1、Designation: C 1425 05Standard Test Method forInterlaminar Shear Strength of 1D and 2D ContinuousFiber-Reinforced Advanced Ceramics at ElevatedTemperatures1This standard is issued under the fixed designation C 1425; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method addresses the compression of a double-notched specimen
3、to determine interlaminar shear strength ofcontinuous fiber-reinforced ceramic composites (CFCCs) atelevated temperatures. Specimen preparation methods andrequirements, testing modes (load or displacement control),testing rates (load rate or displacement rate), data collection,and reporting procedur
4、es are addressed.1.2 This test method is used for testing advanced ceramic orglass matrix composites with continuous fiber reinforcementhaving a laminated structure such as in unidirectional (1-D) orbidirectional (2-D) fiber architecture (lay-ups of unidirectionalplies or stacked fabric). This test
5、method does not addresscomposites with nonlaminated structures, such as (3-D) fiberarchitecture or discontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics.1.3 Values expressed in this test method are in accordancewith the International System of Units (SI) and IEEE/AST
6、MSI 10.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility 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. Specifi
7、c precau-tionary statements are noted in 8.1 and 8.2.2. Referenced Documents2.1 ASTM Standards:2C 1145 Terminology on Advanced CeramicsC 1292 Test Method for Shear Strength of ContinuousFiber-Reinforced Ceramics at Ambient TemperaturesD 695 Test Method for Compressive Properties of RigidPlasticsD 38
8、46 Test Method for In-Plane Shear Strength of Rein-forced PlasticsD 3878 Terminology for Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerabl
9、e Error, the Average for Charac-teristic of a Lot or ProcessE 220 Test Method for Calibration of Thermocouples byComparison TechniquesE 230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 337 Test Method for Measuring Humidity with a Psy-chrometer (the M
10、easurement of Wet-Bulb and Dry-BulbTemperatures)IEEE/ASTM SI 10 American National Standard for Use ofthe International System of Units (SI): The Modern MetricSystem3. Terminology3.1 DefinitionsThe definitions of terms relating to shearstrength testing appearing in Terminology E6 apply to theterms us
11、ed in this test method. The definitions of terms relatingto advanced ceramics appearing in Terminology C 1145 applyto the terms used in this test method. The definitions of termsrelating to fiber-reinforced composites appearing in Terminol-ogy D 3878 apply to the terms used in this test method.4. Su
12、mmary of Test Method4.1 This test method addresses the determination of theinterlaminar shear strength of CFCCs at elevated temperatures.The interlaminar shear strength of CFCCs, as determined bythis test method, is measured by loading in compression adouble-notched specimen of uniform width. Failur
13、e of thespecimen occurs by interlaminar shear between two centrallylocated notches machined halfway through the thickness of thespecimen and spaced a fixed distance apart on opposing faces.Schematics of the loading mode and the specimen are shown in1This test method is under the jurisdiction of ASTM
14、 Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Composites.Current edition approved Feb. 1, 2005. Published April 2005. Originallyapproved in 1999. Last previous edition approved in 1999 as C 1425 99.2For referenced ASTM standards, visit th
15、e 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,
16、United States.Fig. 1. The procedures in this test method are similar to thosein Test Method C 1292 for the determination of the interlami-nar shear strength of CFCCs at ambient temperature, exceptthat the considerations for conducting the test at elevatedtemperatures are addressed in this test metho
17、d.5. Significance and Use5.1 Continuous fiber-reinforced ceramic composites arecandidate materials for structural applications requiring highdegrees of wear and corrosion resistance, and damage toler-ance at high temperatures.5.2 The 1-D and 2-D CFCCs are highly anisotropic andtheir transthickness t
18、ensile and interlaminar shear strength arelower than their in-plane tensile and in-plane shear strength,respectively.5.3 Shear tests provide information on the strength anddeformation of materials under shear stresses.5.4 This test method may be used for material development,material comparison, qua
19、lity assurance, characterization, anddesign data generation.5.5 For quality control purposes, results derived from stan-dardized shear test specimens may be considered indicative ofthe response of the material from which they were taken forgiven primary processing conditions and post-processing heat
