1、Designation: C1469 10Standard Test Method forShear Strength of Joints of Advanced Ceramics at AmbientTemperature1This standard is issued under the fixed designation C1469; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 shearstrength of joints in advanced ceramics at ambient temperature.Test
3、 specimen geometries, test specimen fabrication methods,testing modes (that is, force or displacement control), testingrates (that is, force or displacement rate), data collection, andreporting procedures are addressed.1.2 This test method is used to measure shear strength ofceramic joints in test s
4、pecimens extracted from larger joinedpieces by machining. Test specimens fabricated in this way arenot expected to warp due to the relaxation of residual stressesbut are expected to be much straighter and more uniformdimensionally than butt-jointed test specimens prepared byjoining two halves, which
5、 are not recommended. In addition,this test method is intended for joints, which have either low orintermediate strengths with respect to the substrate material tobe joined. Joints with high strengths should not be tested bythis test method because of the high probability of invalid testsresulting f
6、rom fractures initiating at the reaction points ratherthan in the joint. Determination of the shear strength of jointsusing this test method is appropriate particularly for advancedceramic matrix composite materials but also may be useful formonolithic advanced ceramic materials.1.3 Values expressed
7、 in this test method are in accordancewith the International System of Units (SI) and IEEE/ASTM SI10 .1.4 This test method does not purport to address the safetyproblems associated with its use. It is the responsibility of theuser of this test method to establish appropriate safety andhealth practic
8、es and determine the applicability of regulatorylimitations prior to use. Specific precautionary statements arenoted in 8.1 and 8.2.2. Referenced Documents2.1 ASTM Standards:2C1145 Terminology of Advanced CeramicsC1161 Test Method for Flexural Strength of AdvancedCeramics at Ambient TemperatureC1211
9、 Test Method for Flexural Strength of AdvancedCeramics at Elevated TemperaturesC1275 Test Method for Monotonic Tensile Behavior ofContinuous Fiber-Reinforced Advanced Ceramics withSolid Rectangular Cross-Section Test Specimens at Ambi-ent TemperatureC1341 Test Method for Flexural Properties of Conti
10、nuousFiber-Reinforced Advanced Ceramic CompositesD3878 Terminology for Composite MaterialsD5379/D5379M Test Method for Shear Properties of Com-posite Materials by the V-Notched Beam MethodE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE
11、122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the Average for a Characteristicof a Lot or ProcessE337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)IEEE/ASTM SI 10 American National Standard for Use ofthe
12、International System of Units (SI): The Modern MetricSystem3. Terminology3.1 DefinitionsThe definitions of terms relating to shearstrength testing appearing in Terminology E6, to advancedceramics appearing in Terminologies C1145 and D3878 applyto the terms used in this test method. Additional terms
13、used inconjunction with this test method are defined as follows.3.1.1 advanced ceramic, nhighly-engineered, high-performance predominately nonmetallic, inorganic, ceramicmaterial having specific functional attributes. C11451This test method is under the jurisdiction of ASTM Committee C28 onAdvanced
14、Ceramics and is the direct responsibility of Subcommittee C28.07 onCeramic Matrix Composites.Current edition approved Dec. 1, 2010. Published January 2011. Originallyapproved in 2000. Last previous edition approved in 2005 as C1469 00 (2005).DOI: 10.1520/C1469-10.2For referenced ASTM standards, visi
15、t 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 19428-29
16、59, United States.3.1.2 breaking force F, nforce at which fracture occurs.3.1.3 ceramic matrix composite, nmaterial consisting oftwo or more materials (insoluble in one another), in which themajor, continuous component (matrix component) is a ceramicwhile the secondary component(s) may be ceramic, g
17、lass-ceramic, glass, metal, or organic in nature. These componentsare combined on macroscale to form a useful engineeringmaterial possessing certain properties or behavior not pos-sessed by the individual constituents. C12753.1.4 joining, ncontrolled formation of chemical, or me-chanical bond, or bo
18、th, between similar or dissimilar materials.3.1.5 shear strength F/L2, nmaximum shear stress that amaterial is capable of sustaining. Shear strength is calculatedfrom breaking force in shear and shear area.4. Summary of Test Method4.1 This test method describes an asymmetrical four-pointflexure test
