1、Designation: C1424 10Standard Test Method forMonotonic Compressive Strength of Advanced Ceramics atAmbient Temperature1This standard is issued under the fixed designation C1424; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of compres-sive strength including stress-strain behavior, under mono
3、tonicuniaxial loading of advanced ceramics at ambient temperature.This test method is restricted to specific test specimen geom-etries. In addition, test specimen fabrication methods, testingmodes (load or displacement), testing rates (load rate, stressrate, displacement rate, or strain rate), allow
4、able bending, anddata collection and reporting procedures are addressed. Com-pressive strength as used in this test method refers to thecompressive strength obtained under monotonic uniaxial load-ing. Monotonic loading refers to a test conducted at a constantrate in a continuous fashion, with no rev
5、ersals from testinitiation to final fracture.1.2 This test method is intended primarily for use withadvanced ceramics that macroscopically exhibit isotropic,homogeneous, continuous behavior. While this test method isintended for use on monolithic advanced ceramics, certainwhisker- or particle-reinfo
6、rced composite ceramics as well ascertain discontinuous fiber-reinforced composite ceramics mayalso meet these macroscopic behavior assumptions. Generally,continuous fiber ceramic composites (CFCCs) do not macro-scopically exhibit isotropic, homogeneous, continuous behav-ior and, application of this
7、 test method to these materials is notrecommended.1.3 Values expressed in this test method are in accordancewith the International System of Units (SI) and IEEE/ASTM SI10.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
8、 of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C773 Test Method for Compressive (Crushing) Strength ofFired Whiteware MaterialsC1145 Terminology of
9、Advanced CeramicsD695 Test Method for Compressive Properties of RigidPlasticsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of MechanicalTestingE83 Practice for Verification and Classification of Exten-someter SystemsE337 Test Method for Measuring Humidity
10、with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E1012 Practice for Verification of Test Frame and SpecimenAlignment Under Tensile and Compressive Axial ForceApplicationIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI) (The Modern Metric System3. Termi
11、nology3.1 DefinitionsThe definitions of terms relating to com-pressive testing appearing in Terminology E6, Test MethodD695, and Terminology C1145 may apply to the terms used inthis test method. Pertinent definitions as listed in PracticeE1012, Terminology C1145, and Terminology E6 are shown inthe f
12、ollowing with the appropriate source given in parentheses.Additional terms used in conjunction with this test method aredefined in the following.3.1.1 advanced ceramic, na highly engineered, high-performance predominately nonmetallic, inorganic, ceramicmaterial having specific functional attributes.
13、 (C1145)3.1.2 axial strain, n L/Lthe average longitudinal strainsmeasured at the surface on opposite sides of the longitudinalaxis of symmetry of the specimen by two strain-sensing1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility o
14、f Subcommittee C28.01 onMechanical Properties and Performance.Current edition approved Dec. 1, 2010. Published January 2011. Originallypublished in 1999. Last previous edition approved in 2004 as C1424 04. DOI:10.1520/C1424-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orc
15、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.devices located at
16、the mid length of the reduced section.(E1012)3.1.3 bending strain, n L/Lthe difference between thestrain at the surface and the axial strain. In general, the bendingstrain varies from point to point around and along the reducedsection of the test specimen. (E1012)3.1.4 breaking load, n Fthe load at
17、which fractureoccurs. (E6)3.1.5 compressive strength, n F/L2the maximum com-pressive stress which a material is capable of sustaining.Compressive strength is calculated from the maximum loadduring a compression test carried to rupture and the originalcross-sectional area of the specimen. (E6)3.1.6 g
18、age length, n Lthe original length of that portionof the specimen over which strain or change of length isdetermined. (E6)3.1.7 modulus of elasticity, n F/L2the ratio of stress tocorresponding strain below the proportional limit. (E6)3.1.8 percent bending, nthe bending strain times 100divided by the
19、 axial strain. (E1012)4. Significance and Use4.1 This test method may be used for material development,material comparison, quality assurance, characterization, anddesign data generation.4.2 Generally, resistance to compression is the measure ofthe greatest strength of a monolithic advanced ceramic.
