ASTM C1350M-96(2008)

Standard Test Method for Measurement of Viscosity of Glass Between Softening Point and Annealing Range (Approximately 10⁸ Pa·s to Approximately 10 ¹³ Pa·s) by Beam Bending (Metric)

SIGNIFICANCE AND USE
This test method is well suited for measuring the viscosity of glasses in ranges higher than those covered by parallel plate (see Test Method C 1351) and rotational viscometry (see Practice C 965) methods. This test method is useful for providing information related to the behavior of glass after it has been formed into an object of commerce and in research and development.
SCOPE
1.1 This test method covers the determination of glass viscosity from approximately 108 Pa·s to approximately 10 13  Pa·s by measuring the rate of viscous bending of a simply loaded glass beam. Due to the thermal history of the glass, the viscosity may not represent conditions of thermal equilibrium at the high end of the measured viscosity range. Measurements carried out over extended periods of time at any temperature or thermal preconditioning will minimize these effects by allowing the glass to approach equilibrium structural conditions. Conversely, the method also may be used in experimental programs that focus on nonequilibrium conditions.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Mar-2008
• ICS: 81.040.01 - Glass in general
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.04 - Physical and Mechanical Properties

Relations

• Replaces: ASTM C1350M-96(2003) - Standard Test Method for Measurement of Viscosity of Glass Between Softening Point and Annealing Range (Approximately 10⁸ Pa·s to Approximately 10 ¹³ Pa·s) by Beam Bending (Metric)
• Effective Date: 01-Apr-2008
• Replaced By: ASTM C1350M-96(2013) - Standard Test Method for Measurement of Viscosity of Glass Between Softening Point and Annealing Range (Approximately 10⁸ Pa·s to Approximately 10¹³ Pa·s) by Beam Bending (Metric)
• Effective Date: 01-Oct-2013
• Referred By: ASTM C1351M-96(2022) - Standard Test Method for Measurement of Viscosity of Glass Between 10⁴ Pa·s and 10⁸ Pa·s by Viscous Compression of a Solid Right Cylinder [Metric]
• Effective Date: 01-Apr-2008

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C1350M − 96(Reapproved 2008)
Standard Test Method for
Measurement of Viscosity of Glass Between Softening Point
and Annealing Range (Approximately 10 Pa·s to
13 1
Approximately 10 Pa·s) by Beam Bending (Metric)
This standard is issued under the fixed designation C1350M; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope C965 Practice for Measuring Viscosity of Glass Above the
Softening Point
1.1 This test method covers the determination of glass
8 13 C1351M Test Method for Measurement of Viscosity of
viscosity from approximately 10 Pa·s to approximately 10
4 8
Glass Between 10 Pa·s and 10 Pa·s by Viscous Com-
Pa·s by measuring the rate of viscous bending of a simply
2 pression of a Solid Right Cylinder [Metric]
loaded glass beam. Due to the thermal history of the glass, the
viscosity may not represent conditions of thermal equilibrium
3. Terminology
at the high end of the measured viscosity range. Measurements
carried out over extended periods of time at any temperature or
3.1 Definitions:
thermal preconditioning will minimize these effects by allow-
3.1.1 beam bending viscometer—a device used to determine
ing the glass to approach equilibrium structural conditions.
the viscosity of glass from approximately 10 Pa·s to approxi-
Conversely, the method also may be used in experimental
mately 10 Pa·s by measuring the deflection rate of a simply
programs that focus on nonequilibrium conditions.
supported beam. The equation for calculating viscosity by this
method is:
1.2 The values stated in SI units are to be regarded as
3 3
standard. No other units of measurement are included in this
gL ρAL 11α T
~ !
s
η 5 M1 (1)
F G
F 4G
standard.
1440 I ~dh/dt! 1.6 11α T
~ !
c g
1.3 This standard does not purport to address all of the
where:
safety concerns, if any, associated with its use. It is the
η = viscosity, Pa·s,
responsibility of the user of this standard to establish appro-
M = load (applied load + loading train), gms,
priate safety and health practices and determine the applica-
dh/dt = midpoint deflection rate of test beam, cm/s,
bility of regulatory limitations prior to use. 2
g = acceleration of gravity, 980 cm/s ,
I = cross-sectional moment of inertia, cm ,
c
2. Referenced Documents 3
ρ = density of glass, g/cm ,
2.1 ASTM Standards: A = cross-sectional area of the beam, cm ,
L = support span, cm, and
C336 Test Method for Annealing Point and Strain Point of
α and α = mean coefficient of linear thermal expansion of
Glass by Fiber Elongation s g
support stand and glass, respectively, 25°C to
C338 Test Method for Softening Point of Glass
temperature of measurement, T, m/m/°C. See
C598 Test Method for Annealing Point and Strain Point of
Note 1.
