1、Designation: C1337 10 (Reapproved 2015)Standard Test Method forCreep and Creep Rupture of Continuous Fiber-ReinforcedAdvanced Ceramics Under Tensile Loading at ElevatedTemperatures1This standard is issued under the fixed designation C1337; the number immediately following the designation indicates t
2、he year oforiginal adoption or, in the case of revision, the year 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 the
3、time-dependent deformation and time-to-rupture of continuousfiber-reinforced ceramic composites under constant tensileloading at elevated temperatures. This test method addresses,but is not restricted to, various suggested test specimengeometries. In addition, test specimen fabrication methods,allow
4、able bending, temperature measurements, temperaturecontrol, data collection, and reporting procedures are ad-dressed.1.2 This test method is intended primarily for use with alladvanced ceramic matrix composites with continuous fiberreinforcement: unidirectional (1-D), bidirectional (2-D), andtridire
5、ctional (3-D). In addition, this test method may also beused with glass matrix composites with 1-D, 2-D, and 3-Dcontinuous fiber reinforcement. This test method does notaddress directly discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics, although the testmethods d
6、etailed here may be equally applicable to thesecomposites.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 therespo
7、nsibility 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. Hazard statementsare noted in 7.1 and 7.2.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1275 Test
8、Method for Monotonic Tensile Behavior ofContinuous Fiber-Reinforced Advanced Ceramics withSolid Rectangular Cross-Section Test Specimens at Am-bient TemperatureD3878 Terminology for Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechan
9、ical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE139 Test Methods for Conducting Creep, Creep-Rupture,and Stress-Rupture Tests of Metallic MaterialsE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE230 Specification and Temperature-Electro
10、motive Force(EMF) Tables for Standardized ThermocouplesE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationIEEE/AS
11、TM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminology3.1 Definitions:3.1.1 The definitions of terms relating to tensile testingappearing in Terminology E6 apply to the terms used in thistest method. The definitions relating to adv
12、anced ceramics1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Composites.Current edition approved July 1, 2015. Published September 2015. Originallyapproved in 1996. Last previous edition a
13、pproved in 2010 as C1337 10. DOI:10.1520/C1337-10R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyrigh
14、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1appearing in Terminology C1145 apply to the terms used in thistest method. The definitions of terms relating to fiber rein-forced composites appearing in Terminology D3878 apply tothe terms used
15、 in this test method. Additional terms used inconjunction with this test method are defined in the following:3.1.2 continuous fiber-reinforced ceramic matrix composite(CFCC)ceramic matrix composite in which the reinforcingphase consists of a continuous fiber, continuous yarn, or awoven fabric.3.1.3
16、fracture strength (F/L2)tensile stress that the mate-rial sustains at the instant of fracture. Fracture strength iscalculated from the force at fracture during a tension testcarried to rupture and the original cross-sectional area of thetest specimen.3.1.3.1 DiscussionIn some cases, the fracture str
17、engthmay be identical to the tensile strength if the load at fracture isthe maximum for the test. Factors such as load train compli-ance and fiber pull-out behavior may influence the fracturestrength.3.1.4 proportional limit stressgreatest stress which a ma-terial is capable of sustaining without an
18、y deviation fromproportionality of stress to strain (Hookes law).3.1.4.1 DiscussionMany experiments have shown thatvalues observed for the proportional limit vary greatly with thesensitivity and accuracy of the testing equipment, eccentricityof loading, the scale to which the stress-strain diagram i
19、splotted, and other factors. When determination of proportionallimit is required, the procedure and sensitivity of the testequipment shall be specified.3.1.5 slow crack growthsubcritical crack growth (exten-sion) which may result from, but is not restricted to, suchmechanisms as environmentally assi
20、sted stress corrosion ordiffusive crack growth.4. Significance and Use4.1 This test method may be used for material development,material comparison, quality assurance, characterization, anddesign data generation.4.2 Continuous fiber-reinforced ceramic matrix compositesare candidate materials for str
21、uctural applications requiringhigh degrees of wear and corrosion resistance and toughness athigh temperatures.4.3 Creep tests measure the time-dependent deformation ofa material under constant load at a given temperature. Creeprupture tests provide a measure of the life of the material whensubjected
22、 to constant mechanical loading at elevated tempera-tures. In selecting materials and designing parts for service atelevated temperatures, the type of test data used will depend onthe criteria for load-carrying capability which best defines theservice usefulness of the material.4.4 Creep and creep r
23、upture tests provide information on thetime-dependent deformation and on the time-of-failure ofmaterials subjected to uniaxial tensile stresses at elevatedtemperatures. Uniform stress states are required to effectivelyevaluate any nonlinear stress-strain behavior which may de-velop as the result of
24、cumulative damage processes (forexample, matrix cracking, matrix/fiber debonding, fiberfracture, delamination, etc.) which may be influenced bytesting mode, testing rate, processing or alloying effects,environmental influences, or elevated temperatures. Some ofthese effects may be consequences of st
25、ress corrosion orsubcritical (slow) crack growth. It is noted that ceramicmaterials typically creep more rapidly in tension than incompression. Therefore, creep data for design and life predic-tion should be obtained in both tension and compression.4.5 The results of tensile creep and tensile creep
26、rupturetests of specimens fabricated to standardized dimensions froma particular material or selected portions of a part, or both, maynot totally represent the creep deformation and creep ruptureproperties of the entire, full-size end product or its in-servicebehavior in different environments or at
27、 various elevatedtemperatures.4.6 For quality control purposes, results derived from stan-dardized tensile test specimens may be considered indicative ofthe response of the material from which they were taken forgiven primary processing conditions and post-processing heattreatments.5. Interferences5
