ASTM C674-88(1999)
(Test Method)Standard Test Methods for Flexural Properties of Ceramic Whiteware Materials
Standard Test Methods for Flexural Properties of Ceramic Whiteware Materials
SCOPE
1.1 These test methods cover determination of the modulus of rupture and the modulus of elasticity of fired ceramic whitewares bodies, formed by any fabrication method, and are applicable to both glazed and unglazed test specimens.
1.2 The values stated in inch-pound units are to be regarded as the standard. The metric equivalents of inch-pound units may be approximate.
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.
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Designation:C674–88 (Reapproved 1999)
Standard Test Methods for
Flexural Properties of Ceramic Whiteware Materials
This standard is issued under the fixed designation C 674; 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 strengths of specimens intermediate of those specified, inter-
polation can be used to obtain the equivalent loading rate.
1.1 These test methods cover determination of the modulus
4.1.2 For the prescribed rectangular specimens the loading
of rupture and the modulus of elasticity of fired ceramic
rate shall be 1000 6 150 lbs (454 6 68 kg)/min.
whitewares bodies, formed by any fabrication method, and are
4.2 Bearing Edges—For the support of the test specimen,
applicable to both glazed and unglazed test specimens.
two steel (or high-strength ceramic) knife edges rounded to a
1.2 The values stated in inch-pound units are to be regarded
radius of 0.125 in. (3.18 mm) shall be provided. The load shall
as the standard. The metric equivalents of inch-pound units
be applied by means of a third steel knife edge rounded to a
may be approximate.
radius of 0.125 in. When testing rectangular specimens, the
1.3 This standard does not purport to address all of the
supporting members for the bearing edges shall be constructed
safety concerns, if any, associated with its use. It is the
to provide a means for alignment of the bearing surfaces with
responsibility of the user of this standard to establish appro-
the surfaces of the test specimen (it being possible that the
priate safety and health practices and determine the applica-
rectangular specimen may be wedge-shaped or twisted). The
bility of regulatory limitations prior to use.
apparatus shown in Figs. 1 and 2 are suggested as suitable
2. Summary of Test Methods
devices for ensuring proper spacing and alignment of the
bearing edges for rectangular test specimens.
2.1 The specimens, either cylindrical, or rectangular, are
supported on knife edges over a suitable span and a direct load
5. Test Specimens
is applied at the midpoint between the supports at a uniform
5.1 Preparation of Specimens—Form, fire, and finish the
rate until breakage occurs. The modulus of elasticity may be
specimens by the appropriate methods, following practices
determined by halting the applied load at definite intervals and
used in actual production.
measuring the deflection of the specimen at the midpoint to the
5.2 Dimensions—The specimens shall be approximately
nearest 0.001 in. (0.025 mm).
1.125 in. (28.6 mm), 0.750 in. (19.2 mm), 0.500 in. (12.7 mm),
3. Significance and Use or 0.250 in. (6.4 mm) in diameter, whichever diameter is most
comparable to that of the finished product. The length shall be
3.1 These test methods provide a means for determining the
6 6 0.50 in. (153 6 12.7 mm) to permit an overhang of at least
modulus of rupture and the modulus of elasticity, which may
0.25 in. (6.4 mm) at each end when mounted on the supports.
be required in product specifications.
Note that the 0.25-in. specimens may be 3.75 6 0.25 in. (95 6
4. Apparatus
7 mm) long.
5.2.1 The dry-pressed specimens shall be rectangular bars
4.1 Testing Machine—Any suitable testing machine may be
approximately 1 in. (25.4 mm) by 0.50 in. (12.7 mm) in cross
used, provided uniform rates of direct loading can be main-
section and at least 4.50 in. (114 mm) in length to permit an
tained.
overhang of at least 0.25 in. at each end when mounted on the
4.1.1 For all specimens the loading rate should be such that
supports.
the specimen should fail in approximately 1 min. Table 1 lists
5.3 Handling—Observe all due precautions in the forming,
loading rates that shall be used for each size specimen. For
drying, and firing to produce straight test specimens of uniform
cross section.
These test methods are under the jurisdiction of ASTM Committee C-21 on
5.4 Storage—Cool test specimens taken warm from the kiln
Ceramic Whitewares and Related Products and are the direct responsibility of
in a desiccator. If the testing must be delayed, store the bars in
Subcommittee C 21.03 on Test Methods for Whiteware Properties.
the desiccator, or in an electric oven at 110°C, and then cool in
Current edition approved Sept. 30, 1988. Published November 1988. Originally
published as C 674–71 to replace C 328 and C 369. Last previous edition C 674 –
88 (1994).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C674
TABLE 1 Loading Rates for Specimens
Nominal MOR, ksi (MPa)
Span, in. (mm) 10 (69) 30 (207) 50 (345)
Specimen Size, in. (mm)
Loading Rate, lb/min (kg/s)
1.125 (28.6) diameter 5 (127) 1100 (8.32) 3400 (25.70) 5600 (42.34)
0.750 (19.2) “ 5 (127) 300 (2.27) 1000 (7.56) 1700 (12.85)
0.500 (12.7) “ 5 (127) 100 (0.76) 300 (2.27) 500 (3.76)
0.250 (6.4) “ 3 (76) 20 (0.15) 60 (0.45) 100 (0.76)
1 by 0.50 (25.4 by 12.7) 4 (102) 400 (3.02) 1250 (9.45) 2100 (15.88)
FIG. 1 Suggested Bearing Edge and Specimen Support
FIG. 2 Alternative Suggested Bearing Edge and Specimen Support
a desiccator before testing. When removing specimens from a 6.2 Place the cylindrical specimen on the bearing edges,
hot kiln, take care to avoid thermal shock which will lead to spaced 5 in. (127 mm) 6 2 % between centers, with the
erroneous results. specimen overhanging each end by at least 0.25 in. (6.4 mm).
Apply the load at a right angle to the specimen and midway
MODULUS OF RUPTURE
(62 %) between the supporting edges. Apply the load uni-
formly at the appropriate rate for the specimen size (see 4.1.1)
6. Procedure
until failure occurs. Measure the diameter at four approxi-
6.1 Test at least ten dry specimens at room temperature.
mately equidistant points at the break and take the average to
the nearest 0.001 in. (0.0254 mm) for calculation purposes.
NOTE 1—The modulus of elasticity may be determined as described in
Break the 0.25-in. diameter rods between 3-in. (76-mm)
Sections 10-11 on the same type specimens used for the modulus of
rupture test. centers and note this in the report.
C674
6.2.1 Place the rectangular test specimen on the bearing in each laboratory tested ten specimens of each material. The
edges, spaced 4.0 in. (102 mm) between centers, with the components of variance for flexural strength results expressed
specimen overhanging at each end by at least 0.25 in. (6.4 as coefficients of variation were calculated as follows:
mm). Apply the load at a right angle to the 1-in. (25.4-mm)
Single-operator component 2.42 % of the ave
...
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