20、 Ideally,ceramics should be compressively stressed in use, althoughengineering applications may frequently introduce tensilestresses in the component. Nonetheless, compressive behavioris an important aspect of mechanical properties and perfor-mance. Although tensile strength distributions of ceramic
21、s areprobabilistic and can be described by a weakest link failuretheory, such descriptions have been shown to be inapplicable tocompressive strength distributions in at least one study (1).3However, the need to test a statistically significant number ofcompressive test specimens is not obviated. The
22、refore, asufficient number of test specimens at each testing condition isrequired for statistical analysis and design.4.3 Compression tests provide information on the strengthand deformation of materials under uniaxial compressivestresses. Uniform stress states are required to effectivelyevaluate an
23、y nonlinear stress-strain behavior which may de-velop as the result of cumulative damage processes (forexample, microcracking) which may be influenced by testingmode, testing rate, processing or compositional effects, micro-structure, or environmental influences.4.4 The results of compression tests
24、of test specimensfabricated to standardized dimensions from a particular mate-rial or selected portions of a part, or both, may not totallyrepresent the strength and deformation properties in the entire,full-size product or its in-service behavior in different environ-ments.4.5 For quality control p
25、urposes, results derived from stan-dardized compressive test specimens may be considered in-dicative of the response of the material from which they weretaken for given primary processing conditions and post-processing heat treatments.5. Interferences5.1 Test environment (vacuum, inert gas, ambient
26、air, and soforth) including moisture content (for example, relative humid-ity) may have an influence on the measured compressivestrength. Testing to evaluate the maximum strength potential ofa material can be conducted in inert environments or atsufficiently rapid testing rates, or both, so as to mi
27、nimize anyenvironmental effects. Conversely, testing can be conducted inenvironments, test modes, and test rates representative ofservice conditions to evaluate material performance under useconditions. When testing is conducted in uncontrolled ambientair with the intent of evaluating maximum streng
28、th potential,relative humidity and temperature must be monitored andreported.5.2 Fabrication of test specimens can introduce dimensionalvariations which may have pronounced effects on compressivemechanical properties and behavior (for example, shape andlevel of the resulting stress-strain curve, com
29、pressive strength,induced bending, and so forth). Machining effects introducedduring test specimen preparation can be an interfering factor inthe determination of ultimate strength of pristine material (thatis, increased frequency of loading block related fractures (seeFig. 1) compared to volume-ini
30、tiated fractures). Surface prepa-ration can also lead to the introduction of residual stresses.Universal or standardized test methods of surface preparationdo not exist. It should be understood that final machining stepsmay or may not negate machining damage introduced duringthe initial machining. N
31、ote that final compressive fracture ofadvanced ceramics can be attributed to the interaction of largenumbers of microcracks that are generated in the volume of thematerial and ultimately lead to loss of structural integrity. (1,2).Therefore, although surface roughness in the gage section ofthe test
32、specimen is not as critical for determining maximumstrength potential as it is for flexure or tension tests ofadvanced ceramics, test specimen fabrication history may play3The boldface numbers in parenthesis refer to the list of references at the end ofthis test methodFIG. 1 Schematic Diagram of One
33、 Possible Apparatus forConducting a Uniaxially Loaded Compression TestC1424 102an important role in the measured compressive strength distri-butions and should be reported. In addition, the nature offabrication used for certain advanced ceramics (for example,pressureless sintering, hot pressing) may
34、 require the testing oftest specimens with gage sections in the as-processed condition(that is, it may not be possible or desired/required to machinesome test specimen surfaces not directly in contact with testfixture components). For very rough or wavy as-processedsurfaces eccentricities in the str
35、ess state due to nonsymmetriccross sections as well as variation in the cross-sectionaldimensions may also interfere with the compressive strengthmeasurement. Finally, close geometric tolerances, particularlyin regard to flatness, concentricity, and cylindricity of testspecimen surfaces or geometric
