Molten Carbonates as Electrolytes: Viscosity and Transport Properties

Abstract

The melt viscosities for Li2CO3, Na2CO2, and K2CO3 as a function of temperature to 950°C have been precisely determined. The temperature dependence of the viscosities can be expressed by the Arrhenius-type equation: η = AeE/RT, the values for A(×107) and E(kcal mole−1) being respectively: Li2CO3, 141, 16.9; Na2CO3, 4.9, 25.7; K2CO3, 1.35, 29.1. The experimental values for E correspond closely to those predicted theoretically for the transport process, assuming that viscous flow is primarily controlled by migration of the carbonate ion in these melts. Electrical transport and viscous flow in carbonate and chloride melts are briefly examined. Some melt viscosities for the ternary eutectic mixture are reported, but interpretation awaits precise density data. The present results indicate that simple average fluidity relations based on pure carbonates are not likely applicable to mixtures of carbonates in the molten state. © 1963, The Electrochemical Society, Inc. All rights reserved.