ASTM C1273-05(2010)
(Test Method)Standard Test Method for Tensile Strength of Monolithic Advanced Ceramics at Ambient Temperatures
Standard Test Method for Tensile Strength of Monolithic Advanced Ceramics at Ambient Temperatures
SIGNIFICANCE AND USE
This test method may be used for material development, material comparison, quality assurance, characterization, and design data generation.
High strength, monolithic advanced ceramic materials generally characterized by small grain sizes (50 μm) and bulk densities near the theoretical density are candidates for load-bearing structural applications requiring high degrees of wear and corrosion resistance, and high temperature strength. Although flexural test methods are commonly used to evaluate strength of advanced ceramics, the non-uniform stress distribution of the flexure test specimen limits the volume of material subjected to the maximum applied stress at fracture. Uniaxially-loaded tensile strength tests provide information on strength-limiting flaws from a greater volume of uniformly stressed material.
Although the volume or surface area of material subjected to a uniform tensile stress for a single uniaxially-loaded tensile test may be several times that of a single flexure test specimen, the need to test a statistically significant number of tensile test specimens is not obviated. Therefore, because of the probabilistic strength distributions of brittle materials such as advanced ceramics, a sufficient number of test specimens at each testing condition is required for statistical analysis and eventual design, with guidelines for sufficient numbers provided in this test method. Note that size-scaling effects as discussed in Practice C1239 will affect the strength values. Therefore, strengths obtained using different recommended tensile test specimens with different volumes or surface areas of material in the gage sections will be different due to these size differences. Resulting strength values can be scaled to an effective volume or surface area of unity as discussed in Practice C1239.
Tensile tests provide information on the strength and deformation of materials under uniaxial tensile stresses. Uniform stress states are required to effectively evalu...
SCOPE
1.1 This test method covers the determination of tensile strength under uniaxial loading of monolithic advanced ceramics at ambient temperatures. This test method addresses, but is not restricted to, various suggested test specimen geometries as listed in the appendix. In addition, test specimen fabrication methods, testing modes (force, displacement, or strain control), testing rates (force rate, stress rate, displacement rate, or strain rate), allowable bending, and data collection and reporting procedures are addressed. Note that tensile strength as used in this test method refers to the tensile strength obtained under uniaxial loading.
1.2 This test method applies primarily to advanced ceramics that macroscopically exhibit isotropic, homogeneous, continuous behavior. While this test method applies primarily to monolithic advanced ceramics, certain whisker- or particle-reinforced composite ceramics as well as certain discontinuous fiber-reinforced composite ceramics may also meet these macroscopic behavior assumptions. Generally, continuous fiber ceramic composites (CFCCs) do not macroscopically exhibit isotropic, homogeneous, continuous behavior and application of this practice to these materials is not recommended.
1.3 Values expressed in this test method are in accordance with the International System of Units (SI) and .
1.4 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. Specific precautionary statements are given in Section 7.
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Designation: C1273 − 05(Reapproved 2010)
Standard Test Method for
Tensile Strength of Monolithic Advanced Ceramics at
Ambient Temperatures
This standard is issued under the fixed designation C1273; 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.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of tensile 2.1 ASTM Standards:
strengthunderuniaxialloadingofmonolithicadvancedceram- C1145Terminology of Advanced Ceramics
ics at ambient temperatures. This test method addresses, but is C1161Test Method for Flexural Strength of Advanced
notrestrictedto,varioussuggestedtestspecimengeometriesas Ceramics at Ambient Temperature
listed in the appendix. In addition, test specimen fabrication C1239Practice for Reporting Uniaxial Strength Data and
methods,testingmodes(force,displacement,orstraincontrol), Estimating Weibull Distribution Parameters forAdvanced
testing rates (force rate, stress rate, displacement rate, or strain Ceramics
rate), allowable bending, and data collection and reporting C1322Practice for Fractography and Characterization of
procedures are addressed. Note that tensile strength as used in Fracture Origins in Advanced Ceramics
this test method refers to the tensile strength obtained under D3379TestMethodforTensileStrengthandYoung’sModu-
uniaxial loading. lus for High-Modulus Single-Filament Materials
E4Practices for Force Verification of Testing Machines
1.2 Thistestmethodappliesprimarilytoadvancedceramics
E6Terminology Relating to Methods of MechanicalTesting
that macroscopically exhibit isotropic, homogeneous, continu-
E83Practice for Verification and Classification of Exten-
ous behavior. While this test method applies primarily to
someter Systems
monolithic advanced ceramics, certain whisker- or particle-
E337Test Method for Measuring Humidity with a Psy-
reinforcedcompositeceramicsaswellascertaindiscontinuous
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
fiber-reinforced composite ceramics may also meet these
peratures)
macroscopicbehaviorassumptions.Generally,continuousfiber
E1012Practice for Verification of Testing Frame and Speci-
ceramic composites (CFCCs) do not macroscopically exhibit
men Alignment Under Tensile and Compressive Axial
isotropic, homogeneous, continuous behavior and application
Force Application
of this practice to these materials is not recommended.
