ASTM C424-93(2012)
(Test Method)Standard Test Method for Crazing Resistance of Fired Glazed Whitewares by Autoclave Treatment
Standard Test Method for Crazing Resistance of Fired Glazed Whitewares by Autoclave Treatment
SIGNIFICANCE AND USE
This test method is particularly useful for porous materials that can exhibit moisture expansion.
This test method is a primary test method that is suitable for use in specifications, quality control, and research and development. It can also serve as a referee test method in purchasing contracts or agreements.
SCOPE
1.1 This test method covers the determination of the crazing resistance of fired glazed whitewares using the autoclave treatment and under the conditions specified in this test method.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
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
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C424 − 93(Reapproved 2012)
Standard Test Method for
Crazing Resistance of Fired Glazed Whitewares by
Autoclave Treatment
This standard is issued under the fixed designation C424; 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 6 by 6 in. (152 by 152 mm) or 6 by 8 in. (152 by 200 mm). For
larger specimens, specifically tile products, five samples will
1.1 This test method covers the determination of the crazing
suffice and these may be cut to facilitate entry into the
resistance of fired glazed whitewares using the autoclave
autoclave. However, all cut pieces should be as large as
treatment and under the conditions specified in this test
possible and all cut pieces are to be tested.
method.
1.2 The values stated in inch-pound units are to be regarded
5. Procedure
as the standard. The values given in parentheses are for
5.1 Placement of Specimens in the Autoclave—Place a
information only.
sufficientamountofdistilledwaterintheautoclavesothatafter
1.3 This standard does not purport to address all of the
the test a slight excess of water will remain. Place all
safety concerns, if any, associated with its use. It is the
specimens on a suitable support at least 2 in. (51 mm) above
responsibility of the user of this standard to establish appro-
the water line within the autoclave at room temperature. Fasten
priate safety and health practices and determine the applica-
the autoclave head securely in place.
bility of regulatory limitations prior to use.
5.2 OperationofAutoclave—Gradually heat the water in the
2. Significance and Use
bottom of the autoclave. Keep the blow-off valve open for
several minutes after steam begins to escape, thereby expelling
2.1 This test method is particularly useful for porous mate-
most of the air. After closing the blow-off valve, increase the
rials that can exhibit moisture expansion.
steam pressure at a uniform rate until the desired pressure is
2.2 This test method is a primary test method that is suitable
reached within a period of not less than 45 min nor exceeding
for use in specifications, quality control, and research and
1 h. Apply sufficient heat to maintain the indicated pressure
development. It can also serve as a referee test method in
constant (62 psi (14 kPa)) for an additional hour. Shut off the
purchasing contracts or agreements.
heat source and release the steam pressure immediately by
opening the blow-off valve.
3. Apparatus
5.2.1 If it is desirable to ascertain whether failure occurs as
3.1 Autoclave—An autoclave built for a steam pressure of at
a result of rehydration only, the blow-off valve should be
least 275 psi (1.9 MPa), and preferably with sufficient capacity
cracked only and the steam released slowly over a period of 30
to contain at least ten specimens. The apparatus shall be
min. If this method of steam release is used, the report shall so
equipped with a safety valve, a blow-off valve, pressure gage
state.
measuring pressure above atmospheric pressure with an accu-
5.3 Removal of Specimens from Autoclave—Loosen the
racy of 65 psi (34 kPa), and a source of heat of sufficient
autoclave head and allow the specimens to cool in place for 30
capacity to ensure a constant steam pressure within the
min. Remove the specimens and allow to cool at room
autoclave.
temperature for an additional 30 min before examination.
4. Number of Specimens
5.4 Examination of Specimens for Crazing Failures—Use
4.1 The crazing test shall be made on at least
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