1、Designation: C1425 11C1425 13Standard Test Method forInterlaminar Shear Strength of 1D and 2D ContinuousFiber-Reinforced Advanced Ceramics at ElevatedTemperatures1This standard is issued under the fixed designation C1425; 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. Scope Scope*1.1 This test method addresses the compression of a double-notch
3、ed test specimen to determine interlaminar shear strength ofcontinuous fiber-reinforced ceramic composites (CFCCs) at elevated temperatures. Failure of the test specimen occurs byinterlaminar shear between two centrally located notches machined halfway through the thickness of the test specimen and
4、spaceda fixed distance apart on opposing faces (see Fig. 1). Test specimen preparation methods and requirements, testing modes (forceor displacement control), testing rates (force rate or displacement rate), data collection, and reporting procedures are addressed.1.2 This test method is used for tes
5、ting advanced ceramic or glass matrix composites with continuous fiber reinforcement havinga laminated structure such as in unidirectional (1-D) or bidirectional (2-D) fiber architecture (lay-ups of unidirectional plies orstacked fabric). This test method does not address composites with nonlaminate
6、d structures, such as (3-D) fiber architecture ordiscontinuous fiber-reinforced, whisker-reinforced, or particulate-reinforced ceramics.1.3 Values expressed in this test method are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10.1.4 This standard does not purport to add
7、ress all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific precautionary statements are noted in 8.1 and 8.
8、2.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1292 Test Method for Shear Strength of Continuous Fiber-Reinforced Advanced Ceramics at Ambient TemperaturesD695 Test Method for Compressive Properties of Rigid PlasticsD3846 Test Method for In-Plane Shear Strength o
9、f Reinforced PlasticsD3878 Terminology for Composite MaterialsD6856/D6856M Guide for Testing Fabric-Reinforced “Textile” Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Esti
10、mate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE220 Test Method for Calibration of Thermocouples By Comparison TechniquesE230 Specification and Temperature-Electromotive Force (EMF) Tables for Standardized ThermocouplesE337 Test Method for Measuring Humidity with
11、a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)IEEE/ASTM SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric System1 This test method is under the jurisdiction of ASTM Committee C28 on Advanced Ceramics and is the direct responsibi
12、lity of Subcommittee C28.07 on Ceramic MatrixComposites.Current edition approved July 15, 2011Feb. 15, 2013. Published August 2011April 2013. Originally approved in 1999. Last previous edition approved in 20052011 asC1425 05.C1425 11. DOI: 10.1520/C1425-11.10.1520/C1425-13.2 For referencedASTM stand
13、ards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an AS
14、TM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published
15、 by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 DefinitionsThe definitions of terms relating to shea
16、r strength testing appearing in Terminology E6 apply to the terms usedin this test method. The definitions of terms relating to advanced ceramics appearing in Terminology C1145 apply to the terms usedin this test method. The definitions of terms relating to fiber-reinforced composites appearing in T
17、erminology D3878 apply to theterms used in this test method.3.2 Definitions of Terms Specific to This Standard:3.2.1 shear failure force (F), nmaximum force required to fracture a shear-loaded test specimen. (C1292)3.2.2 shear strength (FL-2), nmaximum shear stress that a material is capable of sust
18、aining. Shear strength is calculated fromthe failure force in shear and the shear area. (C1292)4. Summary of Test Method4.1 This test method addresses the determination of the interlaminar shear strength of CFCCs at elevated temperatures. Theinterlaminar shear strength of CFCCs, as determined by thi
19、s test method, is measured by loading in compression a double-notchedtest specimen of uniform width. Failure of the test specimen occurs by interlaminar shear between two centrally located notchesmachined halfway through the thickness of the test specimen and spaced a fixed distance apart on opposin
20、g faces. Schematics ofthe loading mode and the test specimen are shown in Fig. 1. The procedures in this test method are similar to those in Test MethodC1292 for the determination of the interlaminar shear strength of CFCCs at ambient temperature, except that the considerationsfor conducting the tes
