1、Designation: C 1327 03Standard Test Method forVickers Indentation Hardness of Advanced Ceramics1This standard is issued under the fixed designation C 1327; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、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 covers the determination of the Vickersindentation hardness of advanced ceramics.1.2 This standard does not purport
3、 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.2. Referenced Documents2.1 ASTM Standards:2E 4 Pr
4、actices for Force Verification of Testing MachinesE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 380 Practice for Use of the International System of Units(SI) (the Modernized Metric System)E 384 Test Method for Microhardness of MaterialsE 691 Practice for Conducting an I
5、nterlaboratory Study toDetermine the Precision of a Test Method2.2 European Standard:CEN ENV 843-4 Advanced Technical Ceramics, Mono-lithic Ceramics, Mechanical Properties at Room Tempera-ture, Part 4: Vickers, Knoop and Rockwell SuperficialHardness32.3 Japanese Standard:JIS R 1610 Testing Method fo
6、r Vickers Hardness of HighPerformance Ceramics42.4 ISO Standard:ISO 6507/2 Metallic MaterialsHardness testVickerstestPart 2: HV0.2 to less than HV553. Terminology3.1 Definition:3.1.1 Vickers hardness number (HV), nan expression ofhardness obtained by dividing the force applied to a Vickersindenter b
7、y the surface area of the permanent impression madeby the indenter.3.1.2 Vickers indenter, na square-based pyramidal-shapeddiamond indenter with face angles of 136 008.4. Summary of Test Method4.1 This test method describes an indentation hardness testusing a calibrated machine to force a pointed, s
8、quare base,pyramidal diamond indenter having specified face angles,under a predetermined load, into the surface of the materialunder test and to measure the surface-projected diagonals ofthe resulting impression after removal of the load.NOTE 1A general description of the Vickers indentation hardnes
9、s testis given in Test Method E 384. The present method is very similar, hasmost of the same requirements, and differs only in areas required by thespecial nature of advanced ceramics. This test method also has manyelements in common with standards ENV 843-4 and JIS R 1610, whichare also for advance
10、d ceramics.5. Significance and Use5.1 For advanced ceramics, Vickers indenters are used tocreate indentations whose surface-projected diagonals are mea-sured with optical microscopes. The Vickers indenter creates asquare impression from which two surface-projected diagonallengths are measured. Vicke
11、rs hardness is calculated from theratio of the applied load to the area of contact of the four facesof the undeformed indenter. (In contrast, Knoop indenters arealso used to measure hardness, but Knoop hardness is calcu-lated from the ratio of the applied load to the projected area onthe specimen su
12、rface.)5.2 Vickers indentation hardness is one of many propertiesthat is used to characterize advanced ceramics. Attempts havebeen made to relate Vickers indentation hardness to otherhardness scales, but no generally accepted methods are avail-able. Such conversions are limited in scope and should b
13、e usedwith caution, except for special cases where a reliable basis forthe conversion has been obtained by comparison tests.1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcommittee C28.01 onProperties and Performance.Curre
14、nt edition approved October 1, 2003. Published December 2003. Originallyapproved in 1996. Last previous edition approved in 1999 as C 1327 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vol
15、ume information, refer to the standards Document Summary page onthe ASTM website.3Available from European Committee for Standardization, Brussels, Belgium.4Available from Japanese Standards Association, Tokyo, Japan.5Available from International Standards Organization, Geneva, Switzerland.1Copyright
16、 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Vickers indentation diagonal lengths are approximately2.8 times shorter than the long diagonal of Knoop indentations,and the indentation depth is approximately 1.5 times deeperthan Knoop inde
17、ntations made at the same load.5.4 Vickers indentations are influenced less by specimensurface flatness, parallelism, and surface finish than Knoopindentations, but these parameters must be considered none-theless.5.5 Vickers indentations are much more likely to causecracks in advanced ceramics than
18、 Knoop indentations. Thecracks may influence the measured hardness by fundamentallyaltering the deformation processes that contribute to theformation of an impression, and they may impair or precludemeasurement of the diagonal lengths due to excessive damageat the indentation tips or sides.5.6 A ful
