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Phase Equilibria in Systems for Lead-Free Solders
Vřešťál, J. ; Kroupa, Aleš ; Zemanová, Adéla ; Houserová, J. ; Pinkas, J.
In the year 2006,the optimization of parameters of systems Bi-Pd and Ag-In-Pd were completed by publications in articles and by addud of parameters to database COST 531. The optimisation of parameters for calculation of phase diagram of system Bi-Sb-Sn and In-Sb-Sn was performed and the results were publiced in Journal of Alloys and Compounds and parameters were added to database COST 531 and the optimisation of parameters in the system Cu-In-Sn was developing.
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Termodynamické možnosti a omezení pro výrobu čistého vodíku pomocí železa s využitím cyklického chemického procesu za nižších teplot
Svoboda, Karel ; Slowinski, G. ; Rogut, J. ; Siewiorek, A.
Iron offers possibility of transformation of a reducing gas ( CO, syngas, methane etc.) into hydrogen by a cyclic process based on iron oxide reduction and release of hydrogen in the next step by steam oxidation. Thermodynamics and chemical equilibrium for reduction of magnetite by hydrogen, carbon monoxide, model syngas and methane and for oxidation of iron by steam has been studied in a temperature range 400 – 850 K. Attention was concentrated also on possible formation of undesired soot, iron carbide and iron carbonate as precursors for CO and CO2 formation in the steam oxidation step. Oxidation of iron by steam is thermodynamically favoured at temperatures 400 – 800 K enabling high hydrogen yields. Iron oxide (magnetite) reduction is the more difficult step, requiring rather higher temperature and higher CO, H2 or methane concentrations in gaseous mixtures.
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Energetika tvorby sigma fází v Mo-X (X=Co, Cr, Fe) systémech
Houserová, Jana ; Šob, Mojmír
In systems Mo-Co, Mo-Cr and Mo-Fe, we performed calculations of the total energies of formation of all 32 possible occupations of sublattices in sigma phase structure. The optimisation of the lattice parameters of all structures was included. Sigma phases in studied systems exhibit positive values of energies of formation and it is supposed that the stability of the really existing sigma phases (i.e. Mo-Fe and Mo-Co) is due to configurational and vibrational entropies.
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Dehalogenation of Polychlorinated Biphenyls
Bureš, M. ; Pekárek, Vladimír
This work deals with the determination of the thermodynamic stability of di- to nona-chlorinated biphenyls during the dehalogenation process of these compounds in the gas phase by steam in presence of solid copper. The aim of this study is a preliminary calculation of chemical equilibrium in this dehalogenation process, which can be compared with the measured kinetics data, obtained during simulation of the technologic process. The work is connected with our previous studies, carried out with dehalogenation of polychlorinated benzenes and polychlorinated phenols.
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Thermodynamic and transport properties of ordinary water substance
Mareš, R. ; Šifner, Oldřich ; Královec, J.
A brief review of the internatonal temperature scales and its mutual conversion aids are presented. Shortly is discussed the development of new standards for the transport properties.The introduction of the new internationally adopted industrial formulation IAPWS-IF97 in the nuclear engineering practice is emphasised. Available sources of the formulation are given. Mentioned are new backward equations and TTSE method. The state in the field of the thermophysical properties of heavy water is summarized.
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