ASTM C1351M-96(2002)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C 1351M – 96 (Reapproved 2002)
METRIC
Standard Test Method for
Measurement of Viscosity of Glass Between 10 Pa·s and
10 Pa·s by Viscous Compression of a Solid Right Cylinder
[Metric]
This standard is issued under the fixed designation C1351M; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
where:
h = viscosity, Pa·s,
1.1 This test method covers the determination of the viscos-
4 8
M = applied load, g,
ity of glass from 10 Pa·s to 10 Pa·s by measuring the rate of
2 g = acceleration due to gravity, 980 cm/s ,
viscous compression of a small, solid cylinder.
t = time, s,
1.2 The values stated in SI units are to be regarded as the
V = specimen volume, cm ,
standard.
h = specimen thickness at time t, cm,
1.3 This standard does not purport to address all of the
dh/dt = compression rate, cm/s, and
safety concerns, if any, associated with its use. It is the
a = glass mean coefficient of thermal expansion, 25°C
responsibility of the user of this standard to establish appro-
to the measurement temperature, T, m/m/°C. See
priate safety and health practices and determine the applica-
Note 1.
bility of regulatory limitations prior to use.
NOTE 1—The term (1+ aT) corrects for the specimen dimensional
2. Referenced Documents
changes due to thermal expansion. For low thermal expansion glasses, it
−6
can be ignored. However, for a glass with an a of 20 310 /°C at a
2.1 ASTM Standards:
measurement temperature of 1000°C, this term produces a correction of
C338 Test Method for the Softening Point of Glass
2%. Only an estimate of a is necessary since the correction is small. Use
C965 Practice for Measuring Viscosity of GlassAbove the
twice the room temperature coefficient if data are unavailable.
Softening Point
4. Significance and Use
C1350M Test Method for Measurement of Viscosity of
Glass between the Softening Point and the Annealing
4.1 This test method is well suited for measuring the
8 13
Range (Approximately 10 Pa·s to 10 Pa·s) by Beam
viscosity of glasses between the range within which rotational
Bending
viscometry (see Practice C965) is useful and the range within
which beam bending viscometry is useful (see Test Method
3. Terminology
C 1350M). It can be used to determine the viscosity/
3.1 parallel plate viscometer—a device used to determine
temperature curve in the region near the softening point (see
4 8
the viscosity of glass from approximately 10 Pa·s to 10 Pa·s
Test Method C338). This test method is useful for providing
by measuring the rate of change in thickness of a cylindrical
information related to the behavior of glass as it is formed into
specimenbetweenparallelplatesmovingperpendiculartotheir
an object of commerce, and in research and development.
commoncentralaxis.Theequationforcalculatingviscosityby
5. Apparatus
the parallel plate method is:
5.1 The apparatus shall consist of a furnace, a means of
Mgh
h52p (1)
controlling and measuring its temperature and heating rate,
30V ~dh/dt!~2ph 1 V!~11aT!
specimen holders and loading rod, and a means of measuring
the rate of viscous compression of the glass specimen.
This test method is under the jurisdiction of ASTM Committee C14 on Glass
5.2 Furnace:
and Glass Products and is the direct responsibility of Subcommittee C14.04 on
5.2.1 The furnace shall be electrically heated by resistance
Physical and Mechanical Properties.
elements. The dimensions and details of the furnace construc-
Current edition approved Oct. 10, 1996. Published December 1996.
Fontana, E. H., “A Versatile Parallel-Plate Viscometer For Glass Viscosity
tion are not critical; its cross-section can be circular of 75 mm
Measurements to 1000°C,” Bulletin of the American Ceramic Society, Vol 49, No.
('3 in.) diameter or square of sides of 75 mm. The furnace
6, 1970, pp. 594–597.
3 should have a constant temperature zone that covers the
Annual Book of ASTM Standards, Vol 15.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1351M
specimen geometry, including the compression range. Differ-
ences in temperature greater than 2°C within the constant
temperature zone are unacceptable.
5.3 Temperature Measuring and Indicating Instruments:
5.3.1 For the measurement of temperature, there shall be
provided a calibrated Type K, R, or S thermocouple. The
thermocouple shall be housed in a double-bore alumina tube
with its junction placed within 5 mm of the specimen near the
axis of the furnace. The thermocouple shall be referenced to
0°C by means of an ice bath, and its emf measured with a
calibrated potentiometer that can be read with a sensitivity
equivalent to6 0.1°C and an accuracy of 60.5°C. Precautions
shall be taken to ensure that the ice bath is maintained at 0°C
throughoutthetest.Alternately,theoutputofthethermocouple
can be measured on a calibrated, direct reading meter (elec-
tronic thermometer) that can be read with a sensitivity of
60.1°C and an accuracy of 60.5°C. See Note 3 for tempera-
ture lag-lead corrections.
5.4 Furnace Control:
5.4.1 Suitable means shall be provided for maintaining the
furnace at a fixed control point and for controlling the heating
and cooling rates. Commercially available programming
equipment provides excellent control. A variable transformer
withmanualcontrolisaninexpensive,butlessadequatemeans
of accomplishing the required control.
5.5 Specimen Holder and Loading Rod:
5.5.1 A typical configuration is presented in Fig. 1. Posi-
tioned horizontally on top of the support stand is a stationary
plate (see Note 2), 6 mm (; ⁄4 in.) thick by diameter of the
support stand. A movable plate, 6 mm thick by 44 mm
minimum diameter is placed parallel and concentrically above
FIG. 1 A Typical Parallel Plate Viscometer
the fixed plate. (See parallel plates in Fig. 1.) Attached to the
top center of the movable plate in a shrink fit configuration is
a 9-mm (; ⁄8-in.) diameter centerless-ground alumina rod of
6. Preparation of Test Specimen
lengthsufficienttoreachapproximately150mm(6in.)beyond
the top of the furnace or its supporting structure, or both. This
6.1 Specimens required for this test method are small, right,
assembly provides a means for loading the specimen during
circular cylinders. Nominal dimensions are 6 mm (; ⁄4 in.) to
measurement. Bushings attached to the external frame guide
12mm(; ⁄2in.)diameterand3to6mmthick.Specimenscan
the shaft with a minimum amount of friction.
be either core-drilled from flat stock or sliced from a rod. In
both cases, the flat surfaces must be ground and polished to be
NOTE 2—Alumina and vitreous silica are suitable materials for the
assemblycomponents,asarenobleorlowexpansionmetalsusedinpairs.
plane-parallel to 60.001 mm. Cylinders made by dry pressing
The user must observe temperature limitations for these alternate materi-
of frit at high pressure can provide meaningful data.
als.
7. Calibration
5.6 Extensometer for Measuring Thickness Change:
5.6.1 The means of observing the rate of thickness change
7.1 Direct calibration of the apparatus is accomplished by
ofthespecimenshouldallowreliablereadingoftotalchangeof
using standard glasses, such as those supplied and certified by
at least 6 mm. The extensometer shall permit direct reading of
the National Institute of Standards and Technology (NIST),
0.010 mm and estimates of 0.001 mm. Its accuracy shall be 4
having known viscosity/temperature values. Bias should be
such that the error of indication will not exceed 62% for any
corrected by overall instrument calibration.
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