Vol.
25 No. 3
May - June 2003
Recommended
Values of the Viscosity of Molten Iron and Aluminum
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: 1) 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
laboratorys data. 2) 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.
References
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.
For more
information, contact the Task Group Chairman W. A. Wakeham
<[email protected]>.
www.iupac.org/projects/2003/2003-005-1-100.html
Page
last modified 29 April 2003.
Copyright © 2002-2003 International Union of Pure and
Applied Chemistry.
Questions regarding the website, please contact [email protected]
|