ASTM F394-78(1996)
(Test Method)Test Method for Biaxial Flexure Strength (Modulus of Rupture) of Ceramic Substrates (Withdrawn 2001)
Test Method for Biaxial Flexure Strength (Modulus of Rupture) of Ceramic Substrates (Withdrawn 2001)
SCOPE
1.1 This test method covers the determination of the biaxial flexure strength (modulus of rupture) of thin ceramic substrates.
1.2 This test method is applicable to specimens in the as-fired condition or to test pieces prepared to have a certain thickness or surface finish.
1.3 This test method may be used with specimens of various thicknesses and having warpage; no limits are placed on the latter, except those mutually imposed by the specifications agreed upon between the manufacturer and the purchaser of the substrates.
1.4 The values stated in inch-pound units are to be regarded as the standard. The metric equivalents of inch-pound units may be approximate.
1.5 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.
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Designation: F 394 – 78 (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
Biaxial Flexure Strength (Modulus of Rupture) of Ceramic
Substrates
This standard is issued under the fixed designation F 394; 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.
−2
1. Scope 3.1.1 biaxial flexure strength, S, [FL ]—the maximum
stress in a biaxial mode of flexure that a specimen develops at
1.1 This test method covers the determination of the biaxial
rupture. This stress will normally be the calculated maximum
flexure strength (modulus of rupture) of thin ceramic sub-
radial tensile stress at the center of the convex surface. This
strates.
mode of flexure is a cupping of the circular plate caused by
1.2 This test method is applicable to specimens in the
central loading and supporting near the rim.
as-fired condition or to test pieces prepared to have a certain
3.2 Definitions of Terms Specific to This Standard:
thickness or surface finish.
−2
3.2.1 modulus of rupture (MOR), [FL ]—for this test
1.3 This test method may be used with specimens of various
method, synonymous with biaxial flexure strength.
thicknesses and having warpage; no limits are placed on the
latter, except those mutually imposed by the specifications
4. Summary of Test Method
agreed upon between the manufacturer and the purchaser of the
4.1 The test specimen, a thin circular disk, rests on three
substrates.
symmetrically spaced points near its periphery. It is bent in a
1.4 The values stated in inch-pound units are to be regarded
cupping fashion by the application of force to the center of the
as the standard. The metric equivalents of inch-pound units
disk through a cylindrical ram. The force is applied to the ram
may be approximate.
at a prescribed constant rate in a compression test machine
1.5 This standard does not purport to address all of the
until the specimen breaks. The breaking load, the dimensions
safety concerns, if any, associated with its use. It is the
and elastic constants of the specimen, and the radii of the
responsibility of the user of this standard to establish appro-
support and load are used to compute the maximum tensile
priate safety and health practices and determine the applica-
stress which is at the center of the tension (convex) surface.
bility of regulatory limitations prior to use.
This is usually the point of origin of the fracture. The computed
2. Referenced Documents or center stress then is the breaking stress (MOR). This
configuration eliminates premature fracture from an edge
2.1 ASTM Standards:
defect or anomaly.
C 623 Test Method for Young’s Modulus, Shear Modulus,
and Poisson’s Ratio for Glass and Glass-Ceramics by
5. Significance and Use
Resonance
5.1 This test method is intended for use by manufacturers
E 1 Specification for ASTM Thermometers
4 and purchasers of brittle substrates for electronic applications.
E 4 Practices for Load Verification of Testing Machines
This test method may be used for quality control (by agreement
2.2 Other Standards:
between the manufacturer and the purchaser of ceramic sub-
ACMA Test No. 2: Test Method, Flexural Strength, High
strates), or for evaluation of new materials or of new processes,
Alumina Ceramics, Alumina Ceramic Manufacturers As-
5 by comparison with known or reference materials or products.
sociation
5.2 The stress analysis applying to the configuration of this
3. Terminology test method has been covered by Kirstein and Woolley. Valid
use of the linear elastic equation to determine center stress
3.1 Definitions:
stipulates that the deflection of the plate at its center shall not
exceed one half the specimen thickness (Fig. 1); only bending
This test method is under the jurisdiction of ASTM Commitee C-21 on Ceramic
stresses are considered.