20、treatments.6. Interferences6.1 Test environment (vacuum, inert gas, ambient air, and soforth) including moisture content (for example, relative humid-ity) may have an influence on the measured interlaminar shearstrength. In particular, the behavior of materials susceptible toslow crack growth will b
21、e strongly influenced by test environ-ment and testing rate. Testing to evaluate the maximumstrength potential of a material shall be conducted in inertenvironments or at sufficiently rapid testing rates, or both, so asto minimize slow crack growth effects. Conversely, testing canbe conducted in env
22、ironments and testing modes and ratesrepresentative of service conditions to evaluate material per-formance under those conditions. When testing is conducted inuncontrolled ambient air with the objective of evaluatingmaximum strength potential, relative humidity and temperaturemust be monitored and
23、reported. Testing at humidity levels65 % RH is not recommended and any deviations from thisrecommendation must be reported.6.2 Preparation of test specimens, although normally notconsidered a major concern with CFCCs, can introduce fabri-cation flaws which may have pronounced effects on themechanica
24、l properties and behavior (for example, shape andlevel of the resulting load-displacement curve and shearstrength). Machining damage introduced during specimenpreparation can be either a random interfering factor in thedetermination of shear strength of pristine material, or aninherent part of the s
25、trength characteristics to be measured.Universal or standardized test methods of surface preparationdo not exist. Final machining steps may, or may not, negatemachining damage introduced during the initial machining.Thus, specimen fabrication history may play an important rolein the measured strengt
26、h distributions and shall be reported.6.3 Bending in uniaxially loaded shear tests can cause orpromote non-uniform stress distributions that may alter thedesired state of stress during the test. For example, non-uniform loading will occur if the loading surfaces of the testspecimen are not flat and
27、parallel.6.4 Fractures that initiate outside the gage section of aspecimen may be due to factors such as localized stressconcentrations, extraneous stresses introduced by improperloading configurations, or strength-limiting features in themicrostructure of the specimen. Such non-gage section frac-tu
28、res will normally constitute invalid tests.6.5 For the evaluation of the interlaminar shear strength bythe compression of a double-notched specimen, the distancebetween the notches has an effect on the maximum load andFIG. 1 Schematic of Compression of Double-Notched Specimenfor the Determination of
29、 Interlaminar Shear Strength of CFCCsC1425052therefore on the interlaminar shear strength.3,4,5It has beenfound that the stress distribution in the gage section of thespecimen is independent of the distance between the notcheswhen the notches are far apart. However, when the distancebetween the notc
30、hes is such that the stress fields around thenotches interact, the measured interlaminar shear strengthincreases. Because of the complexity of the stress field aroundeach notch and its dependence on the properties and homoge-neity of the material, conduct a series of tests on specimenswith different
31、 spacing between the notches to determine theeffect of notch separation on the measured interlaminar shearstrength.6.6 For the evaluation of the interlaminar shear strength bythe compression of a double-notched specimen, excessiveclamping forces will reduce the stress concentration around thenotches
32、 and, therefore, artificially increase the measured inter-laminar shear strength. Excessive clamping might occur ifinterference between the fixture and the specimen results frommismatch in their thermal expansion. Section 7.6 providesguidance to prevent this problem.6.7 The interlaminar shear streng
33、th of 1-D and 2-D CFCCsis controlled either by the matrix-rich interlaminar regions orby the weakest of the fiber-matrix interfaces. Whetherinterlaminar-shear failure initiates at the matrix-rich interlami-nar region or at the weakest of the fiber/matrix interfacesdepends on the location of the root
34、 of the notch, where theinterlaminar shear stress is largest, with respect to the inter-laminar microstructural features.7. Apparatus7.1 Testing MachinesThe testing machine shall be inconformance with Practices E4. The loads used in determiningshear strength shall be accurate within 61 % at any load