19、l hardness characterization includes measurementsover a broad range of indentation forces. Vickers hardness ofceramics usually decreases with increasing indentation size orindentation force. The trend is known as the indentation sizeeffect (ISE). Hardness approaches a plateau constant hardnessat suf
20、ficiently large indentation size or forces. The test forces orloads that are needed to achieve a constant hardness vary withthe ceramic. The test force specified in this standard is intendedto be sufficiently large that hardness is either close to or nearthe plateau, but not so large as to introduce
21、 excessive cracking.A comprehensive characterization of the ISE is recommendedbut is beyond the scope of this test method, which measureshardness at a single, designated force.6. Interferences6.1 Cracking from the indentation tips can interfere withdetermination of tip location and thus the diagonal
22、 lengthmeasurements.6.2 Cracking or spalling around the Vickers impression mayoccur and alter the shape and clarity of the indentation,especially for coarse-grained ceramics whereby grains maycleave and dislodge. The cracking may occur in a time-dependent manner (minutes or hours) after the impressi
23、on ismade.6.3 Porosity (either on or just below the surface) mayinterfere with measuring Vickers hardness, especially if theindentation falls directly onto a large pore or if the indentationtip falls in a pore.6.4 At higher magnifications in the optical microscope, itmay be difficult to obtain a sha
24、rp contrast between theindentation tip and the polished surface of some advancedceramics. This may be overcome by careful adjustment of thelighting as discussed in Test Method E 384.7. Apparatus7.1 Testing Machines:7.1.1 There are two general types of machines available formaking this test. One type
25、 is a self-contained unit built for thispurpose, and the other type is an accessory available to existingmicroscopes. Usually, this second type is fitted on an inverted-stage microscope. Descriptions of the various machines areavailable (13).67.1.2 Design of the machine should be such that the loadi
26、ngrate, dwell time, and applied load can be set within the limitsset forth in 10.5. It is an advantage to eliminate the humanelement whenever possible by appropriate machine design.The machine should be designed so that vibrations induced atthe beginning of a test will be damped out by the time thei
27、ndenter touches the sample.7.1.3 The calibration of the balance beam should be checkedmonthly or as needed. Indentations in standard referencematerials may also be used to check calibration when needed.7.2 Indenter:7.2.1 The indenter shall meet the specifications for Vickersindenters. See Test Metho
28、d E 384. The four edges formed bythe four faces of the indenter shall be sharp. Chamfered edges(as in Ref (4) are not permitted. The tip offset shall be notmore than 0.5 m in length.7.2.2 Fig. 1 shows the indenter. The depth of the indentationis17 the length of the diagonal. The indenter has an angl
29、ebetween opposite faces of 136 0 min (630 min).7.2.3 The diamond should be examined periodically; and ifit is loose in the mounting material, chipped, or cracked, it shallbe replaced.NOTE 2This requirement is from Test Method E 384 and is especiallypertinent to Vickers indenters used for advanced ce
30、ramics. Vickersindenters are often used at high loads in advanced ceramics in order tocreate cracks. Such usage can lead to indenter damage. The diamondindenter can be examined with a scanning electron microscope, or indentscan be made into soft copper to help determine if a chip or crack is present
31、.7.3 Measuring Microscope:6The boldface numbers in parentheses refer to the list of references at the end ofthis test method.FIG. 1 Vickers IndenterC 1327 0327.3.1 The measurement system shall be constructed so thatthe length of the diagonals can be determined with errors notexceeding6 0.0005 mm.NOT
32、E 3Stage micrometres with uncertainties less than this should beused to establish calibration constants for the microscope. See TestMethod E 384. Ordinary stage micrometres, which are intended fordetermining the approximate magnification of photographs, may be toocoarsely ruled or may not have the r
33、equired accuracy and precision.7.3.2 The numerical aperture (NA) of the objective lensshall be between 0.60 and 0.90.NOTE 4The apparent length of a Vickers indentation will increase asthe resolving power and NA of a lens increases. The variation is much lessthan that observed in Knoop indentations,
34、however (2), (5), (6). The rangeof NA specified by this test method corresponds to 40 to 1003 objectivelenses. The higher power lenses may have higher resolution, but thecontrast between the indentation tips and the polished surface may be less.7.3.3 A filter may be used to provide monochromaticillu
