Accurate conductivity cell for molten glasses and salts

Abstract

A cell for measuring absolute conductances of glass and salt melts is described. It is a further development of a conductivity cell reported earlier and is based on the principle that the actual cell volume within the bulk of the melt, which is contained in a platinum crucible, is enclosed by a partly immersed and open-ended alumina cell tube and is thus subjected to a defined, homogeneous electric field between two parallel platinum electrodes arranged perpendicular to the cell tube. The upper electrode positioned in the tube is cross-shaped for the removal of gas bubbles, the lower electrode is formed by a protrusion of the crucible base, which fits into the lower end of the tube. The arrangement is positioned within a specially designed resistance furnace guaranteeing temperature homogeneity of ± 1 Κ within the cell volume. The experimental reproducibility of the conductances is Δϰ ± 1.0 % and is demonstrated by three examples.