35、 withinthe selected load range of the testing machine as defined inPractices E4.7.2 Heating ApparatusThe apparatus for, and method of,heating the specimens shall provide the temperature controlnecessary to satisfy the requirement of 10.2.7.2.1 Heating can be by indirect electrical resistance (heat-i
36、ng elements), indirect induction through a susceptor, or radiantlamp with the specimen in ambient air at atmospheric pressureunless other environments are specifically applied and re-ported. Note that direct resistance heating is not recommendedfor heating CFCCs due to possible differences of the el
37、ectricalresistance of the constituent materials which may producenonuniform heating of the specimen.7.3 Temperature-Measuring ApparatusThe method oftemperature measurement shall be sufficiently sensitive andreliable to ensure that the temperature of the specimen is withinthe limits specified in 10.2
38、.7.3.1 Primary temperature measurement shall be made withthermocouples in conjunction with potentiometers, millivolt-meters, or electronic temperature controllers or readout units,or combination thereof. Such measurements are subject to twotypes of error. Thermocouple calibration and instrument mea-
39、suring errors initially produce uncertainty as to the exacttemperature. Secondly, both thermocouples and measuringinstruments may be subject to variations over time. Commonerrors encountered in the use of thermocouples to measuretemperatures include: calibration error, drift in calibration dueto con
40、tamination or deterioration with use, lead-wire error,error arising from method of attachment to the specimen, directradiation of heat to the bead, heat conduction along thermo-couple wires, and so forth.7.3.2 Temperature measurements shall be made with ther-mocouples of known calibration. Represent
41、ative thermo-couples shall be calibrated from each lot of wires used formaking noble-metal (for example, platinum or rhodium) ther-mocouples. Except for relatively low temperatures of exposure,noble-metal thermocouples are eventually subject to error uponreuse. Oxidized noble-metal thermocouples sha
42、ll not be reusedwithout clipping back to remove wire exposed to the hot zone,re-welding, and annealing. Any reuse of noble-metal thermo-couples after relatively low-temperature use without this pre-caution shall be accompanied by re-calibration data demon-strating that calibration was not unduly aff
43、ected by theconditions of exposure.7.3.3 Measurement of the drift in calibration of thermo-couples during use is difficult. When drift is a problem duringtests, a method shall be devised to check the readings of thethermocouples monitoring the specimen temperature duringthe test. For reliable calibr
44、ation of thermocouples after use, thetemperature gradient of the test furnace must be reproducedduring the re-calibration.7.3.4 Temperature-measuring, controlling, and recording in-struments shall be calibrated against a secondary standard,such as precision potentiometer, optical pyrometer, or black
45、-body thyristor. Lead-wire error shall be checked with the leadwires in place as they normally are used. For thermocouplecalibration procedures refer to Test Method E 220 and Speci-fication E 230.7.4 Data AcquisitionAt a minimum, autographic recordsof applied load and cross-head displacement versus
46、time shallbe obtained. Either analog chart recorders or digital dataacquisition systems may be used for this purpose although adigital record is recommended for ease of later data analysis.Ideally, an analog chart recorder or plotter shall be used inconjunction with the digital data acquisition syst
47、em to providean immediate record of the test as a supplement to the digitalrecord. Recording devices must be accurate to 61 % of fullscale and shall have a minimum data acquisition rate of 10 Hzwith a response of 50 Hz deemed more than sufficient.7.5 Dimension-Measuring DevicesMicrometers and otherd
48、evices used for measuring linear dimensions must be accurateand precise to at least 0.01 mm.3Whitney, J. M., “Stress Analysis of the Double Notch Shear Specimen,”Proceedings of the American Society for Composites, 4th Technical Conference,Blacksburg, VA, Technomic Publishing Co., Oct. 3-5, 1989, pp.
49、 325.4Fang, N. J. J., and Chou, T. W., “Characterization of Interlaminar ShearStrength of Ceramic Matrix Composites,” Journal Am. Ceram. Soc., 76, 10 1993,pp. 2539-48.5Lara-Curzio, E., and Ferber, M. K., “Shear Strength of Continuous FiberReinforced Ceramic Composites,” in Thermal and Mechanical Test Methods andBehavior of Continuous Fiber Ceramic Composites, ASTM STP 1309M, G. Jenkins,S. T. Gonczy, E. Lara-Curzio, N. E. Ashgaugh, and L. P. Zawada, eds., AmericanSociety for Testing and Materials, Philadelphia, PA, 1996.C14250537.6 Test FixtureThe main purposes of the fixtu