SI10-02IEEE/ASTMSI10 AmericanNationalStandardfor
1.3 Values expressed in this test method are in accordance
UseoftheInternationalSystemofUnits(SI):TheModern
with the International System of Units (SI) and SI10-02
Metric System
IEEE/ASTM SI 10 .
3. Terminology
1.4 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 The definitions of terms relating to tensile testing
responsibility of the user of this standard to establish appro-
appearing in Terminology E6 apply to the terms used in this
priate safety and health practices and determine the applica-
test method on tensile testing.The definitions of terms relating
bility of regulatory limitations prior to use. Specific precau-
to advanced ceramics testing appearing inTerminology C1145
tionary statements are given in Section 7.
applytothetermsusedinthistestmethod.Pertinentdefinitions
as listed in Practice C1239, Practice E1012, Terminology
C1145, and Terminology E6 are shown in the following with
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2010. Published December 2010. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1994. Last previous edition approved in 2005 as C1273–05. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1273-05R10.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1273 − 05 (2010)
the appropriate source given in parentheses. Additional terms vided in this test method. Note that size-scaling effects as
used in conjunction with this test method are defined in the discussed in Practice C1239 will affect the strength values.
following: Therefore, strengths obtained using different recommended
3.1.2 advanced ceramic—a highly engineered, high perfor- tensile test specimens with different volumes or surface areas
mance predominately nonmetallic, inorganic, ceramic material of material in the gage sections will be different due to these
having specific functional attributes. C1145 size differences. Resulting strength values can be scaled to an
effective volume or surface area of unity as discussed in
3.1.3 axial strain—the average of longitudinal strains mea-
Practice C1239.
sured at the surface on opposite sides of the longitudinal axis
of symmetry of the specimen by two strain-sensing devices
4.4 Tensile tests provide information on the strength and
located at the mid length of the reduced section. E1012
deformation of materials under uniaxial tensile stresses. Uni-
form stress states are required to effectively evaluate any
3.1.4 bending strain—the difference between the strain at
non-linear stress-strain behavior which may develop as the
the surface and the axial strain. In general, the bending strain
result of testing mode, testing rate, processing or alloying
variesfrompointtopointaroundandalongthereducedsection
effects, or environmental influences. These effects may be
of the specimen. E1012
consequences of stress corrosion or subcritical (slow) crack
3.1.5 breaking force—theforceatwhichfractureoccurs. E6
growth which can be minimized by testing at appropriately
3.1.6 fractography—means and methods for characterizing
rapid rates as outlined in this test method.
a fractured specimen or component. C1145
4.5 The results of tensile tests of test specimens fabricated
3.1.7 fracture origin—thesourcefromwhichbrittlefracture
to standardized dimensions from a particular material or
commences. C1145
selected portions, or both, of a part may not totally represent
3.1.8 percent bending—thebendingstraintimes100divided
the strength and deformation properties of the entire, full-size
by the axial strain. E1012
end product or its in-service behavior in different environ-
ments.
3.1.9 slow crack growth (SCG)—subcritical crack growth
(extension)whichmayresultfrom,butisnotrestrictedto,such
4.6 For quality control purposes, results derived from stan-
mechanisms as environmentally-assisted stress corrosion or
dardized tensile test specimens can be considered to be
diffusive crack growth. C1145
indicativeoftheresponseofthematerialfromwhichtheywere
3.1.10 tensile strength,—S —the maximum tensile stress taken for given primary processing conditions and post-
u
processing heat treatments.
which a material is capable of sustaining. Tensile strength is
calculated from the maximum force during a tension test
4.7 The tensile strength of a ceramic material is dependent
carried to rupture and the original cross-sectional area of the
on both its inherent resistance to fracture and the presence of
specimen. E6
flaws. Analysis of fracture surfaces and fractography, though
beyond the scope of this test method, is highly recommended
4. Significance and Use
for all purposes, especially for design data.
4.1 Thistestmethodmaybeusedformaterialdevelopment,
material comparison, quality assurance, characterization, and 5. Interferences
design data generation.
5.1 Test environment (vacuum, inert gas, ambient air, etc.)
4.2 High strength, monolithic advanced ceramic materials including moisture content (for example, relative humidity)
generallycharacterizedbysmallgrainsizes(<50µm)andbulk may have an influence on the measured tensile strength. In
densities near the theoretical density are candidates for load- particular, the behavior of materials susceptible to slow crack
bearing structural applications requiring high degrees of wear growthfracturewillbestronglyinfluencedbytestenvironment
and corrosion resistance, and high temperature strength. Al- and testing rate. Testing to evaluate the maximum strength
though flexural test methods are commonly used to evaluate potential of a material should be conducted in inert environ-
strength of advanced ceramics, the non-uniform stress distri- ments or at sufficiently rapid testing rates, or both, so as to
bution of the flexure test specimen limits the volume of minimizeslowcrackgrowtheffects.Conversely,testingcanbe
material subjected to the maximum applied stress at fracture. conducted in environments and testing modes and rates repre-
Uniaxially-loaded tensile strength tests provide information on sentative of service conditions to evaluate material perfor-
strength-limiting flaws from a greater volume of uniformly mance under use conditions. When testing is conducted in
stressed material. uncontrolled ambient air with the intent of evaluating maxi-
mum strength potential, relative humidity and temperature
4.3 Although the volume or surface area of material sub-
must be monitored and reported. Testing at humidity levels
jected to a uniform tensile stress for a single uniaxially-loaded
>65% relative humidity (RH) is not recommended and any
tensile test may be several times that of a single flexure test
deviations from this recommendation must be reported.
