TPWJ, 2015, #1, 24-28 pages
PREDICTION OF THERMODYNAMIC PROPERTIES OF Al2O3-SiO2 SYSTEM MELTS
Journal The Paton Welding Journal
Publisher International Association «Welding»
ISSN 0957-798X (print)
Issue № 1, 2015 (January)
I.A. Goncharov1, V.I. Galinich1, D.D. Mishchenko1 And V.S. Sudavtsova2
E.O. Paton Electric Welding Institute, NASU. 11 Bozhenko Str., 03680, Kiev, Ukraine. E-mail: firstname.lastname@example.org
I.M. Frantsevich Institute of Problems of Materials Science, NASU. 3 Krzhizhanovsky Str., 03680, Kiev, Ukraine
Aluminium and silicon oxides are included into the composition of fluxes for welding, electroslag remelting and metallurgical slags. Knowledge of thermodynamic properties of aluminium oxide-silicon oxide system mixtures will allow evaluation of the nature of their interaction in the melt that will provide an insight into the metallurgical properties of the respective materials for welding and related technologies developed on their base. Analysis of published data on phase equilibria of constitutional diagrams of aluminium oxide-silicon oxide system and thermodynamic properties of this system was performed. It is established that the constitutional diagram data are correct, and experimental values of activities of these melt components are characterized by large scatter. The coordinates of liquidus line of the constitutional diagram of aluminium oxide-silicon oxide system were used to calculate the thermodynamic activities of aluminium oxide at its concentration in the range of 0.7-1.0. It is established that they start manifesting small negative deviations from ideal solutions in the eutectic melt (0.74). Integration of Gibbs-Dugem equation was performed to assess the activities of silicon oxide. It was determined that they demonstrate slight negative deviations from ideal solutions. It is shown that the influence of aluminium oxide-silicon oxide system melts on the nature of interaction in complex multicomponent solutions can be significant. It is found that addition of thermodynamically stable chemical compounds (for instance, sillimanite) to multicomponent slag melts leads to lowering of their oxidizing ability. Replacement of quartz sand and alumina by disthen-sillimanite concentrate in agglomerated flux charge leads to lowering of thermodynamic activity of oxygen in the slag melt, slows down running of silicon-reduction process and reduces manganese losses in welding. 25 Ref., 6 Figures.
aluminium and silicon oxides, constitutional diagrams, thermodynamic activity of components, slag melts, fluxes for welding and electroslag remelting
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