Effects of Agitation and Morphology of Primary Crystalline Phase on Crystallization Behavior of CaO-SiO2-CaF2 Supercooled Melts

The effects of the agitation field and the crystal morphology on the primary and secondary crystallization temperatures of CaO-SiO2-CaF2 supercooled melts were systematically investigated by measuring the electrical capacitance. Two-stage decreases in electrical capacitance were observed for most samples investigated. These stages correspond to the primary crystallization and the eutectic reaction resulting from the compositional change in the supercooled melts associated with the primary crystallization, respectively. The primary crystallization of dendritic CaO center dot SiO2 was affected by the agitation in the same manner as reported previously, but the crystallization of faceted 3CaO center dot 2SiO(2)center dot CaF2 revealed little dependence on the agitation. This indicates that the effects of the agitation are different for different morphologies of the primary crystalline phase because of shifts in the rate-determining step of crystallization.