ASTM C621-84(2001)
(Test Method)Standard Test Method for Isothermal Corrosion Resistance of Refractories to Molten Glass
Standard Test Method for Isothermal Corrosion Resistance of Refractories to Molten Glass
SIGNIFICANCE AND USE
This test method provides a rapid, inexpensive method for comparing the corrosion resistance of refractories. The isothermal conditions of this test method represent the most severe static corrosion environment possible at the specified test temperature. This test method is suitable for quality control, research and development applications, and for product value studies on similar materials. Tests run at a series of temperatures are often helpful in determining the use temperature limitations of a particular material. Melt-line corrosion results are also a useful indication of relative resistance to both upward and downward drilling corrosion mechanisms. Examination of test specimens also provides information about the tendency for a particular refractory to form stones or other glass defects.
Because this test method is both isothermal and static and since most glass-contact refractories operate in a dynamic system with a thermal gradient, test results do not directly predict service in a furnace. The effects of differing thermal conductivities, refractory thickness, artificial cooling or insulation upon the refractory thermal gradient, and the erosive action of moving molten glass currents are not evaluated with this test.
SCOPE
1.1 This test method covers the determination of the corrosion resistance of refractories in contact with molten glass under static, isothermal conditions.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values in parentheses are provided for information only.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:C 621–84 (Reapproved 2001)
Standard Test Method for
Isothermal Corrosion Resistance of Refractories to Molten
Glass
This standard is issued under the fixed designation C 621; 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 3.2 Because this test method is both isothermal and static
and since most glass-contact refractories operate in a dynamic
1.1 This test method covers the determination of the corro-
system with a thermal gradient, test results do not directly
sion resistance of refractories in contact with molten glass
predict service in a furnace. The effects of differing thermal
under static, isothermal conditions.
conductivities, refractory thickness, artificial cooling or insu-
1.2 The values stated in inch-pound units are to be regarded
lation upon the refractory thermal gradient, and the erosive
as the standard. The values in parentheses are provided for
action of moving molten glass currents are not evaluated with
information only.
this test.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Apparatus
responsibility of the user of this standard to establish appro-
4.1 Glass-Melting Test Furnace, heated with some type of
priate safety and health practices and determine the applica-
electrical resistor (Note 1) and having a chamber large enough
bility of regulatory limitations prior to use.
to receive four crucible assemblies of the type used in the test
2. Referenced Documents (Fig. 1) is required. The zone of the furnace in which the
crucibles will rest should possess a maximum transverse
2.1 ASTM Standards:
thermal gradient of 61.8°F (61°C). Fig. A1.1 shows a
E220 Method for Calibration of Thermocouples by Com-
schematic drawing of a furnace that is satisfactory for this test.
parison Techniques
NOTE 1—It has been demonstrated that gas-fired furnaces show greater
3. Significance and Use
variability and higher average corrosion with this test method and are
3.1 This test method provides a rapid, inexpensive method therefore generally unsuitable.
for comparing the corrosion resistance of refractories. The
4.2 Temperature-Control Instrumentation, capable of main-
isothermal conditions of this test method represent the most
taining the desired temperature to 61.8°F (61°C).
severe static corrosion environment possible at the specified
4.3 Thermocouple, for use as the temperature-measuring
test temperature. This test method is suitable for quality
device. The type of thermocouple chosen will depend on the
control, research and development applications, and for prod-
normal use temperature of the furnace. Since thermocouples
uct value studies on similar materials. Tests run at a series of
age with a consequent drift in the signal fed to the control
temperatures are often helpful in determining the use tempera-
instrument, check the couple before each test run with a
ture limitations of a particular material. Melt-line corrosion
calibrated thermocouple. Method E220 specifies calibration
resultsarealsoausefulindicationofrelativeresistancetoboth
procedures for thermocouples. If drift becomes severe, replace
upward and downward drilling corrosion mechanisms. Exami-
the thermocouple. Position the thermocouple hot junction in
nation of test specimens also provides information about the
thefurnacetocoincidewiththeleveloftheglasslineofthetest
tendency for a particular refractory to form stones or other
samples.
glass defects.
4.4 Platinum Crucibles (Fig. 1).
4.5 Sintered Zircon, or other refractory wafers (AnnexA2).
4.6 Zircon Cement (Annex A3).
4.7 Measuring Microscope.
This test method is under the jurisdiction of ASTM Committee C08 on
RefractoriesandisthedirectresponsibilityofSubcommitteeC08.10onRefractories
4.8 Tongs,suitableforhandlingsamplesinthefurnace(Fig.
for Glass.
A1.6).
