Viscosity temperature relations in the glass system SiO2-Al2O3-Na2O-K2O-CaO-MgO in the composition range of technical glasses


T. Lakatos, L.-G. Johansson and B. Simmingsköld


Glass Technology, vol. 13, no. 3, June 1972, pp 88-95


Lakatos' et al. viscosity calculation program download 40 kB, including original data




The chemical compositions of soda-lime glasses were expressed in molecular contents and in relation to 1.0 mole of silica. A balanced orthogonal latin square system was constructed with five variables at five levels of each. The temperature-viscosity curves were measured between 102 and 1013 poise.

A statistical analysis showed that if compositions are calculated on a molecular basis, the viscosity of glasses can be calculated from the composition with good accuracy (standard deviation ~3.0°C). The effects of glass constituents on viscosity are linear with the molecular contents and additives. No interaction between the glass constituents could be established. So-called anomalies exist only if the glass composition is calculated in weight percentages.

Three equations have been established for calculating the constants in the Fulcher equation from glass composition.

The viscosity model above by Lakatos et al. is based on 30 experimental data from one laboratory. After 1972 further viscosity models have been developed that consider additional data from more than one laboratory over expanded glass composition ranges.