TY - JOUR

T1 - Viscosity and glass transition temperature of hydrous float glass

AU - Del Gaudio, P.

AU - Behrens, H.

AU - Deubener, J.

N1 - Funding Information: This work was supported by the German Science foundation, DFG. The authors thank two anonymous reviewers for very constructive comments.

PY - 2007/3/1

Y1 - 2007/3/1

N2 - Viscosity of water-bearing float glass (0.03-4.87 wt% H2O) was measured in the temperature range of 573-1523 K and pressure range of 50-500 MPa using a parallel plate viscometer in the high viscosity range and the falling sphere method in the low viscosity range. Melt viscosity depends strongly on temperature and water content, but pressure up to 500 MPa has only minor influence. Consistent with previous studies on aluminosilicate compositions we found that the effect of dissolved water is most pronounced at low water content, but it is still noticeable at high water content. A new model for the calculation of the viscosities as a function of temperature and water content is proposed which describes the experimental data with a standard deviation of 0.22 log units. The depression of the glass transition temperature Tg by dissolved water agrees reasonably well with the prediction by the model of Deubener [J. Deubener, R. Müller, H. Behrens, G. Heide, J. Non-Cryst. Solids 330 (2003) 268]. Using water speciation measured by near-infrared spectroscopy we infer that although the effect of OH groups in reducing Tg is larger than that of H2O molecules, the difference in the contribution of both species is smaller than predicted by Deubener et al. (2003). Compared to alkalis and alkaline earth elements the effect of protons on glass fragility is small, mainly because of the relatively low concentration of OH groups (max. 1.5 wt% water dissolved as OH) in the glasses.

AB - Viscosity of water-bearing float glass (0.03-4.87 wt% H2O) was measured in the temperature range of 573-1523 K and pressure range of 50-500 MPa using a parallel plate viscometer in the high viscosity range and the falling sphere method in the low viscosity range. Melt viscosity depends strongly on temperature and water content, but pressure up to 500 MPa has only minor influence. Consistent with previous studies on aluminosilicate compositions we found that the effect of dissolved water is most pronounced at low water content, but it is still noticeable at high water content. A new model for the calculation of the viscosities as a function of temperature and water content is proposed which describes the experimental data with a standard deviation of 0.22 log units. The depression of the glass transition temperature Tg by dissolved water agrees reasonably well with the prediction by the model of Deubener [J. Deubener, R. Müller, H. Behrens, G. Heide, J. Non-Cryst. Solids 330 (2003) 268]. Using water speciation measured by near-infrared spectroscopy we infer that although the effect of OH groups in reducing Tg is larger than that of H2O molecules, the difference in the contribution of both species is smaller than predicted by Deubener et al. (2003). Compared to alkalis and alkaline earth elements the effect of protons on glass fragility is small, mainly because of the relatively low concentration of OH groups (max. 1.5 wt% water dissolved as OH) in the glasses.

KW - Alkali silicates

KW - Fragility

KW - FTIR measurements

KW - Glass transition

KW - Pressure effect

KW - Silicates

KW - Soda-lime-silica

KW - Viscosity

KW - Water in glass

UR - http://www.scopus.com/inward/record.url?scp=33846702909&partnerID=8YFLogxK

U2 - 10.1016/j.jnoncrysol.2006.11.009

DO - 10.1016/j.jnoncrysol.2006.11.009

M3 - Article

AN - SCOPUS:33846702909

VL - 353

SP - 223

EP - 236

JO - Journal of non-crystalline solids

JF - Journal of non-crystalline solids

SN - 0022-3093

IS - 3

ER -