specimen, the need to test a statistically significant number of
tensiletestspecimensisnotobviated.Therefore,becauseofthe 5.2 Surface preparation of test specimens can introduce
probabilistic strength distributions of brittle materials such as fabrication flaws that may have pronounced effects on tensile
advanced ceramics, a sufficient number of test specimens at strength. Machining damage introduced during test specimen
each testing condition is required for statistical analysis and preparation can be either a random interfering factor in the
eventual design, with guidelines for sufficient numbers pro- determination of ultimate strength of pristine material (that is,
C1273 − 05 (2010)
increase frequency of surface initiated fractures compared to
volume initiated fractures), or an inherent part of the strength
characteristics to be measured. Surface preparation can also
lead to the introduction of residual stresses. Universal or
standardizedtestmethodsofsurfacepreparationdonotexist.It
should be understood that final machining steps may or may
not negate machining damage introduced during the early
coarse or intermediate machining. Thus, test specimen fabri-
cation history may play an important role in the measured
strength distributions and should be reported.
5.3 Bending in uniaxial tensile tests can cause or promote
non-uniformstressdistributionswithmaximumstressesoccur-
ring at the test specimen surface leading to non-representative
fracturesoriginatingatsurfacesorneargeometricaltransitions.
In addition, if strains or deformations are measured at surfaces
where maximum or minimum stresses occur, bending may
introduce over or under measurement of strains. Similarly,
fracturefromsurfaceflawsmaybeaccentuatedormutedbythe
FIG. 2 Example of a Smooth, Split Collet Active Gripping System
presence of the non-uniform stresses caused by bending.
for Cylindrical Test Specimens
6. Apparatus
6.1 Testing Machines—Machines used for tensile testing
6.2.1 General—Various types of gripping devices may be
shall conform to the requirements of Practices E4. The forces
used to transmit the measured force applied by the testing
used in determining tensile strength shall be accurate within
machine to the test specimens. The brittle nature of advanced
61%atanyforcewithintheselectedforcerangeofthetesting
ceramics requires a uniform interface between the grip com-
machine as defined in Practices E4. A schematic showing
ponents and the gripped section of the test specimen. Line or
pertinent features of the tensile testing apparatus is shown in
pointcontactsandnon-uniformpressurecanproduceHertizan-
Fig. 1.
type stresses leading to crack initiation and fracture of the test
6.2 Gripping Devices: specimen in the gripped section. Gripping devices can be
classed generally as those employing active and those employ-
ing passive grip interfaces as discussed in the following
sections.
6.2.2 Active Grip Interfaces—Active grip interfaces require
a continuous application of a mechanical, hydraulic, or pneu-
matic force to transmit the force applied by the test machine to
the test specimen. Generally, these types of grip interfaces
causeaforcetobeappliednormaltothesurfaceofthegripped
sectionofthetestspecimen.Transmissionoftheuniaxialforce
applied by the test machine is then accomplished by friction
between the test specimen and the grip faces. Thus, important
aspects of active grip interfaces are uniform contact between
the gripped section of the test specimen and the grip faces and
constant coefficient of friction over the grip/specimen inter-
face.
6.2.2.1 For cylindrical test specimens, a one-piece split-
collet arrangement acts as the grip interface (1, 2) as illus-
trated in Fig. 2. Generally, close tolerances are required for
concentricity of both the grip and test specimen diameters. In
addition, the diameter of the gripped section of the test
specimen and the unclamped, open diameter of the grip faces
must be within similarly close tolerances to promote uniform
contactatthetestspecimen/gripinterface.Toleranceswillvary
depending on the exact configuration as shown in the appro-
priate test specimen drawings.
FIG. 1 Schematic Diagram of One Possible Apparatus for Con- The boldface numbers given in parentheses refer to a list of references at the
ducting a Uniaxially-Loaded Tensile Test end of the text.
C1273 − 05 (2010)
6.2.2.2 For flat test specimens, flat-face, wedge-grip faces 6.3 Load Train Couplers:
actasthegripinterfaceasillustratedinFig.3.Generally,close
6.3.1 General—Various types of devices (load train cou-
tolerances are required for the flatness and parallelism as well
plers)maybeusedtoattachtheactiveorpassivegripinterface
as wedge angle of the grip faces. In addition, the thickness,
assemblies to the testing machine. The load train couplers in
flatness, and parallelism of the gripped section of the test
conjunction with the type of gripping devi
...
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