ASTM C539-84(1996)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: C 539 – 84 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Linear Thermal Expansion of Porcelain Enamel and Glaze
Frits and Ceramic Whiteware Materials by Interferometric
Method
This standard is issued under the fixed designation C 539; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope index can be read to 0.002 mm (0.0001 in.).
4.3 Measuring Apparatus, consisting of fused silica inter-
1.1 This test method covers the interferometric determina-
ferometer plates, viewing apparatus, an electric furnace and
tion of linear thermal expansion of premelted frits (porcelain
control, potentiometer, pyrometer, and a suitable monochro-
enamel and glaze) and fired ceramic whiteware materials at
matic light source of known wavelength.
temperatures lower than 1000°C (1830°F).
4.3.1 Furnace—The furnace shall be a vertical electric tube
1.2 This standard does not purport to address all of the
furnace controlled by rheostat or other means so the heating
safety concerns, if any, associated with its use. It is the
rate of the furnace can be readily duplicated from room
responsibility of the user of this standard to establish appro-
temperature to 1000°C (1830°F). The heating rate shall not
priate safety and health practices and determine the applica-
exceed 3°C (5.5°F)/min.
bility of regulatory limitations prior to use.
4.3.2 Temperature Measuring Instrument—A calibrated
2. Referenced Documents platinum versus platinum-rhodium thermocouple (or a
Chromel versus Alumel thermocouple if it is frequently cali-
2.1 ASTM Standards:
brated) in conjunction with a potentiometer shall be used. The
E 289 Test Method for Linear Thermal Expansion of Rigid
potentiometer shall be capable of being read to 2°C (4°F) and
Solids with Interferometry
shall have automatic compensation for the temperature of the
3. Significance and Use
reference junction, or the reference junction shall be held at
0°C (32°F) by means of an ice bath.
3.1 This test method defines the thermal expansion of
porcelain enamel and glaze frits by the interferometric method.
5. Test Specimens
This determination is critical in avoiding crazing (cracking) of
5.1 For frit samples, three test specimens shall be prepared
these glass coatings due to mismatching of the thermal
as follows:
expansion between the coating and substrate materials.
5.1.1 Fill a No. 0 glazed porcelain crucible with frit, place
4. Apparatus
the filled crucible inside a 102-mm (4-in.) diameter fireclay
crucible partly filled with silica, and work the small crucible
4.1 Sample Preparation Equipment:
down into the silica until approximately 75 % of the small
4.1.1 Glazed Porcelain Crucible, No. 0.
crucible is below the level of the silica.
4.1.2 Fireclay Crucible, 102 mm (4 in.) in diameter.
5.1.2 Place the crucible assembly into a furnace at a
4.1.3 Rotating Abrasive Grinding Wheel (a silicon carbide
temperature high enough to just melt the mass. Hold for 15 min
type is satisfactory).
after the frit has reached the furnace temperature.
4.2 Micrometer Calipers, having a sensitivity such that the
5.1.3 Remove the crucible, rapidly transfer it to another
furnace that is at the frit firing temperature, and cool in the
This test method is under the jurisdiction of ASTM Committee B-8 on Metallic
furnace at a rate not to exceed 60°C (110°F)/h.
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
5.1.4 Break the small crucible open and break up the
Materials for Porcelain Enamel and Ceramic-Metal Systems.
Current edition approved July 27, 1984. Published September 1984. Originally vitreous mass. Select six fragments from the interior of the
published as C 539 – 64 T. Last previous edition C 539 – 78 (1983).
mass (to avoid side portions diluted by the ceramic crucible)
Annual Book of ASTM Standards, Vol 14.02.
having minimum conical dimensions of 3 mm ( ⁄8 in.) at the
An example of suitable test equipment and an inferometric method may be
base and 6 mm ( ⁄4 in.) high.
found in the paper by Merritt, G. E., “The Interference Method of Measuring
Thermal Expansion,” Journal of Research, National Institute of Standards and
5.2 For fired samples, break and select six samples having
Technology, Vol 10, No. 1, January 1933, p. 59 (RP 515). 1
minimum conical dimensions of 3 mm ( ⁄8 in.) at the base and
A description of a permissible automatic fringe recording device may be found
6mm( ⁄4 in.) in height. For all samples, grind the base of the
in the paper by Saunders, J. B., “An Apparatus for Photographing Interference
flat cones and cement the flat cone base to the flat end of a glass
Phenomenon,” Journal of Research, National Institute for Standards and Technol-
ogy, Vol 35, No. 3, September 1945, p. 157 (RP 1668).
C 539
rod with heated sealing wax. Grind the piece to a finished cone number of fringes, place the refractory ring cover on the
by rotating the rod while the piece is held against a rotating crucible and recheck for fringes.
abrasive wheel (a silicon carbide type is satisfactory).
7.3 Without rotating the crucible, gently lower it into the
5.2.1 When a reasonably symmetrical cone with a rounded
furnace and onto the bottom support so the thermocouple rests
tip is obtained, remove it from the rod by heating the wax or by
at the bottom of the crucible. Cover the top of the furnace with
pressure with the fingertips. Remove all sealing wax with a
a quartz plate.
knife blade or abrasive paper.
7.4 Rotate the telescope and check the fringe pattern. If
5.2.2 The test cone height may be of the order of 4.8 mm
excessive glare or poor contrast are present, adjust by moving
( ⁄16 in.). These bases must be smooth and flat. Use No. 0
the quartz cover, moving the light source, or releveling the
metallurgical paper to approach the desired figure and then use
telescope.
successively finer papers until the final reduction is made with
NOTE 1—Removal of the telescope eyepiece should reveal a bright dot,
a No. 3/0 paper.
which is the true image. This must be in the field or no fringes will be
seen. If this bright dot of the true image is not seen when the eyepiece is
6. Calibration of Furnace
removed, a great deal of trial and error adjustment of the telescope tripod
6.1 Using the following procedure, calibrate the furnace
must be made. A number of false images may also be present. These must
be sorted out by inserting the eyepiece and checking to see if fringes are
controls to obtain a heating rate of 3°C (5.5°F)/min:
present. If no fringes are seen, the bright dot is a false image.
6.1.1 Prepare three conical spacers closely approximating
the dimensions of the final test pieces described in Section 5.
7.5 Standardize the potentiometer if necessary and set the
These spacers shall be ground from fragments of refractory
potentiometer or other temperature measuring instrument to
ceramic known to have a softening temperature in excess of
38°C (100°F).
1000°C (1830°F).
7.6 Slowly heat the furnace to 38°C (100°F). Center the
6.1.2 Assemble the upper and lower interferometer plates
cross hair of the telescope upon any convenient fringe and
with three refractory spacers as described in Section 7, except
record the temperature corresponding to each fifth fringe.
fringe development is not necessary. Place this assembly in the
7.7 Continue heating the furnace to maintain a 3°C (5.5°F)/
furnace test location. Center the hot junction of an
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