Centrifuge-assisted falling-sphere viscometry
Dorfman, Alexander; Hess, Kai-Uwe; Dingwell, Donald
European Journal of Mineralogy Volume 8 Number 3 (1996), p. 507 - 514
published: Jun 17, 1996
ArtNo. ESP147050803005, Price: 29.00 €
Abstract A method for the determination of viscosity using the falling-sphere method adapted to a high-temperature centrifuge furnace operating at > 1000 rpm is presented. Viscosity standard glass and previously well-investigated granitic melts are used to demonstrate the utility and accuracy of the method. The viscosity can be determined in a range of 105 to 108 Pa s with an accuracy (based on determinations for DGG-1 standard glass) of ± 0.09 (std. error) common log units. This method can be used to obtain melt viscosities in a range of viscosities higher than that accessible by concentric-cylinder methods and lower than that accessible by most dilatometric methods. Due to the fundamentally non-Arrhenian nature of silicate melt viscosities, data obtained with the falling-sphere centrifuge (FSC) method, taken together with viscosity data from other methods, considerably better constrain the temperature dependence of the viscosity than has been previously possible using the combination of very high and very low viscosity data alone. The fitted viscosity-temperature relations using all three types of viscosity data produce more reliable estimates of the coefficients of the Tammann-Vogel-Fulcher (TVF) fits and exclude the possibility of discontinuities in the viscosity-temperature relationships between super- and sub-liquidus data ranges.