ASTM C1684-13e1
(Test Method)Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature—Cylindrical Rod Strength
Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature—Cylindrical Rod Strength
SIGNIFICANCE AND USE
4.1 This test method may be used for material development, quality control, characterization, and design data generation purposes. This test method is intended to be used with ceramics whose strength is 50 MPa (~7 ksi) or greater. The test method may also be used with glass test specimens, although Test Methods C158 is specifically designed to be used for glasses. This test method may be used with machined, drawn, extruded, and as-fired round specimens. This test method may be used with specimens that have elliptical cross section geometries.
4.2 The flexure strength is computed based on simple beam theory with assumptions that the material is isotropic and homogeneous, the moduli of elasticity in tension and compression are identical, and the material is linearly elastic. The average grain size should be no greater than one fiftieth of the rod diameter. The homogeneity and isotropy assumptions in the standard rule out the use of this test for continuous fiber-reinforced ceramics.
4.3 Flexural strength of a group of test specimens is influenced by several parameters associated with the test procedure. Such factors include the loading rate, test environment, specimen size, specimen preparation, and test fixtures (1-3).3 This method includes specific specimen-fixture size combinations, but permits alternative configurations within specified limits. These combinations were chosen to be practical, to minimize experimental error, and permit easy comparison of cylindrical rod strengths with data for other configurations. Equations for the Weibull effective volume and Weibull effective surface are included.
4.4 The flexural strength of a ceramic material is dependent on both its inherent resistance to fracture and the size and severity of flaws in the material. Flaws in rods may be intrinsically volume-distributed throughout the bulk. Some of these flaws by chance may be located at or near the outer surface. Flaws may alternatively be intrinsically surface-distrib...
SCOPE
1.1 This test method is for the determination of flexural strength of rod shape specimens of advanced ceramic materials at ambient temperature. In many instances it is preferable to test round specimens rather than rectangular bend specimens, especially if the material is fabricated in rod form. This method permits testing of machined, drawn, or as-fired rod shaped specimens. It allows some latitude in the rod sizes and cross section shape uniformity. Rod diameters between 1.5 and 8 mm and lengths from 25 to 85 mm are recommended, but other sizes are permitted. Four-point-1/4 point as shown in Fig. 1 is the preferred testing configuration. Three-point loading is permitted. This method describes the apparatus, specimen requirements, test procedure, calculations, and reporting requirements. The method is applicable to monolithic or particulate- or whisker-reinforced ceramics. It may also be used for glasses. It is not applicable to continuous fiber-reinforced ceramic composites.
1.2 The values stated in SI 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)
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Designation: C1684 − 13
Standard Test Method for
Flexural Strength of Advanced Ceramics at Ambient
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Temperature—Cylindrical Rod Strength
This standard is issued under the fixed designation C1684; 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 (´) indicates an editorial change since the last revision or reapproval.
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ε NOTE—Units statement was added to the scope editorially in April 2014.
1. Scope termination of Modulus of Rupture)
C1145Terminology of Advanced Ceramics
1.1 This test method is for the determination of flexural
C1161Test Method for Flexural Strength of Advanced
strengthofrodshapespecimensofadvancedceramicmaterials
Ceramics at Ambient Temperature
at ambient temperature. In many instances it is preferable to
C1239Practice for Reporting Uniaxial Strength Data and
test round specimens rather than rectangular bend specimens,
Estimating Weibull Distribution Parameters forAdvanced
especiallyifthematerialisfabricatedinrodform.Thismethod
Ceramics
permits testing of machined, drawn, or as-fired rod shaped
C1322Practice for Fractography and Characterization of
specimens. It allows some latitude in the rod sizes and cross
Fracture Origins in Advanced Ceramics
sectionshapeuniformity.Roddiametersbetween1.5and8mm
C1368 Test Method for Determination of Slow Crack
and lengths from 25 to 85 mm are recommended, but other
Growth Parameters of Advanced Ceramics by Constant
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sizes are permitted. Four-point- ⁄4 point as shown in Fig. 1 is
Stress-Rate Strength Testing at Ambient Temperature
the preferred testing configuration. Three-point loading is
E4Practices for Force Verification of Testing Machines
permitted. This method describes the apparatus, specimen
E337Test Method for Measuring Humidity with a Psy-
requirements, test procedure, calculations, and reporting re-
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
quirements. The method is applicable to monolithic or
peratures)
particulate- or whisker-reinforced ceramics. It may also be
used for glasses. It is not applicable to continuous fiber-
3. Terminology
reinforced ceramic composites.
3.1 Definitions:
1.2 The values stated in SI units are to be regarded as the
3.1.1 complete gage section, n—theportionofthespecimen
standard. The values given in parentheses are for information
between the two outer loading points in four-point flexure and
only.
three-point flexure fixtures. C1161
1.3 This standard does not purport to address all of the
3.1.2 flaw, n—a structural discontinuity in an advanced
safety concerns, if any, associated with its use. It is the
ceramic body that acts as a highly localized stress raiser.
responsibility of the user of this standard to establish appro-
3.1.2.1 Discussion—The presence of such discontinuities
priate safety and health practices and determine the applica-
does not necessarily imply that the ceramic has been prepared
bility of regulatory limitations prior to use.
improperly or is faulty. C1322
3.1.3 flexural strength, n—a measure of the ultimate
2. Referenced Documents
strength of a specified beam in bending. C1145, C1161
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2.1 ASTM Standards:
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3.1.4 four-point- ⁄4 point flexure, n—configuration of flex-
C158Test Methods for Strength of Glass by Flexure (De-
uralstrengthtestingwhereaspecimenissymmetricallyloaded
attwolocationsthataresituatedonequarteroftheoverallspan
away from the outer two support loading points (see Fig. 1).
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This test method is under the jurisdiction of ASTM Committee C28 on
C1145, C1161
Advanced Ceramics and is the direct responsibility of Subcommittee C28.01 on
Mechanical Properties and Performance.
3.1.5 fracture origin, n—the source from which brittle
Current edition approved Aug. 1, 2013. Published September 2013. Originally
fracture commences. C1145, C1322
approved in 2008. Last previous edition approved in 2008 as C1684 – 08. DOI:
10.1520/C1684-13E01.
3.1.6 inert flexural strength, n—ameasureofthestrengthof
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
specifiedbeaminbendingasdeterminedinanappropriateinert
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
condition whereby no slow crack growth occurs.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 3.1.6.1 Discussion—An inert condition may be obtained by
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C1684 − 13
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FIG. 1 Four-Point- ⁄4 Point Flexure Loading Configuration
using vacuum, low temperatures, very fast test rates, or any 3.1.10 three-point flexure, n—configuration of flexural
inert media.
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