Ceramics-Silikáty 22, (1) 19 - 33 (1978) |
|
THE EFFECT OF NaPO₃ ON PHASE COMPOSITION IN THE SYSTEM MgO-CaO-SiO₂-Fe₂O₃–Al₂O₃-Na₂O.P₂O₅ IN RELATION TO BASIC REFRACTORIES
|
Kaprálik Ivan 1, Potančok Miroslav 2
|
1 Institute of Inorganic Chemistry, Slovak Academy of Sciences, 809 34 Bratislava, Dúbravská cesta 5
2 Slovak Technical University, Department of Chemical Technology of Silicates, 880 37 Bratislava, Jánská 1
|
The concentration part of the system MgO-CaO-SiO₂-Fe₂O₃-Al₂O₃-Na₂O.P₂O₅, which always contains the MgO phase, was found to contain 3 phosphate compounds, namely MgNaPO₄, MgCaNa₂(PO₄)₂ and CaNaPO₄ in co-existence with the adjacent phases at subsolidus temperatures. NaPO₃ reacts preferentially with CaO, either free or bound to low-melting Ca-phases and in the system there arises high-melting CaNaPO₄ which forms solid solution Ca2-xNax(PO₄)x(SiO₄)1-x.
In terms of rising NaPO₃ concentration the system was found to contain 14 independent 6-phase combinations of univariant equilibria, the MgO phase of which is still thermodynamically stable with the phosphate phases mentioned above. The subsystem MgO-2CaO.SiO₂-MgO.Al₂O₃-MgO.Fe₂O₃-2CaO.Na₂O.P₂O₅ represents a limiting cross section through the optimum NaPO₃ concentrations in the main system MgO-CaO-SiO₂-Fe₂O₃–Al₂O₃-Na₂O.P₂O₅ which is significant from the point of view of phosphate bond in basic refractories.
|
 PDF (1.4 MB) |
|
