Abstract
Abstract
The viscosities of CaO‐SiO
2
‐10wt%MgO‐20wt%Al
2
O
3
‐Na
2
O slags (CaO/SiO
2
= 0.8–1.2, wt%Na
2
O = 0–10) were measured to estimate the effect of Na
2
O on the viscous behavior at elevated temperatures. The slag viscosity at 1773 K decreased with increasing Na
2
O contents, which is observed in a basic oxide component. However, the FT‐IR spectroscopic analysis of the slag structure seemed to verify that [AlO
4
]‐tetrahedra depolymerized more readily than [SiO
4
]‐tetrahedra due to ionic charge compensation which has a tendency to be more effective on [AlO
4
]‐tetrahedra. Hence, for the present slag system, the viscosity decreased with additions of Na
2
O by providing network breaking O
2‐
ions, and the charge balance by Na
+
ions independently contributed to the depolymerization of the network structure of the molten slag. In addition, Na
2
O also lowered the critical temperature (T
CR
) resulting in a larger temperature difference between the operating temperature (T
OP
) and T
CR
, which can enhance operational stability.