19、 method to determine shear strengths of advancedceramic joints. Test specimens and test setup are shownschematically in Fig. 1 and Fig. 2, respectively. Selection of thetest specimen geometry depends on the bond strength of thejoint, which may be determined by preparing longer testspecimens of the s
20、ame cross-section and using a standardfour-point flexural strength test, for example, Test MethodC1161 for monolithic advanced ceramic base material and TestMethod C1341 for composite advanced ceramic base material.If the joint flexural strength is low (that is, 50 % of theflexural strength of the b
21、ase material) this test method shouldnot be used to measure shear strength of advanced ceramicjoints because very high contact stresses at the reaction pointswill provide a high probability of invalid tests (that is, fracturesnot at the joint).4.2 The testing arrangement of this test method is asym-
22、metrical flexure, as illustrated by the force, shear and momentdiagrams in Fig. 3a, Fig. 3b, and Fig. 3c, respectively. Note thatthe greatest shear exists over a region of 6 Si/2 around thecenterline of the joint (see Fig. 3b). In addition, while themoment is zero at the centerline of the joint, the
23、 maximummoments occur at the inner reaction points (see Fig. 3c). Thepoints of maximum moments are where the greatest probabilityof fracture of the base material may occur if the joint flexuralstrength, and therefore, joint shear strength is too high.5. Significance and Use5.1 Advanced ceramics are
24、candidate materials for struc-tural applications requiring high degrees of wear and corrosionresistance, often at elevated temperatures.5.2 Joints are produced to enhance the performance andapplicability of materials. While the joints between similarmaterials are generally made for manufacturing com
25、plex partsand repairing components, those involving dissimilar materialsusually are produced to exploit the unique properties of eachconstituent in the new component. Depending on the joiningprocess, the joint region may be the weakest part of thecomponent. Since under mixed-mode and shear loading,
26、theload transfer across the joint requires reasonable shear strength,it is important that the quality and integrity of joint underFIG. 2 Schematic of Test FixtureFIG. 3 Idealized a) Force, b) Shear, and c) Moment Diagrams forAsymmetric Four-point Flexure, Where Soand SiAre the Outerand Inner Reactio
27、n Span Distances, Respectively, and P is theApplied ForceC1469 103in-plane shear forces be quantified. Shear strength data are alsoneeded to monitor the development of new and improvedjoining techniques.5.3 Shear tests provide information on the strength anddeformation of materials under shear stres
28、ses.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 derived from stan-dardized shear test specimens may be considered indicative ofthe response of the material from
29、 which they were taken forgiven primary processing conditions and post-processing heattreatments.6. Interferences6.1 Fractures that initiate outside of the joint region may bedue to factors, such as localized stress concentrations, extra-neous stresses introduced by improper force transfer. Suchfrac
30、tures will constitute invalid tests.6.2 Since the joint width is typically small, that is, 0.05 to0.20 mm, the proper machining of the notches at the jointregion is very critical (see Fig. 1). Improper machining of thenotches can lead to undesired fracture at the reaction points.Furthermore, nonsymm
31、etrical machining of the nothces can bedecisive as to how the fracture occurs between the nothces.NOTE 1Finite element stress analysis of nonsymmetrical nothcesshowed that when there is a misalignment between the notches and themid-plane of the joint, spurious normal (sx) tensile stresses are genera
32、tedat the notches which tend to “tear” the joint and would artificially affect(reduce) the magnitude of shear strength measured from the joint. Themagnitude of these tensile stresses could be significant depending on thematerial system being investigated. Based on this analysis, it is recom-mended t
33、hat the ratio of misalignment between the notch root andmid-plane of the joint, d, and the distance between the notches, h, shouldbe kept to less than 0.0125. (See Fig. 4.)6.3 In this test method, the shear force required to causefracture in the joint region depends on the span lengths of Soand Siin
34、 the fixture3(see Fig. 3). These lengths and the strengthof the joint relative to that of the base material determinewhether fracture takes place at the joint region or at thereaction points. Depending on this relative strength, it may benecessary to conduct preliminary tests to establish the appro-
