Abstract
A high-temperature rheometer equipped with a graphite furnace, characterized by an air-bearing supported synchronous motor, has been enhanced by a custom-made Pt-Au concentric cylinder assembly. With this adaptation, viscosity measurements of highly fluid melts can be achieved at high temperatures, up to 1273 K. Due to the air-bearing-supported motor, this apparatus can perform measurements of extremely low torque ranging between 0.01 mu Nm and 230 mNm (resolution of 0.1 nNm), extending the typical range of viscosity measurements accessible in the present configuration to 10(-3.5)-10(3.5) Pa.s and shear rates up to 102 of s(-1). We calibrated the system with distilled water, silicone oils, and the DGG-1 standard glass. We further present new data for the viscosity of Na2CO3, K2CO3, and Li2CO3 liquids. Finally, a comparison between our results and literature data is provided, to illustrate the effect of chemical composition and oxygen fugacity on the viscosity of alkali carbonate melts, which serve as analogs for both carbonatitic melts and molten carbonates of industrial relevance. This study substantially improves the database of alkali carbonate melts and dramatically increases the accuracy with respect to previous measurement attempts. The very low viscosity range data and their temperature dependence also helps to constrain very well the activation energy of these highly fluid systems and confirms the estimate of a universal pre-exponential factor for non-Arrhenian viscosity-temperature relationships.
| Item Type: | Journal article |
|---|---|
| Faculties: | Geosciences > Department of Earth and Environmental Sciences |
| Subjects: | 500 Science > 550 Earth sciences and geology |
| ISSN: | 0003-004X |
| Language: | English |
| Item ID: | 48986 |
| Date Deposited: | 27. Apr 2018, 08:16 |
| Last Modified: | 04. Nov 2020, 13:26 |
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