Relation Between Viscosity and Electrical Conductivity of Silicate Melts

Abstract

The relation between viscosity and electrical conductivity of binary silicate melts is studied. The logarithm of viscosity varied linearly with the logarithm of conductivity. Furthermore, the lines are different for a MOSiO 2 system than for a M 2 O-SiO 2 system. Compared with the MO-SiO 2 system, the viscosity of the M 2 O-SiO 2 system decreases more with the increase in conductivity. Viscosity (g) is an important physicochemical property for high-temperature melts, which is closely related to metallurgical processes, such as extracting, refining, and continuous casting in steel making. Electrical conductivity (j) is another property that plays a prominent role in the modeling and operation of electric smelting furnaces. Both are sensitive to the structure change of silicate slag and exhibit an abrupt and complicated change with composition. So it is difficult to comprehend their composition dependence over wide composition ranges with only the available experimental data. Thus, pressing demands are being made for a model to estimate them over a broad composition range. Many models have been developed to predict viscosity [1][2][3][4][5][6][7][8] and electrical conductivity. [9,10] However, little research has been focused on the relationship between viscosity and electrical conductivity of silicate melts. Mills pointed out that both properties can be well correlated by the nonbridging oxygen per tetrahedrally coordinated cation (NBO/T) or revised optical basicity [11] ; therefore, some relation may exist between them. Walden's rule [12] is the first quantitative expression for viscosity and electrical conductivity, which shows that their product for an ionic liquid is constant related to the physical property of ion. However, Walden's rule is not strictly satisfied in the oxide melt because of the obvious differences between the activation energy of viscosity and the conductivity. [13] Later, Kato and Minowa [14] studied the relation in CaO-Al 2 O 3 -SiO 2 -based melts and gave the relationship in the product of gj n . Based on plenty of experimental viscosity data and the electrical conductivity model, [10] the present author gave a more accurate relation for CaO-Al 2 O 3 -SiO 2 and CaO-MgOAl 2 O 3 -SiO 2 aluminosilicate systems. [15] However, the previous studies only cover a narrow composition range in a few systems. Therefore, it is necessary to investigate whether this relations is suitable for other slag systems. Furthermore, the influence of different metal oxide on the relation between viscosity and conductivity is still unclear. In this study, MgO-SiO binary systems are studied.The viscosity and electrical conductivity of melts are structure dependent, and both change sharply as the melt structure changes. In general, the influence of different component on the melt structure is different. The acidic oxide SiO 2 can form the so-called siliconoxygen tetrahedron in which the Si cation is located at the center of the tetrahedron and oxygen anions are located at the corners. By sharing the oxygen ions, the...

Molecular dynamics simulation of the structure and properties for the CaO–SiO2 and CaO–Al2O3 systems

“…Fig. 7 shows the relation between viscosity and electrical conductivity of binary silicate melts (MO-SiO 2 systems) studied by Zhang [66] that the logarithm of viscosity varied linearly with the logarithm of conductivity (lnη = 0.15-1.10lnσ). As it can be seen that the solid squares which represent the MD simulation results of CaO-SiO 2 system are well close to the straight line, it can be concluded that the MD simulation results of viscosity and electrical conductivity for CaO-SiO 2 systems are quite convincible.…”

A Review of the Factors Affecting the Thermophysical Properties of Silicate Slags

“…The mobility of the cations will be re stricted by both the polymerised silicate network and the size of the cations (since smaller cations are more capable of squirming through the gaps in the silicate network). Several workers have equated the resistance to cation movement to the resistance to viscous flow and have correlated electrical resistivity with viscosity [57,58].…”

Modeling Viscosities of CaO-MgO-FeO-MnO-SiO2 Molten Slags

“…It has been pointed that the radius of ion also has a paradoxical effect on the electrical conductivity and that there is linear relationship between the logarithm of viscosity and the logarithm of conductivity. [52] Thus, it is not surprising that there is a paradox in the relation between viscosity and cation radius. Suginohara et al [53] measured the viscosity of PbO-SiO 2 melts with systematic substitution of alkali oxide M 2 O by alkalineearth oxide MO for PbO.…”