The widely different data obtained for the viscosity of molten iron and aluminum will be critically reviewed via an interlaboratory comparison and recommended values will be proposed.
Wide ranges of values of viscosity of both molten iron and aluminum are reported in the literature. The most widely used method is some form of oscillating vessel. For the oscillating cup a number of analytical techniques have been used to convert the measurements (logarithmic decrement and time period) to viscosity.
The Roscoe equation (1958) was recommended as providing the most accurate data for molten metals. Ferriss et al (2002) have pointed out there is a missing numerator in one of the expansions and a number of workers and standard texts have quoted "1/2" but expansion shows it to be "3/2".
In a parallel development chemical engineers have adopted a set of equations for oscillating cup viscometers by Kestin and Newell. which have been rarely used for molten metals.
There are two challenges:
- Agreement about the equations used to determine the viscosity by the oscillating cup method. At present the modified Roscoe equation by Ferriss and the Kestin and Newell appear to give similar results with one laboratory’s data.
- The widely different data obtained for the viscosity of aluminum and iron need to be critically reviewed and recommended values suggested. This may result in the need for an interlaboratory comparison.
The project should lead to a consistent, internationally approved set of values for the viscosity of these two metals, as an exemplar for the field.
– Roscoe, R (1958), Proc. Phys. Soc. 72, 576
– Ferriss, D H; Quested, P N; Chapman, L A; and Day, A P (2002) "The Choice of Equations for the Measurement of Viscosity by the Oscillating Cylinder Method". Presented at ECTP, London.
Kestin, J and Newell, GF (1957) ZAMP VIII, 433
The available experimental data for the density and viscosity of liquid aluminum and iron have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of the aluminum and iron are characterized by standard deviations of 0.65 and 0.77% at the 95% confidence level respectively.
June 2005 – The final manuscript has been approved by ICTNS.
Feb 2006 – Report published in J Phys. Chem. Ref. Data, Vol. 35, No. 1, pp. 285-300, 2006