35、mination. Green filters have proved to be useful.8. Test Specimens8.1 The Vickers indentation hardness test is adaptable to awide variety of advanced ceramic specimens. In general, theaccuracy of the test will depend on the smoothness of thesurface and, whenever possible, ground and polished speci-m
36、ens should be used. The back of the specimen shall be fixedso that the specimen cannot rock or shift during the test.8.1.1 ThicknessAs long as the specimen is over ten timesas thick as the indentation depth, the test will not be affected.In general, if specimens are at least 0.50 mm thick, thehardne
37、ss will not be affected by variations in the thickness.8.1.2 Surface FinishSpecimens should have a ground andpolished surface. The roughness should be less than 0.1 mrms. However, if one is investigating a surface coating ortreatment, one cannot grind and polish the specimen.NOTE 5This requirement i
38、s necessary to ensure that the surface is flatand that the indentation is sharp. Residual stresses from polishing are ofless concern for most advanced ceramics than for glasses or metals.References (7) and (8) report that surfaces prepared with 1 m or finerdiamond abrasive had no effect on measured
39、ceramic hardness. Hardnesswas only affected when the surface finish had an optically resolvableamount of abrasive damage (7). (Extra caution may be appropriate duringpolishing of transformation toughening ceramics, such as some zirconias,since the effect upon hardness is not known.)9. Preparation of
40、 Apparatus9.1 Verification of LoadMost of the machines availablefor Vickers hardness testing use a loaded beam. This beamshall be tested for zero load. An indentation should not bevisible with zero load, but the indenter should contact thesample. Methods of verifying the load application are given i
41、nPractices E 4.9.2 Separate Verification of Load, Indenter, and MeasuringMicroscopeProcedures in Test Method E 384, Section 14,may be followed.9.3 Verification by Standard Reference MaterialsStandardreference blocks, SRM No. 2831, of tungsten carbide that areavailable from the National Institute of
42、Standards and Tech-nology7can be used to verify that an apparatus produces aVickers hardness within6 5 % of the certified value.10. Procedure10.1 Specimen PlacementPlace the specimen on the stageof the machine so that the specimen will not rock or shiftduring the measurement. The specimen surface sh
43、all be cleanand free of any grease or film.10.2 Specimen Leveling:10.2.1 The surface of the specimen being tested shall lie ina plane normal to the axis of the indenter. The angle of theindenter and specimen surface should be within 2 of perpen-dicular.NOTE 6Greater amounts of tilting produce nonuni
44、form indentationsand invalid test results. 2 tilt will cause an asymmetrical indentationwhich is just noticeable, and will cause a 1 % error in hardness (9).10.2.2 If one leg of a diagonal is noticeably longer than theother leg of the same diagonal, resulting in a deformedindentation, misalignment i
45、s probably present and should becorrected before proceeding with any measurements. See TestMethod E 384.10.2.3 Leveling the specimen is facilitated if one has aleveling device.810.3 Magnitude of Test LoadA test of 9.81 N (1 kgf) isspecified. If other forces are used because of a specialrequirement,
46、or due to cracking problems at 9.81 N, then thereporting procedure of 12.6 shall be used. If additional forcesare used (for example to measure the indentation size effecttrend), then the reporting procedure of 12.6 shall be used foreach data set.10.4 Clean the IndenterThe indenter shall be cleanedpr
47、ior to and during a test series. A cotton swab with ethanol,methanol, or isopropanol may be used. Indenting into softcopper also may help remove debris.NOTE 7Ceramic powders or fragments from the ceramic test piececan adhere to the diamond indenter.10.5 Application of Test Load:10.5.1 Start the mach
48、ine smoothly. The rate of indentermotion prior to contact with the specimen shall be 0.015 to0.070 mm/s. If the machine is loaded by an electrical system ora dash-pot lever system, it should be mounted on shockabsorbers which damp out all vibrations by the time theindenter touches the specimen.NOTE
49、8This rate of loading is consistent with Test Method E 384.10.5.2 The time of application of the full test load shall be15s(62) unless otherwise specified. After the indenter hasbeen in contact with the specimen from this required dwelltime, raise it carefully off the specimen to avoid a vibrationimpact.7National Institute of Standards and Technology, Standard Reference MaterialsProgram, Gaithersburg, MD 20899.8The sole source of supply of the apparatus known to the committee at this timeis the Tukon Tester leveling device, available from the Wilson Div
