Crystallization behavior of supercooled calcium silicate based slags were systematically investigated by the measurement of their electrical capacitance. It is well known that the electrical capacitance of liquids is generally much higher than that of solids owing to the differences in their respective polarization mechanisms. These differences were exploited as a sensitive indicator of the crystallization of molten calcium silicates. As expected, at a particular temperature, the electrical capacitance of the molten calcium silicates underwent a precipitous decrease by roughly three orders of magnitude, which was dependent on the chemical composition. This indicated the presence of crystallization and this was confirmed by corresponding microstructural characterization. It was also found that, for the measurements acquired with rotating rod agitation, the temperatures at which the capacitance underwent the sharp decrease were higher than that identified without the agitation. This suggests that the agitation effect accelerates the crystallization of molten calcium silicates
Noritaka Saito is an associate professor in the Department of Materials Engineering at Kyushu University, Japan. He specialises in physical chemistry of high temperature melts and related pyro-processing for advanced glasses and ceramics. His research interests have included partial liquid phase bonding of advanced ceramics and diffusion phenomena at the bonding interface, fabrication of translucent alumina and yttria ceramics, and evaluation of viscosity and crystallization behavior of oxide melts at high temperature.