Glass by Beam Bending
3 4
NOTE 1—The term (1 +α T) /(1 +α T) corrects for thermal expansion
s g
changes of room temperature dimensions. It can be ignored when α and
s
α are approximately equal. A fused silica support stand in combination
g
This test method is under the jurisdiction of ASTM Committee C14 on Glass
with a high expansion glass can make this term 3 % in magnitude. Only
and Glass Productsand is the direct responsibility of Subcommittee C14.04 on
an estimate of α is required, singe the correction is small. Use 1.5 times
g
Physical and Mechanical Properties.
the room temperature coefficient if data are unavailable.
Current edition approved April 1, 2008. Published December 2008. Originally
approved in 1996. Last previous edition approved in 2003 as C1350M – 96 (2003).
DOI: 10.1520/C1350M-96R08.
4. Significance and Use
Hagy, H. E., “Experimental Evaluation of Beam Bending Method of Deter-
8 15
4.1 This test method is well suited for measuring the
mining Glass Viscosities in the Range 10 to 10 Poises”, Journal of the American
Ceramic Society, Vol 46, No. 2, 1963, pp. 95–97.
viscosity of glasses in ranges higher than those covered by
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
parallel plate (see Test Method C1351M) and rotational vis-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
cometry (see Practice C965) methods. This test method is
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. useful for providing information related to the behavior of
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1350M − 96 (2008)
glass after it has been formed into an object of commerce and a shepherd’s crook. This crook will contribute to the load on
in research and development. the specimen, so its weight should be kept to a minimum.
NOTE2—Vitreoussilicaisasuitablematerialforbothsupportstandand
5. Apparatus
loading rod. It is not recommended for temperatures above 900°C.
5.6 Extensometer for Measuring Midpoint Deflection:
5.1 The apparatus shall consist of a furnace, a means of
5.6.1 The means for observing the rate of deflection of the
controlling its temperature and heating rate, specimen holders
specimen shall allow reliable reading of total deflection of at
and loading rod, and a means of observing the rate of viscous
least 10 mm. The extensometer shall permit direct reading of
deflection of the glass specimen.
0.010 mm and estimates of 0.0010 mm. Its accuracy shall be
5.2 Furnace:
such that the error of indication will not exceed 62 % for any
5.2.1 The furnace shall be electrically heated by resistance
measured deflection. This will limit the minimum deflection
elements. The dimensions and the details of the furnace
that may be used in calculation.Alinearly variable differential
construction are not critical; its cross-section can be circular of
transformer (LVDT) is suitable for this purpose, as is any other
75 mm (;3 in.) diameter or square with sides of 75 mm. The
device (for example, optical or capacitive), provided that
furnace should have a constant temperature zone that covers
deflection is reliably measured as specified.
the specimen geometry, including the deflection range. Differ-
5.7 Weights:
ences in temperature greater than 2°C within that constant
5.7.1 A set of weights spanning the range from 1 to 500 g
temperature zone are unacceptable.
and accurate to 0.1 % relative is required.
5.3 Temperature Measuring and Indicating Instruments:
5.8 Micrometre Calipers:
5.3.1 For the measurement of temperature, there shall be
5.8.1 Micrometre calipers which can be read to an accuracy
provided a calibrated Type K, R, or S thermocouple. The
of at least 0.01 mm are required for measuring specimen
thermocouple shall be housed in a double-bore alumina tube
dimensions.
with its junction placed within 5 mm of the specimen near the
5.9 Analytical Balance:
axis of the furnace. The thermocouple shall be referenced to
5.9.1 An analytical balance capable of weighing the shep-
0°C by means of an ice bath, and its emf measured with a
herd’s crook and loading train to an accuracy of 0.1 % relative.
