Nitride capacities of CaO-Al2O3-CaF2 melts at 1 773 K

The nitrogen solubility of CaO-Al2O3-CaF2 was studied at 1 773 K. It was fo und that nitride capacity increased with increasing CaO content for a given CaF2/Al2O3 ratio, decreased with increasing Al2O3 content for a given CaO/ CaF2 ratio, and increases with increasing CaF2 content when the CaO/Al2O3 m olar ratio was less than about 2, but became unaffected by CaF2 content whe n the ratio exceeded about 2. These observations were interpreted that CaO depolymerized the Al2O3 network, allowing for nitrogen to exist as both fre e and non-bridging nitrides, and that CaF, assisted in depolymerization and hence increased nitrogen solubility, provided that there was a sufficient amount of network to be depolymerized. A diagram of iso-nitride capacity wa s drawn for the CaO-Al2O3-CaF2 ternary system at 1 773 K, and the nitride c apacity was related to the optical basicity of the melt to obtain the follo wing correlation equation: