ASTM C372-94(2020)
(Test Method)Standard Test Method for Linear Thermal Expansion of Porcelain Enamel and Glaze Frits and Fired Ceramic Whiteware Products by Dilatometer Method
Standard Test Method for Linear Thermal Expansion of Porcelain Enamel and Glaze Frits and Fired Ceramic Whiteware Products by Dilatometer Method
SIGNIFICANCE AND USE
4.1 Measurement of thermal expansion is useful for predicting stress within joined materials or single materials under conditions of changing or nonuniform temperature. It can also serve as an indicator of phase composition or changes in structure.
SCOPE
1.1 This test method covers the determination of the linear thermal expansion of premelted frit (porcelain enamel and glaze) and ceramic whiteware products by the thermal dilatometer method. This test method is applicable to apparatus meeting the reproducibility and accuracy requirements of this test method, which are to produce percent linear expansion accuracy of ±3 % or better and coefficient of linear expansion accuracy of ±5 % or better.
1.2 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C372 − 94 (Reapproved 2020)
Standard Test Method for
Linear Thermal Expansion of Porcelain Enamel and Glaze
Frits and Fired Ceramic Whiteware Products by Dilatometer
Method
This standard is issued under the fixed designation C372; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the determination of the linear 3.1 Definitions:
thermal expansion of premelted frit (porcelain enamel and 3.1.1 mean coeffıcient of linear thermal expansion—from
glaze)andceramicwhitewareproductsbythethermaldilatom- temperature T to temperature T (T < T ):
1 2 1 2
eter method. This test method is applicable to apparatus
0.01 P
α, mm/mm·°C orin./in.·°C 5
meeting the reproducibility and accuracy requirements of this
T 2 T
2 1
test method, which are to produce percent linear expansion
where:
accuracy of 63% or better and coefficient of linear expansion
accuracy of 65% or better. α = mean coefficient of linear thermal expansion from
temperature T to T , and
1 2
1.2 This standard does not purport to address all of the
P = percent linear thermal expansion as defined in 3.1.2.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.1.2 percent linear thermal expansion—from temperature
T to temperature T (T < T ):
priate safety, health, and environmental practices and deter-
1 2 1 2
mine the applicability of regulatory limitations prior to use.
L 2 L
2 1
P 5 31001A
1.3 This international standard was developed in accor-
L
dance with internationally recognized principles on standard-
∆L
ization established in the Decision on Principles for the
5 31001A
L
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical where:
Barriers to Trade (TBT) Committee.
P = percent linear thermal expansion from temperature T
to T ,
2. Referenced Documents
L = sample length at T (T between 20 and 30°C),
0 0 0
2.1 ASTM Standards: L = sample length at T ,
1 1
L = sample length at T , and
E220Test Method for Calibration of Thermocouples By
2 2
A = instrument correction.
Comparison Techniques
E228Test Method for Linear Thermal Expansion of Solid
4. Significance and Use
Materials With a Push-Rod Dilatometer
4.1 Measurementofthermalexpansionisusefulforpredict-
E230/E230MSpecification for Temperature-Electromotive
ing stress within joined materials or single materials under
Force (emf) Tables for Standardized Thermocouples
conditions of changing or nonuniform temperature. It can also
E691Practice for Conducting an Interlaboratory Study to
serve as an indicator of phase composition or changes in
Determine the Precision of a Test Method
structure.
5. Apparatus
ThistestmethodisunderthejurisdictionofASTMCommitteeC21onCeramic
Whitewares and Related Productsand is the direct responsibility of Subcommittee
5.1 Thermal Dilatometer:
C21.03 on Methods for Whitewares and Environmental Concerns.
5.1.1 General Description—A thermal dilatometer is an
Current edition approved Nov. 1, 2020. Published December 2020. Originally
apparatus that provides means for varying the temperature of a
approved in 1955. Last previous edition approved in 2016 as C372–94(2016).
DOI: 10.1520/C0372-94R20.
test specimen in a controlled manner, measuring the specimen
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
length,andmeasuringthetemperatureofthespecimenforeach
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
readingofspecimenlength.Thereareseveraldifferenttypesas
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. follows:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C372 − 94 (2020)
NOTE 1—The sample must be cooled slowly over several hours to
5.1.1.1 Manual—Amanual dilatometer is one in which any
preserve structural integrity.
oralloftheabovearedonebymanualmeansandthecorrected
percent linear thermal expansion curve is plotted by hand.
