Abstract
The surface tension, density and viscosity coefficient of PbO-SiO2-Li2O ternary melts have been measured in the temperature range 800° to 1200°C by the use of the dipping cylinder method, the Archimedean method and the counter-sphere method, respectively.
In the (PbO·SiO2)-Li2O pseudo binary system, the surface tension decreases with the addition of Li2O. The characteristic phenomenon may be explained in terms of the production of a homopolar Pb-O bond in the melt with the addition of Li2O.
The negative deviation of molar volume from the additivity and the decrement of viscosity coefficient with the addition of Li2O indicate the bond breaking of SiO2 network and the production of descrete anions.
Logarithm of viscosity, logη, shows a linear relation with 1⁄T2 rather than with 1⁄T. The apparent activation energy of viscous flow decreases with increasing Li2O content for the (PbO·SiO2)-Li2O and (PbO·SiO2)-(Li2O·SiO2) systems.