28、.1 Test environment (vacuum, inert gas, ambient air, etc.)including moisture content (for example, relative humidity)may have an influence on the creep and creep rupture behaviorof CFCCs. In particular, the behavior of materials susceptibleto slow crack growth fracture and oxidation will be strongly
29、influenced by test environment and test temperature. Testingcan be conducted in environments representative of serviceconditions to evaluate material performance under these con-ditions.5.2 Surface preparation of test specimens, although nor-mally not considered a major concern with CFCCs, canintrod
30、uce fabrication flaws which may have pronounced effectson the mechanical properties and behavior (for example, shapeand level of the resulting stress-strain-time curve, etc.). Ma-chining damage introduced during test specimen preparationcan be either a random interfering factor in the ultimatestreng
31、th of pristine material (that is, increased frequency ofsurface-initiated fractures compared to volumeinitiated frac-tures) or an inherent part of the strength characteristics to bemeasured. Surface preparation can also lead to the introductionof residual stresses. Universal or standardized test met
32、hods ofsurface preparation do not exist. It should be understood thatfinal machining steps may or may not negate machiningdamage introduced during the initial machining. Thus, testspecimen fabrication history may play an important role in themeasured time-to-failure or deformation, and shall be repo
33、rted.In addition, the nature of fabrication used for certain compos-ites (for example, chemical vapor infiltration or hot pressing)may require the testing of specimens in the as-processedcondition (that is, it may not be possible to machine the testspecimen faces without compromising the in-plane fi
34、ber archi-tecture).5.3 Bending in uniaxial tests does induce nonuniform stressdistributions. Bending may be introduced from several sourcesincluding misaligned load trains, eccentric or misshapedC1337 10 (2015)2specimens, and nonuniformly heated specimens or grips. Inaddition, if deformations or str
35、ains are measured at surfaceswhere maximum or minimum stresses occur, bending mayintroduce over or under measurement of strains depending onthe location of the strain measuring device on the test speci-men. Similarly, fracture from surface flaws may be accentuatedor suppressed by the presence of the
36、 nonuniform stressescaused by bending.5.4 Fractures that initiate outside the uniformly stressedgage section of a specimen may be due to factors such as stressconcentrations or geometrical transitions, extraneous stressesintroduced by gripping or thermal gradients, or strength limit-ing features in
37、the microstructure of the test specimen. Suchnon-gage section fractures will normally constitute invalidtests. In addition, for face-loaded test specimen geometries,gripping pressure is a key variable in the initiation of fracture.Insufficient pressure can shear the outer plies in laminatedCFCCs, wh
38、ile too much pressure can cause local crushing ofthe CFCC and lead to fracture in the vicinity of the grips.5.5 The time-dependent stress redistribution that occurs atelevated temperatures among the CFCC constituents makes itnecessary that the precise loading history of a creep testspecimen be speci
39、fied. This is of particular importance sincethe rate at which a creep load is initially applied can influencethe subsequent creep behavior and damage modes. Forexample, whether matrix cracking would occur at the end ofloading will depend on the magnitude of the loading rate, thetest stress, the test
40、 temperature and the relative creep resistanceof the matrix with respect to that of the fibers.3,45.6 When CFCCs are mechanically unloaded either partiallyor totally after a creep test during which the test specimenaccumulated time-dependent deformation, the specimen mayexhibit creep recovery as man
41、ifested by a time-dependentreduction of strain. The rate of creep recovery is usually slowerthan the rate of creep deformation, and both creep and creeprecovery are in most cases thermally activated processes,making them quite sensitive to temperature. Often it is desiredto determine the retained st
42、rength of a CFCC after beingsubjected to creep for a prescribed period of time. Therefore, itis customary to unload the test specimen from the creep stressand then reload it monotonically until failure. Under thesecircumstances, the time elapsed between the end of the creeptest and the conduction of
43、 the monotonic fast fracture test todetermine the retained strength as well as the loading andunloading rates will influence the rate of internal stressredistribution among the phases and hence the CFCC strength.6. Apparatus6.1 Testing MachinesMachines used for tensile testingshall conform to the re
44、quirements of Practices E4. The forcesused shall be accurate within 61 % at any force within theselected force range of the testing machine as defined inPractices E4.6.2 Gripping Devices:6.2.1 GeneralVarious types of gripping devices may beused to transmit the measured force applied by the testingma
45、chine to the test specimens. The brittle nature of thematrices of CFCCs requires that a uniform interface existsbetween the grip components and the gripped section of thespecimen. Line or point contacts and nonuniform pressure canproduce Hertzian-type stresses leading to crack initiation andfracture
46、 of the test specimen in the gripped section. Grippingdevices can be classified generally as those employing activeand those employing passive grip interfaces as discussed in thefollowing sections. Grips located outside the heated zonesurrounding the specimen may or may not employ cooling.Uncooled g
47、rips located outside the heated zone are termedwarm grips and generally reduce the thermal gradient in thetest specimen but at the expense of using high-temperaturealloy grips and increased degradation of the grips due toexposure to the elevated-temperature environment. Cooledgrips located outside t
48、he heated zone are termed cold grips andgenerally induce a steep thermal gradient along the length ofthe specimen.NOTE 1The expense of the cooling system for cold grips is balancedagainst maintaining alignment that remains consistent from test to test(stable grip temperature) and decreased degradati
49、on of the grips due toexposure to the elevated-temperature environment. When grip cooling isemployed, provisions shall be provided to control the cooling medium tomaximum fluctuations of 5 K (less than 1 K preferred) about a setpointtemperature over the course of the test to minimize thermally inducedstrain changes in the test specimen. In addition, opposing grip tempera-tures should be maintained at uniform and consistent temperatures not toexceed a difference 65 K (less than 61 K preferred) so as to avoidinducing unequal thermal gradients and subsequent nonuniaxial stres