calibrated potentiometer that can be read with a sensitivity of
0.1°Candanaccuracyof 60.5°C.Precautionsshallbetakento
6. Preparation of Test Specimen
ensure that the ice bath is maintained at 0°C throughout the
6.1 Specimens may either be flame drawn or centerless
test. Alternately, the output of the thermocouple can be
ground into cylindrical form or diamond-saw cut and mill
measured on a calibrated, direct reading meter (electronic
groundintorectangularform.Nonuniformityofanydimension
thermometer) that can be read with a sensitivity of 0.1°C and
along the length of the specimen shall not exceed 2 %. When
an accuracy of 60.5°C. See Note 3 for temperature lag-lead
nonuniformity of any dimension exists, an average value shall
corrections.
be used.
5.4 Furnace Control:
6.2 The numerical ratio of beam span to moment of inertia
shall not be less than 60. The thickness or diameter to span
5.4.1 Suitable means shall be provided for maintaining the
furnace temperature at a fixed control point and for controlling ratio shall be less than 0.1.
the heating and cooling rates. Commercially available pro-
7. Calibration
gramming equipment provides excellent control. A variable
7.1 Direct calibration of the apparatus is accomplished by
transformer with manual control is an inexpensive, but less
adequate means of accomplishing the required control. using standard glasses, such as those supplied and certified by
the National Institute of Standards and Technology (NIST),
5.5 Specimen Holder and Loading Rod :
having known temperature values over the viscosity range
5.5.1 A diagram of the apparatus can be found in Test
covered by this practice. Bias should be corrected by overall
Method C598.
instrument calibration:
5.
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C1350M–96 (Reapproved 2003) Designation:C1350M–96 (Reapproved
2008)
Standard Test Method for
Measurement of Viscosity of Glass Between Softening Point
and Annealing Range (Approximately 10 Pa·s to
Approximately 10 Pa·s) by Beam Bending (Metric)
This standard is issued under the fixed designation C 1350M; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
8 13
1.1 This test method covers the determination of glass viscosity from approximately 10 Pa·s to approximately 10 Pa·s by
measuring the rate of viscous bending of a simply loaded glass beam. Due to the thermal history of the glass, the viscosity may
not represent conditions of thermal equilibrium at the high end of the measured viscosity range. Measurements carried out over
extended periods of time at any temperature or thermal preconditioning will minimize these effects by allowing the glass to
approach equilibrium structural conditions. Conversely, the method also may be used in experimental programs that focus on
nonequilibrium conditions.
1.2The values stated in SI units are to be regarded as the standard.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
C 336 Test Method for Annealing Point and Strain Point of Glass by Fiber Elongation
C 338 Test Method for Softening Point of Glass
C 598 Test Method for Annealing Point and Strain Point of Glass by Beam Bending
C 965 Practice for Measuring Viscosity of Glass Above the Softening Point
4 8
C 1351M Test Method for Measurement of Viscosity of Glass betweenBetween 10 Pa·s Pas and 10 Pa·sPas by Viscous
Compression of a Solid Right Cylinder [Metric]
3. Terminology
3.1 Definitions:
3.1.1 beam bending viscometer—adeviceusedtodeterminetheviscosityofglassfromapproximately10 Pa·stoapproximately
10 Pa·s by measuring the deflection rate of a simply supported beam. The equation for calculating viscosity by this method is:
3 3
gL rAL ~11a T!
s
h5 M 1 (1)
F GF 4G
1440 I ~dh/dt! 1.6
c ~11a T!
g
where:
h = viscosity, Pa·s,
M = load (applied load + loading train), gms,
dh/dt = midpoint deflection rate of test beam, cm/s,
g = acceleration of gravity, 980 cm/s ,
This test method is under the jurisdiction of ASTM Committee C14 on Glass and Glass Products and is the direct responsibility of Subcommittee C14.04 on Physical
and Mechanical Properties.
Current edition approved Apr. 10, 2003. Published July 2003. Originally approved in 1996. Last previous edition approved in 1996 as C 1350M–96.
Current edition approved April 1, 2008. Published December 2008. Originally approved in 1996. Last previous edition approved in 2003 as C 1350M – 96 (2003).