6.2 For all samples, test specimens may be of any conve-
5.1.1.2 Recording—Arecording dilatometer is an apparatus nient length, provided the uniformity of the furnace has been
bywhichtheabovearerecordedbyinstrumentalmeansbutthe
determined over that length. The minimum thickness of the
final corrected percent linear thermal expansion curve is specimen shall be 0.2 in. (5.1 mm) and the maximum cross-
2 2
plotted by hand.
sectional area shall be 0.45 in. (2.9 cm ). The ends of the
5.1.1.3 Automatic Recording—An automatic recording specimen shall be ground flat and perpendicular to the axis of
dilatometer is a recording dilatometer with provision for
the specimen.
automatically plotting the corrected percent linear thermal
6.3 Test specimens shall be conditioned in accordance with
expansion curve.
the history of the specimen. Conditioning shall include drying,
5.1.2 Any generally accepted apparatus that is capable of
annealing,orprotectionagainstmoistureexpansion,asmaybe
measuring the length changes produced by thermal expansion
necessary.
may be used in this test method. The accuracy of the
6.4 The length of the specimen shall be measured to within
expansion-measuring apparatus including transducer,
an accuracy of 0.1%.
electronic, mechanical or optical amplification and readout
device must be 60.0001 in. (60.003 mm) and should be
7. Calibration
reproducible to 60.00005 in. (60.0013 mm). A dilatometer
may use a direct method of sighting on either of the two ends
7.1 Periodiccalibrationofthethermaldilatometerisrecom-
ofthetestspecimenorsuitablemarkingsattheends,bymeans
mended to assure the accuracy required by this test method.
of two telescopes mounted on a measuring bank. Another
Procedures for calibrating the component parts of the dilatom-
method transmits the change in length of the specimen to a
eter are given below. A less time-consuming method for
sensitive dial gauge or transducer by means of members that
standardizing a complete apparatus, especially the recording
are chemically inert and free of phase transformations, having
type, is also given. A calibration check of the components of
ground and polished surfaces at points of contact with the test
theapparatusshouldbedoneonanannualbasisandcalibration
specimens.
of the complete instrument using a standard sample should be
5.2 Scale or Caliper, capable of measuring the length of the donewithin90daysprecedingareportpreparedunderthistest
specimen with an accuracy of 60.0005 in. (60.010 mm) must method.Thedateoflastcalibrationbyeithermethodshouldbe
be used. included on the report.
5.3 Furnace, electrically heated and designed so that the
7.2 Calibration Procedures:
thermal gradient over the length of the test specimen shall be
7.2.1 Dilatometer:
less than 3°C. This may be accomplished by electrical
7.2.1.1 If a direct sighting method is used, the dilatometer
shuntings, individually controlled zones, or other methods.
can be calibrated with a standard sample with a known length
5.4 Temperature-measuring Device—Temperature measure- that has been measured by a micrometer with an accuracy of
60.0001in.(0.003mm).Thereferencesampleshouldbemade
ments shall be made by means of a thermocouple placed in
from a material that has a very low thermal expansion, such as
contact with the test specimen approximately at its mid-length.
fused silica or invar. The dilatometer system can be calibrated
ThethermocoupleshallhavetheaccuracyspecifiedinTable15
by measuring the length of the sample using a movable
of Specification E230/E230M. Type S or Type K thermo-
telescope and comparing it with the known value.
couples are recommended for this test method.
7.2.1.2 If a dial gauge transducer system is used, the
5.5 Temperature-indicating Device—The temperature-
dilatometer can be calibrated with a micrometer or thickness
indicatingdevicemaybeamillivoltpotentiometer,acalibrated
gauge. Fix the dial gauge transducer and micrometer in
meterorrecorder,orotherapparatuswithaprecisionof 65°C
position on the instrument itself or in a special fixture during
and an accuracy specification equivalent to the precision.
calibration. The system can be calibrated by displacing the
6. Test Specimens
probe of the transducer a known amount with the micrometer
or thickness gauge and adjusting the instrument to give that
6.1 For frit or dried slip samples, specimens shall be
value. Whichever technique is used, the micrometer or thick-
prepared as follows:
6.1.1 Frit should be crushed and screened through a 10- ness gauge shall be accurate to 60.0001 in. (0.003 mm).
mesh sieve to remove large lumps. Then, a refractory boat 7.2.2 Furnace—The thermal gradient that occurs over the
crucible shall be filled with the sample material. If it is desired sample length within the furnace should be determined by
to reuse the crucible, it should be first lined with powdered simultaneously measuring the temperature at the center, and at
3 1
alumina as a parting agent.The crucible can be of any suitable the ends of an alumina sample ⁄8 to ⁄2 in. (10 to 13 mm) in
refractory material such as porcelain or alumina, but shall be diameter and equal in length to the standard size sample for
unglazed.Forfritsthatwillbefiredatlessthan800°C,ametal which the apparatus is intended. The thermocouples shall be
mold may be used, if desired. Type S or Type K. Thermocouple wire of 0.010-in. (0.25 mm)
6.1.2 Thetestspecimenshallbesubjectedtothesamefiring diameter or less should be used. The thermocouple beads
cycle used commercially in order to give a smooth surface on should be in contact with the test sample surface. Bring
a bulk sample. thermocouple wires out of the furnace for termination. A
C372 − 94 (2020)
commonnegativewiremaybeusedforallthreethermocouples 7.2.5.3 Plottheacceptedvaluesoftheplatinumorreference
to reduce the number of leads brought from the furnace. standard on the same graph plotted in 7.2.5.2 at no more than
Reference the center thermocouple to 0 °C and use for the
100 °C intervals.The results plotted in
...
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