Using the sessile drop method the wetting process of glass melts to metal plates were studied in terms of the contact angle between the solid and the melt. The experiments covered the temperature range of 550-1200°C. The change of the contact angle at constant temperature was plotted to a curve with logarithmic time scale (log
t).
Three types of wetting were found out:
(1) The results obtained at different temperatures may be superposed to from a single “master curve” by the parallel shift toward both directions along log
t-axis so that the separate curves fall on the curve of a certain standard temperature. This method is similar to the “reduced variable method” of viscoelastic bodies.
(2) Each wetting curve approaches to an eqilibrium contact angle whose values decrease with increasing temperature.
(3) A single master curve can not cover all temperature region, but above a certain temperature the separate curves assume the separate position.
The magnitude of the parallel shift necessary to form a master curve,
aT, was used to evaluate the apparent activation energy from the inclination of the straight line representing the relation log
aT vs. 1/
T. The activation energy of the wetting process was estimated to be 40-60kcal/mol, which is the same in order of magnitude as that of the viscous flow of molten glass.
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