2 8 15
Hagy, H. E., “Experimental Evaluation of Beam Bending Method of Determining Glass Viscosities in the Range 10 to 10 Poises”, Journal of the American Ceramic
Society, Vol 46, No. 2, 1963, pp. 95–97.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
, Vol 15.02.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1350M–96 (2008)
I = cross-sectional moment of inertia, cm ,
c
r = density of glass, g/cm ,
A = cross-sectional area of the beam, cm ,
L = support span, cm, and
a and a = mean coefficient of linear thermal expansion of support stand and glass, respectively, 25°C to temperature of
s g
measurement, T, m/m/°C. See Note 1.
3 4
NOTE 1—The term (1 + a T) /(1 + a T) corrects for thermal expansion changes of room temperature dimensions. It can be ignored when a and a
s g s g
are approximately equal.Afused silica support stand in combination with a high expansion glass can make this term 3 % in magnitude. Only an estimate
of a is required, singe the correction is small. Use 1.5 times the room temperature coefficient if data are unavailable.
g
4. Significance and Use
4.1 This test method is well suited for measuring the viscosity of glasses in ranges higher than those covered by parallel plate
(see Test Method C 1351) and rotational viscometry (see Practice C 965) methods. This test method is useful for providing
information related to the behavior of glass after it has been formed into an object of commerce and in research and development.
5. Apparatus
5.1 The apparatus shall consist of a furnace, a means of controlling its temperature and heating rate, specimen holders and
loading rod, and a means of observing the rate of viscous deflection of the glass specimen.
5.2 Furnace:
5.2.1 The furnace shall be electrically heated by resistance elements.The dimensions and the details of the furnace construction
are not critical; its cross-section can be circular of 75 mm (;3 in.) diameter or square with sides of 75 mm. The furnace should
have a constant temperature zone that covers the specimen geometry, including the deflection range. Differences in temperature
greater than 2°C within that constant temperature zone are unacceptable.
5.3 Temperature Measuring and Indicating Instruments:
5.3.1 Forthemeasurementoftemperature,thereshallbeprovidedacalibratedTypeK,R,orSthermocouple.Thethermocouple
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 of 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 throughout the test.Alternately, the output of the thermocouple can be measured on a calibrated, direct reading
meter (electronic thermometer) that can be read with a sensitivity of 0.1°C and an accuracy of 60.5°C. See Note 3 for temperature
lag-lead corrections.
5.4 Furnace Control:
5.4.1 Suitable means shall be provided for maintaining the furnace temperature at a fixed control point and for controlling the
heatingandcoolingrates.Commerciallyavailableprogrammingequipmentprovidesexcellentcontrol.Avariabletransformerwith
manual control is an inexpensive, but less adequate means of accomplishing the required control.
5.5 Specimen Holder and Loading Rod :
5.5.1 A diagram of the apparatus can be found in Test Method C 598.
5.5.2 A ceramic support stand and a ceramic loading rod shall be provided for supporting the specimen and applying the load
to it.The thermal expansion characteristics of both members must be very similar so as to minimize motion of the loading rod due
to expansion differences.Arectangular alumina muffle or circular tube that can be notched to define specimen position is a suitable
support stand (see Note 2). The supporting surfaces of these notches shall be flat and lie in a plane perpendicular to the axis of
the furnace. The inside edges of these notches define the support span once the specimen beam starts to deflect. A support span
of about 5 cm (62 in.) is recommended.Asuitable loading rod can be provided by a single-crystal sapphire rod flame bent at one
end in the form of a shepherd’s crook. This crook will contribute to the load on the specimen, so its weight should be kept to a
minimum.
NOTE 2—Vitreous silica is a suitable material for both support stand and loading rod. It is not recommended for temperatures above 900°C.
5.6 Extensometer for Measuring Midpoint Deflection:
5.6.1 The means for observing the rate of deflection of the specimen shall allow reliable reading of total deflection of at least
10 mm. The extensometer shall permit direct reading of 0.010 mm and estimates of 0.0010 mm. Its accuracy shall be such that
the error of indication will not exceed 62 % for any measured deflection.This will limit the minimum deflection that may be used
in calculation.Alinearly variable differential transformer (LVDT) is suitable for this purpose, as is any other device (for example,
optical or capacitive), provided that deflection is reliably measured as specified.
5.7 Weights:
The sole source of supply of flamebent hooks known to the committee at this time is Insaco Inc., P.O. Box 422, Quakertown, PA18951. If
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