Current edition approved Jan. 27, 1984. Published December 1984. Originally
4.9 Furnace, for preheating test specimens to about 1832°F
published as C621–68. Last previous edition C621–84(1995).
Discontinued. See 1994 Annual Book of ASTM Standards, Vol 14.03. (1000°C) (Annex A1).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 621–84 (2001)
5.2.1 The specimen shall be either 0.39 in. (9.9 mm) square
by 2.0 in. (51 mm) long or cylinders 0.5 in. (13 mm) in
diameterby2.0in.long.Ineithercasethespecifieddimensions
shall be controlled within 0.002 in. (0.05 mm) along the entire
length of the specimens.
5.2.2 Prepare cylindrical specimens with a diamond-core
bit. Specimens should be perfectly smooth (free of small
offsets, etc.) and free of metal marks from the drill along their
entire length. Grind square specimens to size, after diamond
sawing, on a diamond hone to provide clean parallel faces.
5.2.3 Do not grind the specimens with silicon carbide
because of the potential contaminating effect.
5.2.4 After grinding or drilling, dry the specimens to con-
stant weight at 230°F (110°C) prior to corrosion testing.
5.3 Pretest Specimen Measurements and Inspection:
5.3.1 Make a bulk density measurement on the specimen.
Calculatethevolumeofthespecimeneitherfromthespecimen
dimensions or by water displacement.
5.3.2 Measure the specimen to the nearest 0.001 in. (0.03
mm) at two points, the anticipated glass line, and at a level
halfwaybetweentheglasslineandthebottomofthespecimen.
With square specimens it is important that the orientation of
these measurements be marked above the glass line so that
corresponding measurements can be made after the test.
5.3.3 Make an inspection of the specimen prior to the test,
SI Equivalents
in. mm
noting color, evidence of porosity, and any irregularities or
0.030 0.76
unusual features.
⁄64 5
⁄2 13
5.4 Other Specimen Notes:
⁄64 13
5.4.1 Four or more specimens are usually tested concur-
⁄32 13
rently. It has been found helpful to include a control (or
1 ⁄4 32.8
standard) in each series of specimens. Ideally the control
specimens are taken from a single refractory block or shape
NOTE 1—All undesignated dimensions are in inches.
retainedsemi-permanentlyforthatpurpose.Byusingacontrol
FIG. 1 Crucible Assemblage
specimen the variability between tests can be continuously
scrutinized, and the control specimen can serve as a compari-
son standard for the other specimen in the same test.
4.10 Diamond Saw, and diamond hone, or diamond-core
drill. 5.4.2 Either round or square test specimens may be used,
but never both in the same series of experiments, since data
5. Test Specimens from the two types of specimen geometry are not directly
comparable.
5.1 Sample Selection—Asample shall be comprised of one
5.4.3 Specimen orientation within a test or series of tests
or more specimens cut from the refractory unit being tested.
shouldbeconsistent.Whenapplicable,castorpressedsurfaces
Specimens should be as representative of the material being
should comprise the sample bottom.
tested as possible. In the testing of slip-cast and pressed
refractory products, take care to avoid cracks, checks, obvious
contaminants, etc. In the testing of fusion-cast materials, it is 6. Test Temperature and Duration
recognized that wide variations in both chemistry and crystal
6.1 Test temperatures should simulate those in the intended
sizeoccurwithineverycasting.Therefore,astandardsampling
service.
locationshouldbeusedandspecified.Forflat-castblocks,take
6.2 For maximum reliability and reproducibility, the test
the specimen on the surface opposite the front scar (and
timeshouldbeofsufficientdurationtoproduceaglasslinecut
perpendicular to this surface) and at least 3 in. (76 mm) from
between 20 and 60% of the original specimen thickness.
an end and a side of the casting. For voidless castings, take the
specimenfromanycastsurfacenearthetop,saw-cutsurfaceof
7. Procedure
the block. Take this specimen at least 3 in. from any corner of
the casting. Such specimens avoid edge and corner crystalli- 7.1 Mounting Specimens—Mount specimens with the zir-
zation effects and have chemistries similar to those represent- con wafers and zircon cement and center them in the crucible
ing the bulk of the casting. as shown in Fig. 1, so the bottom of the specimen will be ⁄64
5.2 Specimen Size and Preparation: in. (5 mm) from the bottom of the crucible.
C 621–84 (2001)
with a measuring microscope, with the specimen immersed in
or coated with a liquid whose refractive index is the same as
that of the test glass.
NOTE 2—It has been established that measurement of the specimens
before splitting can result in large errors.
7.5.1 In the event of loose reaction interfaces on the test
specimens,themeasurementofremainingspecimensthickness
shall be made from the first material tig
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.