Nitride capacities in CaO–SiO₂ and CaO–SiO₂–Al₂O₃ melts

Abstract

Nitride capacities, , defined by (mass‐% N) · in the CaO–SiO 2 and CaO–SiO 2 –AI 2 O 3 melts were measured in the temperature range of 1 723 to 1 923 K by a gas‐slag equilibration technique using CaO, Al 2 O 3 , and Mo crucibles. Nitrogen content in slag, (mass‐% N), was proportional to oxygen partial pressure, , to the power of −3/4 at constant nitrogen partial pressure, . The values for increased linearly with increasing temperature and increased with the content of nitride formers, SiO 2 and Al 2 O 3 , but the effect of SiO 2 on value was found to be greater than that of Al 2 O 3 . The activity coefficients of Si 3/4 N in the CaO–SiO 2 melts tended to increase with increasing the content of SiO 2 .