Details
| Original language | English |
|---|---|
| Pages (from-to) | 1512-1520 |
| Number of pages | 9 |
| Journal | American mineralogist |
| Volume | 84 |
| Issue number | 10 |
| Publication status | Published - 1 Oct 1999 |
Abstract
A parallel-plate viscometer has been designed for use in an internally heated pressure vessel (IHPV) at pressures up to 350 MPa and at temperatures up to 900 °C. The viscosity of a melt is determined by measuring the rate of deformation of a cylindrical sample as a function of an applied, constant stress at a fixed temperature. The viscometer consists of a small furnace with two independent heating resistors, a moveable load by which the stress is applied to the sample, and a pressure-resistant transducer (LVDT) that measures the deformation of the sample. The accessible viscosity range covers three orders of magnitude from 108.5 Pa·s to 1011.5 Pa·s. Calibration measurements on the standard melt DGG1 at 0.1 MPa demonstrated the precision of the viscometer to be within ±0.08 log units. Subsequent measurements at elevated pressure on DGG1-melt, Di100-melt (Di = CaMgSi2O6), and Ab55Di45-melt (Ab = NaAlSi3O8, composition in weight percent) showed a pronounced increase of viscosity with pressure. Comparison with literature data on the pressure dependence of the transformation temperature of Di100-melt (Rosenhauer et al. 1979) confirmed the reliability of these findings. The dependence on pressure becomes smaller with increasing temperature for these depolymerized melts; e.g., in the case of Di100-melt (NBO/T = 2) from dη/dP = +0.23 log units/100 MPa at 751 °C to dη/dP = +0.18 log units/100 MPa at 770 °C. In contrast to the depolymerized melts, a polymerized melt of haplotonalitic composition (NBO/T = 0) shows a decrease by -0.12 log units/100 MPa in the pressure range 50-350 MPa at 889 °C. Possible application of the new viscometer to study rheological properties of volatile-bearing melts was tested successfully with a hydrous haplotonalitic melt. Addition of 3.80 wt% of water to the anhydrous melt strongly shifts the viscosity-temperature relationship toward lower temperatures; e.g., at a viscosity of 1010.5 Pa·s from 883 to 515 °C. The measured viscosities did not drift during the run, indicating that water loss in negligible within the time scale of the experiments, as confirmed by IR-microspectroscopic analysis.
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
Cite this
- Standard
- Harvard
- Apa
- Vancouver
- BibTeX
- RIS
In: American mineralogist, Vol. 84, No. 10, 01.10.1999, p. 1512-1520.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Determination of the influence of pressure and dissolved water on the viscosity of highly viscous melts
T2 - Application of a new parallel-plate viscometer
AU - Schulze, Frank
AU - Behrens, Harald
AU - Hurkuck, Willy
PY - 1999/10/1
Y1 - 1999/10/1
N2 - A parallel-plate viscometer has been designed for use in an internally heated pressure vessel (IHPV) at pressures up to 350 MPa and at temperatures up to 900 °C. The viscosity of a melt is determined by measuring the rate of deformation of a cylindrical sample as a function of an applied, constant stress at a fixed temperature. The viscometer consists of a small furnace with two independent heating resistors, a moveable load by which the stress is applied to the sample, and a pressure-resistant transducer (LVDT) that measures the deformation of the sample. The accessible viscosity range covers three orders of magnitude from 108.5 Pa·s to 1011.5 Pa·s. Calibration measurements on the standard melt DGG1 at 0.1 MPa demonstrated the precision of the viscometer to be within ±0.08 log units. Subsequent measurements at elevated pressure on DGG1-melt, Di100-melt (Di = CaMgSi2O6), and Ab55Di45-melt (Ab = NaAlSi3O8, composition in weight percent) showed a pronounced increase of viscosity with pressure. Comparison with literature data on the pressure dependence of the transformation temperature of Di100-melt (Rosenhauer et al. 1979) confirmed the reliability of these findings. The dependence on pressure becomes smaller with increasing temperature for these depolymerized melts; e.g., in the case of Di100-melt (NBO/T = 2) from dη/dP = +0.23 log units/100 MPa at 751 °C to dη/dP = +0.18 log units/100 MPa at 770 °C. In contrast to the depolymerized melts, a polymerized melt of haplotonalitic composition (NBO/T = 0) shows a decrease by -0.12 log units/100 MPa in the pressure range 50-350 MPa at 889 °C. Possible application of the new viscometer to study rheological properties of volatile-bearing melts was tested successfully with a hydrous haplotonalitic melt. Addition of 3.80 wt% of water to the anhydrous melt strongly shifts the viscosity-temperature relationship toward lower temperatures; e.g., at a viscosity of 1010.5 Pa·s from 883 to 515 °C. The measured viscosities did not drift during the run, indicating that water loss in negligible within the time scale of the experiments, as confirmed by IR-microspectroscopic analysis.
AB - A parallel-plate viscometer has been designed for use in an internally heated pressure vessel (IHPV) at pressures up to 350 MPa and at temperatures up to 900 °C. The viscosity of a melt is determined by measuring the rate of deformation of a cylindrical sample as a function of an applied, constant stress at a fixed temperature. The viscometer consists of a small furnace with two independent heating resistors, a moveable load by which the stress is applied to the sample, and a pressure-resistant transducer (LVDT) that measures the deformation of the sample. The accessible viscosity range covers three orders of magnitude from 108.5 Pa·s to 1011.5 Pa·s. Calibration measurements on the standard melt DGG1 at 0.1 MPa demonstrated the precision of the viscometer to be within ±0.08 log units. Subsequent measurements at elevated pressure on DGG1-melt, Di100-melt (Di = CaMgSi2O6), and Ab55Di45-melt (Ab = NaAlSi3O8, composition in weight percent) showed a pronounced increase of viscosity with pressure. Comparison with literature data on the pressure dependence of the transformation temperature of Di100-melt (Rosenhauer et al. 1979) confirmed the reliability of these findings. The dependence on pressure becomes smaller with increasing temperature for these depolymerized melts; e.g., in the case of Di100-melt (NBO/T = 2) from dη/dP = +0.23 log units/100 MPa at 751 °C to dη/dP = +0.18 log units/100 MPa at 770 °C. In contrast to the depolymerized melts, a polymerized melt of haplotonalitic composition (NBO/T = 0) shows a decrease by -0.12 log units/100 MPa in the pressure range 50-350 MPa at 889 °C. Possible application of the new viscometer to study rheological properties of volatile-bearing melts was tested successfully with a hydrous haplotonalitic melt. Addition of 3.80 wt% of water to the anhydrous melt strongly shifts the viscosity-temperature relationship toward lower temperatures; e.g., at a viscosity of 1010.5 Pa·s from 883 to 515 °C. The measured viscosities did not drift during the run, indicating that water loss in negligible within the time scale of the experiments, as confirmed by IR-microspectroscopic analysis.
UR - http://www.scopus.com/inward/record.url?scp=0033387784&partnerID=8YFLogxK
U2 - 10.2138/am-1999-1004
DO - 10.2138/am-1999-1004
M3 - Article
AN - SCOPUS:0033387784
VL - 84
SP - 1512
EP - 1520
JO - American mineralogist
JF - American mineralogist
SN - 0003-004X
IS - 10
ER -