1、Designation: C1337 17Standard 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 us
7、er 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 Monotoni
8、c 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 Mechanical TestingE83 Pra
9、ctice for Verification and Classification of Exten-someter SystemsE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE337 Test Method for Measuring Humidity with a Psy-chrometer (th
10、e 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/ASTM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Termino
11、logy3.1 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 advanced ceramicsappearing in Terminology C1145 apply to the terms used in thistest method. The definitions of terms relat
12、ing to fiber rein-forced composites appearing in Terminology D3878 apply to1This 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 Feb. 1, 2017. Published Februa
13、ry 2017. Originallyapproved in 1996. Last previous edition approved in 2015 as C1337 10 (2015).DOI: 10.1520/C1337-17.2For 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
14、 the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established i
15、n the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1Mon Apr 30 18 the terms used in this test method. Additional terms used inconjunction with this test method are d
16、efined in the following:3.1.2 ceramic matrix compositematerial consisting of twoor more materials (insoluble in one another), in which themajor, continuous component (matrix component) is a ceramic,while the secondary component/s (reinforcing component) maybe ceramic, glass-ceramic, glass, metal, or
17、 organic in nature.These components are combined on a macroscale to form auseful engineering material possessing certain properties orbehavior not possessed by the individual constituents. C11453.1.3 continuous fiber-reinforced ceramic matrix composite(CFCC)ceramic matrix composite in which the rein
18、forcingphase consists of a continuous fiber, continuous yarn, or awoven fabric.3.1.4 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
19、-sectional area of thetest specimen.3.1.4.1 DiscussionIn some cases, the fracture strengthmay 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.3.1.5 proportio
20、nal limit stressgreatest stress which a ma-terial is capable of sustaining without any deviation fromproportionality of stress to strain (Hookes law).3.1.5.1 DiscussionMany experiments have shown thatvalues observed for the proportional limit vary greatly with thesensitivity and accuracy of the test
21、 equipment, eccentricity ofloading, the scale to which the stress-strain diagram is plotted,and other factors. When determination of proportional limit isrequired, the procedure and sensitivity of the test equipmentshall be specified.3.1.6 slow crack growthsubcritical crack growth (exten-sion) which
22、 may result from, but is not restricted to, suchmechanisms as environmentally assisted stress corrosion ordiffusive crack growth. C11454. Significance and Use4.1 This test method may be used for material development,material comparison, quality assurance, characterization, anddesign data generation.
23、4.2 Continuous fiber-reinforced ceramic matrix compositesare candidate materials for structural 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 tem
24、perature. Creeprupture tests provide a measure of the life of the material whensubjected 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 c
25、apability which best defines theservice usefulness of the material.4.4 Creep and creep rupture 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 effec
26、tivelyevaluate any nonlinear stress-strain behavior which may de-velop as the result of cumulative damage processes (forexample, matrix cracking, matrix/fiber debonding, fiberfracture, delamination, etc.) which may be influenced by testmode, test rate, processing or alloying effects, environmentalin
27、fluences, or elevated temperatures. Some of these effects maybe consequences of stress corrosion or subcritical (slow) crackgrowth. It is noted that ceramic materials typically creep morerapidly in tension than in compression. Therefore, creep datafor design and life prediction should be obtained in
28、 bothtension and compression.4.5 The results of tensile creep and tensile creep 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,
29、 full-size end product or its in-servicebehavior in different environments or at 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 pr
30、imary processing conditions and post-processing heattreatments.5. Interferences5.1 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 m
31、aterials susceptibleto slow crack growth fracture and oxidation will be stronglyinfluenced 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 sp
32、ecimens, although nor-mally not considered a major concern with CFCCs, canintroduce 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 spe
33、cimen preparationcan be either a random interfering factor in the ultimatestrength of pristine material (that is, increased frequency ofsurface-initiated fractures compared to volume-initiated frac-tures) or an inherent part of the strength characteristics to bemeasured. Surface preparation can also
34、 lead to the introductionof residual stresses. Universal or standardized test methods 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 a
35、n important role in themeasured time-to-failure or deformation, and shall be reported.In addition, the nature of fabrication used for certain compos-ites (for example, chemical vapor infiltration or hot pressing)C1337 172Mon Apr 30 18 may require the testing of specimens in the as-processedcondition
36、 (that is, it may not be possible to machine the testspecimen faces without compromising the in-plane fiber archi-tecture).5.3 Bending in uniaxial tests does induce nonuniform stressdistributions. Bending may be introduced from several sourcesincluding misaligned load trains, eccentric or misshapeds
37、pecimens, and nonuniformly heated specimens or grips. Inaddition, if deformations or strains 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. Simil
38、arly, fracture from surface flaws may be accentuatedor suppressed by the presence of the 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
39、 stressesintroduced by gripping or thermal gradients, or strength limit-ing features in 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 init
40、iation of fracture.Insufficient pressure can shear the outer plies in laminatedCFCCs, while 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 constitu
41、ents makes itnecessary that the precise loading history of a creep testspecimen be specified. 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
42、end ofloading will depend on the magnitude of the test rate, the teststress, the test temperature and the relative creep resistance ofthe 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 specimen
43、accumulated time-dependent deformation, the specimen mayexhibit creep recovery as manifested 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
44、 them quite sensitive to temperature. Often it is desiredto determine the retained strength 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 thesec
45、ircumstances, the time elapsed between the end of the creeptest and the conduction of 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.
46、Apparatus6.1 Test MachinesMachines used for tensile testing shallconform to the requirements of Practices E4. The forces usedshall be accurate within 61 % at any force within the selectedforce range of the test machine as defined in Practices E4.6.2 Gripping Devices:6.2.1 GeneralVarious types of gri
47、pping devices may beused to transmit the measured force applied by the test machineto the test specimens. The brittle nature of the matrices ofCFCCs requires that a uniform interface exists between thegrip components and the gripped section of the specimen. Lineor point contacts and nonuniform press
48、ure can produceHertzian-type stresses leading to crack initiation and fracture ofthe test specimen in the gripped section. Gripping devices canbe classified generally as those employing active and thoseemploying passive grip interfaces as discussed in the followingsections. Grips located outside the
49、 heated zone surrounding thespecimen may or may not employ cooling. Uncooled gripslocated outside the heated zone are termed “warm” grips andgenerally reduce the thermal gradient in the test specimen butat the expense of using high-temperature alloy grips andincreased degradation of the grips due to exposure to theelevated-temperature environment. Cooled grips located out-side the heated zone are termed “cold” grips and generallyinduce a steep thermal gradient along the length of thespecimen.NOTE 1The expense of the cooling system for cold grips is balancedagain