36、 entities in contact with the testfixture components) are critical requirements for successfulcompression tests.5.3 Bending in uniaxial compression tests can introduceeccentricity leading to geometric instability of the test speci-men and buckling failure before valid compressive strength isattained
37、. In addition, if deformations or strains are measured atsurfaces where maximum or minimum stresses occur, bendingmay introduce over or under measurement of strains dependingon the location of the strain-measuring device on the testspecimen.5.4 Fractures that initiate outside the uniformly stressedg
38、age section or splitting of the test specimen along itslongitudinal centerline may be due to factors such as stressconcentrations or geometrical transitions, extraneous stressesintroduced by the load fixtures, misalignment of the testspecimen/loading blocks, nonflat loading blocks or nonflat testspe
39、cimen ends, or both, or strength-limiting features in themicrostructure of the test specimen. Such non-gage sectionfractures will normally constitute invalid tests.6. Apparatus6.1 Testing MachinesMachines used for compression test-ing shall conform to the requirements of Practices E4. Theforces used
40、 in determining compressive strength shall beaccurate within 61 % at any force within the selected forcerange of the testing machine as defined in Practices E4.Aschematic showing pertinent features of one possible compres-sive testing apparatus is shown in Fig. 1. Check that theexpected breaking for
41、ce for the desired test specimen geometryand test material is within the capacity of the test machine andforce transducer. Advanced ceramic compression test speci-mens require much greater forces to fracture than those usuallyencountered in tension or flexure test specimens of the samematerial.6.2 L
42、oading Fixtures:6.2.1 GeneralCompression loading fixtures are generallycomposed of two parts: (1) basic steel compression fixtures (forexample, platens) attached to the test machine and (2) loadingblocks which are non-fixed and act as the interface between thecompression platens and the test specime
43、n. An assemblydrawing of such a fixture and a test specimen is shown in Fig.2. The brittle nature of advanced ceramics requires a uniforminterface between the loading fixtures and the test specimen.Line or point contact stresses lead to crack initiation andfracture of the test specimen at stresses l
44、ess than the actualcompressive strength (that is, where actual strength is theintrinsic strength of the material not influenced by the test ortest conditions). In addition, large mismatches of Poissonsratios or elastic moduli between the loading fixture and testspecimen, or both, can introduce later
45、al tensile forces leadingto splitting of the compression test specimen. Similarly, plasticdeformation of the load fixture can induce lateral tensile forceswith the same effect.6.2.1.1 Hardened (48 HRc) steel compression platens shallbe greater in diameter ($25.4 mm) than the loading blocks andshall
46、be at least 25.4 mm in thickness. The loading surfaces ofthe compression platens shall be flat to 0.005 mm. In addition,the two loading surfaces (loading face used to contact theloading blocks and bolted face used to attach the platen to thetest machine) shall be parallel to 0.005 mm. When installed
47、 inthe test machine, the loading surfaces of the upper and lowercompression platens shall be parallel to each other within 0.01mm and perpendicular to the load line of the test machine towithin 0.01 mm (2). The upper and lower compression platensshall be concentric within 0.005 mm of each other and
48、the loadline of the test machine. Angular and concentricity alignmentshave been achieved with commercial alignment devices or byusing available hole tolerances in commercial compressionplatens in conjunction with shims (2).6.2.1.2 Loading blocks as shown in Fig. 3 shall have thesame diameter as the
49、test specimen ends at their interface.Parallelism and flatness of faces as well as concentricity of theloading blocks shall be as given in Fig. 3. The material for theFIG. 2 Example of Basic Fixturing and Test Specimen forCompression TestingC1424 103loading blocks shall be chosen to meet the following require-ments. Generally, cobalt-sintered tungsten carbide (Co-WC)has worked satisfactorily for this purpose in compression testsof a variety of advanced ceramics (2). However, for somehigh-performance advanced ceramics, other loading blockmaterials may be req
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