Stability of Cuspidine (3CaO 2SiO2 CaF2) and Phase Relations in the CaO-SiO2-CaF2 System.

Abstract

Primary crystallization field of cuspidine (3CaO · 2SiO 2 · CaF 2 ) has been experimentally determined in the 2CaO · SiO 2 -SiO 2 -CaF 2 system by quenching method and differential thermal analysis (DTA). Hermetically closed platinum capsules were used as a sample container to prevent fluorine loss in the form of HF and SiF 4 by reaction of CaF 2 with moisture or SiO 2 for quenching experiments. Combining the present study with the partial phase diagrams previously reported, the whole phase diagram of the CaO-SiO 2 -CaF 2 system has been developed. Cuspidine equilibrates with (2CaO · SiO 2 ) 2 CaF 2 , CaO · SiO 2 , 3CaO · 2SiO 2 , 2CaO · SiO 2 and CaF 2 in solid state. Cuspidine coexists with liquid phases at temperatures between 1 387 K and 1 680 K.

Crystallization Behaviors of Mold Fluxes Containing Li₂O Using Single Hot Thermocouple Technique

“…If Li 2 O was substituted by Na 2 O, the following substitution reaction (1) should be taken into account according to Yasushi et al [31][32][33][34][35] But it was found that most of F Ϫ ions are fourfold coordinated by Ca 2ϩ rather than Na ϩ for samples of n Na /(n Na ϩn Ca )Յ0.3, and the presence of Na 2 O may not prevent the precipitation of cuspidine from the mold fluxes. [36][37][38][39] In the composition range of experimental samples, the value of n Na /(n Na ϩn Ca ) was less than 0.3, and it was confirmed by XRD that there was precipitation of cuspidine for all the samples. So Li 2 O substitution by Na 2 O has no effect on the crystal morphology in the crystalline film layer.…”

Influence of Na2O on Phase Relation between Mold Flux Composition and Cuspidine

“…Though thermo-dynamic data or phase diagram for cuspidine has begun to be reported recently, 6) it was not necessarily recognized as an important phase on metallurgy, and it does not exist on the phase diagram of CaO-SiO 2 -CaF 2 system. 7) Furthermore, the mold flux composition is difficult to be expressed accurately in the phase diagram because of its complication with many components, CaO, SiO 2 , Al 2 O 3 , MgO, Na 2 O, F, for examples.…”

Mold flux characterization for thin slab casting of steel

“…CaF 2 ) is one of the most important crystallized compounds in mold flux film during thin slab casting process. Watanabe et al [10] , determined the primary crystallization field and the melting temperature of cuspidine. Differential thermal analysis have been carried out in order to determine the changes in thermal properties of mold flux [11 and 12] .…”