ASTM C1684-18

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-shaped 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.
FIG. 1 Four-Point-1/4-Point Flexure Loading Configuration  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 31-Dec-2017
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: C28 - Advanced Ceramics
• Drafting Committee: C28.01 - Mechanical Properties and Performance

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: C1684 − 18
Standard Test Method for
Flexural Strength of Advanced Ceramics at Ambient
1
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. 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 2. Referenced Documents
2
1.1 This test method is for the determination of flexural 2.1 ASTM Standards:
strength of rod-shaped specimens of advanced ceramic mate- C158 Test Methods for Strength of Glass by Flexure (De-
rials at ambient temperature. In many instances it is preferable termination of Modulus of Rupture)
to test round specimens rather than rectangular bend C1145 Terminology of Advanced Ceramics
specimens, especially if the material is fabricated in rod form. C1161 Test Method for Flexural Strength of Advanced
This method permits testing of machined, drawn, or as-fired Ceramics at Ambient Temperature
rod-shaped specimens. It allows some latitude in the rod sizes C1239 Practice for Reporting Uniaxial Strength Data and
and cross section shape uniformity. Rod diameters between 1.5 Estimating Weibull Distribution Parameters for Advanced
and 8 mm and lengths from 25 to 85 mm are recommended, but Ceramics
1
other sizes are permitted. Four-point- ⁄4-point as shown in Fig. C1322 Practice for Fractography and Characterization of
1 is the preferred testing configuration. Three-point loading is Fracture Origins in Advanced Ceramics
permitted. This method describes the apparatus, specimen C1368 Test Method for Determination of Slow Crack
requirements, test procedure, calculations, and reporting re- Growth Parameters of Advanced Ceramics by Constant
quirements. The method is applicable to monolithic or Stress-Rate Strength Testing at Ambient Temperature
particulate- or whisker-reinforced ceramics. It may also be E4 Practices for Force Verification of Testing Machines
used for glasses. It is not applicable to continuous fiber- E337 Test Method for Measuring Humidity with a Psy-
reinforced ceramic composites. chrometer (the Measurement of Wet- and Dry-Bulb Tem-
peratures)
1.2 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
3. Terminology
only.
3.1 Definitions:
1.3 This standard does not purport to address all of the
3.1.1 complete gage section, n—the portion of the specimen
safety concerns, if any, associated with its use. It is the
between the two outer loading points in four-point flexure and
responsibility of the user of this standard to establish appro-
three-point flexure fixtures. C1161
priate safety, health, and environmental practices and deter-
3.1.2 flaw, n—a structural discontinuity in an advanced
mine the applicability of regulatory limitations prior to use.
ceramic body that acts as a highly localized stress raiser.
1.4 This international standard was developed in accor-
3.1.2.1 Discussion—The presence of such discontinuities
dance with internationally recognized principles on standard-
does not necessarily imply that the ceramic has been prepared
ization established in the Decision on Principles for the
improperly or is faulty. C1322
Development of International Standards, Guides and Recom-
–2
3.1.3 flexural strength, [FL ], n—a measure of the ultimate
mendations issued by the World Trade Organization Technical
strength of a specified beam in bending. C1145, C1161
Barriers to Trade (TBT) Committee.
1
3.1.4 four-point- ⁄4-point flexure, n—configuration of flex-
ural strength testing where a specimen is symmetrically loaded
1
This test method is under the jurisdiction of ASTM Committee C28 on
Advanced Ceramics and is the direct responsibility of Subcommittee C28.01 on
2
Mechanical Properties and Performance. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2018. Published January 2018. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
ε1
approved in 2008. Last previous edition approved in 2014 as C1684 – 13 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1684-18. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
C1684 − 18
1
FIG. 1 Four-Point- ⁄4-Point Flexure Loading Configuration
at two locations that are situated one-quarter of the overall span 3.1.6.1 Discussion—An inert condition may be obtained by
away from the outer two support loading points (see Fig. 1).
using vacuum, low temperatures
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: C1684 − 13 C1684 − 18
Standard Test Method for
Flexural Strength of Advanced Ceramics at Ambient
1
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. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—Units statement was added to the scope editorially in April 2014.
1. Scope
1.1 This test method is for the determination of flexural strength of rod shape rod-shaped 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
rod-shaped specimens. It allows some latitude in the rod sizes and cross section shape uniformity. Rod diameters between 1.5 and
1
8 mm and lengths from 25 to 85 mm are recommended, but other sizes are permitted. Four-point- ⁄4 point -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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
C158 Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
C1145 Terminology of Advanced Ceramics
C1161 Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature
C1239 Practice for Reporting Uniaxial Strength Data and Estimating Weibull Distribution Parameters for Advanced Ceramics
C1322 Practice for Fractography and Characterization of Fracture Origins in Advanced Ceramics
C1368 Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate
Strength Testing at Ambient Temperature
E4 Practices for Force Verification of Testing Machines
E337 Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)
3. Terminology
3.1 Definitions:
3.1.1 complete gage section, n—the portion of the specimen between the two outer loading points in four-point flexure and
three-point flexure fixtures. C1161
3.1.2 flaw, n—a structural discontinuity in an advanced ceramic body that acts as a highly localized stress raiser.
1
This test method is under the jurisdiction of ASTM Committee C28 on Advanced Ceramics and is the direct responsibility of Subcommittee C28.01 on Mechanical
Properties and Performance.
Current edition approved Aug. 1, 2013Jan. 1, 2018. Published September 2013January 2018. Originally approved in 2008. Last previous edition approved in 20082014
ε1
as C1684 – 08.13 . DOI: 10.1520/C1684-13E01.10.1520/C1684-18.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
C1684 − 18
1
FIG. 1 Four-Point- ⁄4 Point -Point Flexure Loading Configuration
3.1.2.1 Discussion—
The presence of such discontinuities does not necessarily imply that the ceramic has been prepared improperly or is faulty. C1322
–2
3.1.3 flexural stre
...