21、t at elevated temperatures are addressed in this test method.FIG. 1 Schematic of Compression of Double-Notched Test Specimen for the Determination of Interlaminar Shear Strength of CFCCsC1425 1325. Significance and Use5.1 Continuous fiber-reinforced ceramic composites are candidate materials for str
22、uctural applications requiring high degreesof wear and corrosion resistance, and damage tolerance at high temperatures.5.2 The 1-D and 2-D CFCCs are highly anisotropic and their transthickness tensile and interlaminar shear strength are lowerthan their in-plane tensile and in-plane shear strength, r
23、espectively.5.3 Shear tests provide information on the strength and deformation of materials under shear stresses.5.4 This test method may be used for material development, material comparison, quality assurance, characterization, anddesign data generation.5.5 For quality control purposes, results d
24、erived from standardized shear test specimens may be considered indicative of theresponse of the material from which they were taken for given primary processing conditions and post-processing heat treatments.6. Interferences6.1 Test environment (vacuum, inert gas, ambient air, and so forth) includi
25、ng moisture content (for example, relative humidity)may have an influence on the measured interlaminar shear strength. In particular, the behavior of materials susceptible to slowcrack growth will be strongly influenced by test environment and testing rate. Testing to evaluate the maximum strength p
26、otentialof a material shall be conducted in inert environments or at sufficiently rapid testing rates, or both, so as to minimize slow crackgrowth effects. Conversely, testing can be conducted in environments and testing modes and rates representative of serviceconditions to evaluate material perfor
27、mance under those conditions. When testing is conducted in uncontrolled ambient air withthe objective of evaluating maximum strength potential, relative humidity and temperature must be monitored and reported.Testingat humidity levels 65 % RH is not recommended and any deviations from this recommend
28、ation must be reported.6.2 Preparation of test specimens, although normally not considered a major concern with CFCCs, can introduce fabricationflaws which may have pronounced effects on the mechanical properties and behavior (for example, shape and level of the resultingforce-displacement curve and
29、 shear strength). Machining damage introduced during test specimen preparation can be either arandom interfering factor in the determination of shear strength of pristine material, or an inherent part of the strengthcharacteristics to be measured. Universal or standardized test methods of surface pr
30、eparation do not exist. Final machining stepsmay, or may not, negate machining damage introduced during the initial machining. Thus, test specimen fabrication history mayplay an important role in the measured strength distributions and shall be reported.6.3 Bending in uniaxially loaded shear tests c
31、an cause or promote non-uniform stress distributions that may alter the desiredstate of stress during the test. For example, non-uniform loading will occur if the loading surfaces of the test specimen are not flatand parallel.6.4 Fractures that initiate outside the gage section of a test specimen ma
32、y be due to factors such as localized stressconcentrations, extraneous stresses introduced by improper loading configurations, or strength-limiting features in the microstruc-ture of the test specimen. Such non-gage section fractures will normally constitute invalid tests.6.5 For the evaluation of t
33、he interlaminar shear strength by the compression of a double-notched test specimen, the distancebetween the notches has an effect on the maximum force and therefore on the interlaminar shear strength.3 ,4,5 It has been foundthat the stress distribution in the gage section of the test specimen is in
34、dependent of the distance between the notches when thenotches are far apart. However, when the distance between the notches is such that the stress fields around the notches interact,the measured interlaminar shear strength increases. Because of the complexity of the stress field around each notch a
35、nd itsdependence on the properties and homogeneity of the material, conduct a series of tests on test specimens with different spacingbetween the notches to determine the effect of notch separation on the measured interlaminar shear strength.6.6 For the evaluation of the interlaminar shear strength
