1、Designation: C1337 10Standard 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 the year oforiginal
2、 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 time-dependent def
3、ormation 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,allowable bending, temp
4、erature 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), andtridirectional (3-D). In
5、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 detailed here may b
6、e 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 theresponsibility of the u
7、ser 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 Method for Monoton
8、ic Tensile Behavior ofContinuous Fiber-Reinforced Advanced Ceramics withSolid Rectangular Cross-Section Test Specimens at Ambi-ent TemperatureD3878 Terminology for Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Pr
9、actice 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-Electromotive Force(EMF)
10、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 Test Frame and SpecimenAlignment Under Tensile and Compressive Axial ForceApplicationIEEE/ASTM SI 10 American Natio
11、nal Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminology3.1 DefinitionsThe definitions of terms relating to tensiletesting appearing in Terminology E6 apply to the terms used in1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ce
12、ramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Composites.Current edition approved Dec. 1, 2010. Published January 2011. Originallyapproved in 1996. Last previous edition approved in 2005 as C1337 96 (2005).DOI: 10.1520/C1337-10.2For referenced ASTM standards, visit
13、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
14、, United States.this test method. The definitions relating to advanced ceramicsappearing 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 in this test method. Addit
15、ional terms used inconjunction with this test method are defined in the following:3.1.1 continuous fiber-reinforced ceramic matrix composite(CFCC)ceramic matrix composite in which the reinforcingphase consists of a continuous fiber, continuous yarn, or awoven fabric.3.1.2 fracture strength (F/L2)ten
16、sile 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.3.1.2.1 DiscussionIn some cases, the fracture strengthmay be identical to th
17、e 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.3.1.3 proportional limit stressgreatest stress which a ma-terial is capable of sustaining without any deviation fromproportiona
18、lity of stress to strain (Hookes law).3.1.3.1 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 isplotted, and other factors
19、. When determination of proportionallimit is required, the procedure and sensitivity of the testequipment shall be specified.3.1.4 slow crack growthsubcritical crack growth (exten-sion) which may result from, but is not restricted to, suchmechanisms as environmentally assisted stress corrosion ordif
20、fusive 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 structural applications requir
21、inghigh 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 to constant mechanical loa
22、ding 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 rupture tests provide inform
23、ation 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 cumulative damage processes
24、 (forexample, matrix cracking, matrix/fiber debonding, fiber frac-ture, delamination, etc.) which may be influenced by testingmode, testing rate, processing or alloying effects, environmen-tal influences, or elevated temperatures. Some of these effectsmay be consequences of stress corrosion or subcr
25、itical (slow)crack growth. It is noted that ceramic materials typically creepmore rapidly in tension than in compression. Therefore, creepdata for design and life prediction should be obtained in bothtension and compression.4.5 The results of tensile creep and tensile creep rupturetests of specimens
26、 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 various elevatedtemperat
27、ures.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. Interferences5.1 Test environment (vacu
28、um, 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 stronglyinfluenced by test enviro
29、nment 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, canintroduce fabrication flaws whi
30、ch 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 ultimatestrength of pristine material (
31、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 methods ofsurface preparatio
32、n 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 reported.In addition, the nat
33、ure 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 fiber archi-tecture).5.3 Be
34、nding in uniaxial tests does induce nonuniform stressdistributions. Bending may be introduced from several sourcesincluding misaligned load trains, eccentric or misshaped speci-mens, and nonuniformly heated specimens or grips. In addi-tion, if deformations or strains are measured at surfaces wherema
35、ximum or minimum stresses occur, bending may introduceC1337 102over or under measurement of strains depending on thelocation of the strain measuring device on the test specimen.Similarly, fracture from surface flaws may be accentuated orsuppressed by the presence of the nonuniform stresses causedby
36、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 the microstructure of the test
37、 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, while too much pressure can caus
38、e 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 specified. This is of particular im
39、portance sincethe rate at which a creep load is initially applied can influencethe subsequent creep behavior and damage modes. For ex-ample, whether matrix cracking would occur at the end ofloading will depend on the magnitude of the loading rate, thetest stress, the test temperature and the relativ
40、e 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 manifested by a time-dependentr
41、eduction 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 strength of a CFCC after being
42、subjected 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 the monotonic fast fracture
43、 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 requirements of Practices E4.
44、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 testingmachine to the test specimens.
45、 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 of the test specimen in the
46、 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 grips located outside the hea
47、ted 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 the heated zone are termed co
48、ld 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 degradation of the grips due toexposu
49、re 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 stresses inthe specimen. General
