varied. Alloys were casted in induction furnace under protective Ar atmosphere. Diffusion couples were annealed at 800-1100°C for 96-1.5 hours respectively. Measurement of Mn redistribution was done in a normal direction to welding interface using scanning electron microscope Philips SEM-505WDS equipped with Microspec WDX-2A. Diffusion coefficients of Mn were obtained by fitting experimental curves to the known analytical solution.
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Diffusion of C and Mn in steel weldment Fe-0,3C/Fe-0,3C-15Mn
Král, L. ; Million, Bořivoj ; Čermák, Jiří
In the present paper, the results of measurements of C and Mn diffusion in steel weldments of ternary alloys Fe-0.3C/Fe-0.3C-15Mn are reported. Alloys were cast in induction furnace under protective Ar atmosphere. Ingots were hot-forged to rods of the diameter 15mm and homogenized. After annealing they were machined on diameter 12mm and cut into pieces of 4mm thickness. These cylindrical samples were ground and welded by electrical impulse. Diffusion couples were sealed into evacuated silica ampoules together with Ti-chips. They were annealed at 500-1100 °C for 1.5-96 hours. Measurement of carbon and manganese redistribution was done by means line segment microanalysis in normal direction to welded interface using electron scanning microscope Philips SEM-505WDS equiped with Microspec WDX-2A. Diffusion coefficients of C and Mn were obtained and the relations between them were found.
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Mezinárodní daňové plánování
Matysová, Markéta ; Klazar, Stanislav (advisor) ; Král, Ladislav (referee)
Tato diplomová práce obsahuje všeobecný přehled o mezinárodním daňovém plánování, jeho výhodách a nevýhodách.Vysvětluje základní metody a využití mezinárodního daňového plánování. Cílem práce bylo vyčíslení daňové úspory české společnosti při využití metod daňové optimalizace, a to metody "Debt push-down merger" a metody "Deemed tax sparing credit".
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