Capacitance Measurement of Molten Calcium Silicate under Shear Stress Field

Abstract

The effect of shear stress on the crystallization behavior of molten 50CaO50SiO 2 (mol%) slag was investi gated by insitu measurements of its electrical capaci tance in wide temperature range including supercooled region. It is well known that the electrical capacitance of liquids should be generally much higher than that of solids because of the differences in their respective polar ization mechanisms. The difference was employed as a sensitive indicator of the crystallization of molten silicates in an experimental furnace equipped with an electrical capacitance measurement system. The system comprised a Ptbased alloy crucible and a rotating rod that allow us to evaluate the effect of shear stress, both connected to a capacitance meter (LCR meter).As expected, at a particular temperature, the elec trical capacitance of the molten calcium silicate abruptly decreased by roughly three orders of magnitude, which clearly indicated crystallization confirmed by correspond ing microstructural analyses. It was also found that, for the rotatingrod measurements (with shear stress), the temperatures at which the capacitance abruptly dropped were higher than that without the shear stress. This sug gests that the agitation effect by the rotatingrod acceler ates the crystallization of molten calcium silicate.