35、priate Soand Sidistances for the fixture to be used.46.4 The accuracy of insertion and alignment of the testspecimen with respect to the fixture is critical; therefore,preparations for testing should be done carefully to minimizethe bending moment at the joint, which strongly depends on theinner and
36、 outer reaction spans, as seen in Fig. 3c. See details in10.4.6.5 Test environment (vacuum, inert gas, ambient air, etc.)including moisture content, for example, relative humidity,may have an influence on the measured shear strength. Con-versely, testing can be conducted in environments and testingm
37、odes and rates representative of service conditions to evalu-ate material performance under those conditions. When testingis conducted in uncontrolled ambient air with the objective ofevaluating maximum strength potential, relative humidity andtemperature must be monitored and reported. Testing at h
38、u-midity levels 65 % RH is not recommended and any devia-tions from this recommendation shall be reported.7. Apparatus7.1 Testing MachinesThe testing machine shall be inconformance with Practices E4. The forces used in determiningshear strength shall be accurate within 61 % at any forcewithin the se
39、lected force range of the testing machine asdefined in Practices E4.7.2 Data AcquisitionAt a minimum, autographic recordsof applied force and cross-head displacement versus time shallbe obtained. Either analog chart recorders or digital dataacquisition systems may be used for this purpose although a
40、digital record is recommended for ease of later data analysis.Ideally, an analog chart recorder or plotter should be used inconjunction with the digital data acquisition system to providean immediate record of the test as a supplement to the digitalrecord. Recording devices shall be accurate to 61 %
41、 of fullscale and shall have a minimum data acquisition rate of 10 Hzwith a response of 50 Hz deemed more than sufficient.7.3 Dimension-Measuring DevicesMicrometers and otherdevices used for measuring linear dimensions must be accurateand precise to at least 0.01 mm.7.4 Combination SquareUsed to dra
42、w perpendicular linesto specimen axis at the locations of inner loading points. Thetolerance must be within 0.5.7.5 Test FixtureThe test fixture consists of top and bottomsections, reaction-pins, and a force transfer ball, as shownschematically in Fig. 2. The bottom section is placed on astationary
43、base, for example, a compression platen. The testspecimen is positioned between the top and bottom sections of3J.M. Slepetz, T.F. Zagaeski, and R.F. Novello, “In-Plane Shear Test forComposite Materials”, AMMRC-TR-78-30, Army Materials and Mechanics Re-search Center, Watertown, MA, July 1978.4. nal,
44、I.E. Anderson, and S.I. Maghsoodi, “ATest Method to Measure ShearStrength of Ceramic Joints at High Temperatures,” J. Am. Ceram. Soc., 80, 1281(1997).NOTE 1It is recommended that d/h ratio in both notch types is lessthan 0.0125.FIG. 4 Schematic of Misalignment, d, between the Joint Line andNotch Roo
45、t Shown for StraightNotched SpecimenC1469 104the fixture. The force is transmitted from the test machine to thefixture by the force transfer ball; however, a pin also can beused in place of the force transfer ball. Table 1 containssymbols, nomenclature, and recommended dimensions for thetest fixture
46、 (Fig. 2), where the tolerances for Soand Siafteralignment is 60.2 mm (see 10.4 for details). The tolerances forthe diameter of the force transfer ball and reaction-pin are 60.1mm and 60.01 mm, respectively.NOTE 2The reaction-pin diameter in this standard is 3 mm, unlike thatin Test Method C1161 whe
47、re it is a 4.5 mm. Unpublished finite elementanalyses have indicated that the smaller pin diameter better approximatesthe “point loading”, thus the stress profile at the joint in Fig. 3.NOTE 3It should be indicated that when there are restrictions for pinsto rotate freely, as in Fig. 2, the resultin
48、g friction may become a factor inthe measurements, as indicated in Test Method C1161. So far, however, nosystematic study has been conducted in the current test method regardingthis issue.7.5.1 Test fixtures, including the pins and ball, and loadingrams shall be stiff and elastic under loading. Thes
49、e pieces maybe made of a ceramic with an elastic modulus between 200 and400 GPa and a flexural strength no less than 275 MPa, asspecified in Test Method C1211. Dense high purity siliconcarbide and alumina are the typical candidate materials. Alter-natively, the above components may be made of hardened steelwhich has a hardness no less than HRC 40 or which has a yieldstrength no less than 1240 MPa, as specified in Test MethodC1161, C1211.8. Precautionary Statement8.1 During the conduct of this test method, the possibility offlying fragments of broken test mat
