Viscosity Determination of Boron Oxide and Binary Borates


  • Presented at the Sixty-Third Annual Meeting, The American Ceramic Society, Toronto, Ontario, Canada, April 25, 1961 (Glass Division, No. 26-G-61).

  • Based on parts of a thesis submitted by Pei-Ching Li in partial iulfillment of the requirements for the degree of Doctor of Philosophy in chemical engineering, University of Rochester, June 1959.

  • Gouq-Jen Su is professor, Department of Chemical Engineering, University of Rochester, At the time this work was done, the other writers were graduate assistants in chemical engineering, University of Rochester. At present, Pei-Ching Li is meinber, High Temperature Materials Department, Research Division, Kaytheon Company, Waltham, Massachusetts.


The anomalous behavior of rubidium and cesium borate glass and the boron coordination in alkali borate liquids are discussed. The viscosity-composition isotherms of rubidium and cesium borates have been found to follow the same trend as those of other alkali borates. For boron oxide at temperatures between 500° and 775°C, the activation energy for viscous flow, Evis= (4.213 × 104) (1/T) - 22.15 and for temperatures above 775°C, Evis= (1.121 × 104) (1/T) + 7.40, in which T is in °K. The activation energies for viscous flow, Evis, in kcal per mole, increase with all molten alkali borates in the order Li > Na > K > Rb > Cs to about 20 mole % of akali oxide. This phenomenon is explained on the basis of Douglas's hole theory.