Whitewares and Related Products and is the direct responsibility of Subcommittee
5.3 Ceramic substrate materials are considered to be brittle
C21.03 on Fundamental Properties.
Current edition approved June 29, 1978. Published August 1978. Originally or perfectly elastic, that is, fracture normally occurs at the
published as F 394 – 74 T. Last previous edition F 394 – 74 T.
Annual Book of ASTM Standards, Vol 15.02.
Annual Book of ASTM Standards, Vol 14.03.
4 6
Annual Book of ASTM Standards, Vol 03.01. Kirsten, A. F., and Woolley, R. M., “Symmetrical Bending of Thin Circular
Available from Alumina Ceramic Manufacturers Assn., 331 Madison Ave., Elastic Plates on Equally Spaced Point Supports,” Journal of Research,U.S.
New York, NY 10017, Attn: George P. Byrne, Secretary. National Bureau of Standards, JNBAA, Vol 71C, 1967, pp. 1–10.
F 394
FIG. 2 Biaxial-Flexure Strength-Test Fixture
0.063-in. (1.60-mm) diameter cylinder end; this pad material
may be 0.002-in. (0.05-mm) thick polyethylene sheet.
NOTE 1—The minimum specimen thickness is required to keep the
6.4 Measuring Devices for measuring the specimen thick-
center deflection less than one half of the thickness. A value of 0.23 was
ness to the nearest 0.0001 in. or 0.002 mm, and the specimen
assumed for Poisson’s ratio, and E is Young’s modulus of elasticity of the
diameter to the nearest 0.001 in. or 0.02 mm.
test specimen.
6.5 Surface Grinder for specimen preparation as specified
FIG. 1 Estimated Minimum Specimen Thickness
in 7.2 and 7.3.
surface under a tensile stress caused by flexure. The stress is 6.6 Desiccator for specimen storage prior to testing.
termed the modulus of rupture. The modulus of rupture (MOR) 6.7 Hygrometer for measuring ambient-test relative humid-
ity to an accuracy of 65 % of the reading.
is influenced by variables associated with the procedure,
including the rate of stressing, test environment, and area of the 6.8 Thermometer for measuring ambient-test room tem-
perature. A thermometer conforming to Thermometer 63°C as
specimen subject to stress, all of which are specified in this test
method. prescribed in Specification E 1 is suitable.
6.9 Drying Oven for drying specimens after preparation at a
6. Apparatus
temperature of 150 to 200°C.
6.1 Testing Machine—Any compression-type testing ma-
6.10 Timer to time the loading period to the nearest 1 s in
chine capable of providing a uniform stress rate of 200 6 30
order to verify the stress rate.
ksi/min (19.5 to 26.4 MPa/s) as verified by Practices E 4, and
6.11 Detergent, appropriate to the substrate material and to
containing a load- or force-measuring cell having a resolution
the contamination to be removed (see 7.4).
of 0.2 % of full scale or better on a scale appropriate to the
7. Test Specimens
material under test.
6.2 Test Fixture for Supporting and Loading Specimens—A
7.1 Specimens shall be formed or cut to size by suitable
recommended fixture is shown in Fig. 2. The support points
methods (see 7.2) with care being taken that as-fired test
are provided by three ball bearings 0.125 in. (3.18 mm) in
surfaces shall be protected during processing. Specimens shall
diameter, positioned 120° apart on a 1.00 6 0.01-in. (25.2 to
be 1.250 6 0.062 in. (30.18 to 33.32 mm) in diameter.
25.6-mm) diameter circle. The load is applied to the specimen
Thickness of as-fired specimens shall not be specified except as
center by a right circular cylinder of hardened steel having a
to the minimum thickness required to limit the deflection of the
diameter of 0.063 6 0.001 in. (1.58 to 1.63 mm), with the end
specimen center to one half the specimen thickness at fracture
flat and perpendic
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