36、by the compression of a double-notched test specimen, excessiveclamping forces will reduce the stress concentration around the notches and, therefore, artificially increase the measuredinterlaminar shear strength. Excessive clamping might occur if interference between the test fixure and the test sp
37、ecimen resultsfrom mismatch in their thermal expansion. Section 7.6 provides guidance to prevent this problem.6.7 The interlaminar shear strength of 1-D and 2-D CFCCs is controlled either by the matrix-rich interlaminar regions or by theweakest of the fiber-matrix interfaces. Whether interlaminar-sh
38、ear failure initiates at the matrix-rich interlaminar region or at theweakest of the fiber/matrix interfaces depends on the location of the root of the notch, where the interlaminar shear stress is largest,with respect to the interlaminar microstructural features.3 Whitney, J. M., “Stress Analysis o
39、f 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. 325.4 Fang, N. J. J., and Chou, T. W., “Characterization of Interlaminar Shear Strength of Ceramic Matrix Composites,” Journa
40、l Am. Ceram. Soc., 76, 10 1993, pp. 2539-48.5 Lara-Curzio, E., and Ferber, M. K., “Shear Strength of Continuous Fiber Reinforced Ceramic Composites,” in Thermal and Mechanical Test Methods and Behavior ofContinuous Fiber Ceramic Composites, ASTM STP 1309M, G. Jenkins, S. T. Gonczy, E. Lara-Curzio, N
41、. E. Ashgaugh, and L. P. Zawada, eds., American Society for Testingand Materials, Philadelphia, PA, 1996.C1425 1337. Apparatus7.1 Testing MachinesThe testing machine shall be in conformance with Practices E4. The forces used in determining shearstrength shall be accurate within 61 % at any force wit
42、hin the selected force range of the testing machine as defined in PracticesE4.7.2 Heating ApparatusThe apparatus for, and method of, heating the test specimens shall provide the temperature controlnecessary to satisfy the requirement of 10.2.7.2.1 Heating can be by indirect electrical resistance (he
43、ating elements), indirect induction through a susceptor, or radiant lampwith the test specimen in ambient air at atmospheric pressure unless other environments are specifically applied and reported. Notethat direct resistance heating is not recommended for heating CFCCs due to possible differences o
44、f the electrical resistance of theconstituent materials which may produce nonuniform heating of the test specimen.7.3 Temperature-Measuring ApparatusThe method of temperature measurement shall be sufficiently sensitive and reliable toensure that the temperature of the test specimen is within the lim
45、its specified in 10.2.7.3.1 Primary temperature measurement shall be made with thermocouples in conjunction with potentiometers, millivoltmeters,or electronic temperature controllers or readout units, or combination thereof. Such measurements are subject to two types of error.Thermocouple calibratio
46、n and instrument measuring errors initially produce uncertainty as to the exact temperature. Secondly, boththermocouples and measuring instruments may be subject to variations over time. Common errors encountered in the use ofthermocouples to measure temperatures include: calibration error, drift in
47、 calibration due to contamination or deterioration withuse, lead-wire error, error arising from method of attachment to the test specimen, direct radiation of heat to the bead, heatconduction along thermocouple wires, and so forth.7.3.2 Temperature measurements shall be made with thermocouples of kn
48、own calibration. Representative thermocouples shallbe calibrated from each lot of wires used for making noble-metal (for example, platinum or rhodium) thermocouples. Except forrelatively low temperatures of exposure, noble-metal thermocouples are eventually subject to error upon reuse. Oxidizednoble
49、-metal thermocouples shall not be reused without clipping back to remove wire exposed to the hot zone, re-welding, andannealing. Any reuse of noble-metal thermocouples after relatively low-temperature use without this precaution shall beaccompanied by re-calibration data demonstrating that calibration was not unduly affected by the conditions of exposure.7.3.3 Measurement of the drift in calibration of thermocouples during use is difficult. When drift is a problem during tests, amethod shall be devised to check the readings of the thermocouples monitoring the test sp
