1、Designation: C1327 15Standard Test Method forVickers Indentation Hardness of Advanced Ceramics1This standard is issued under the fixed designation C1327; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、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 Vickersindentation hardness of advanced ceramics. In this test, apointed, square base,
3、 pyramidal diamond indenter of pre-scribed shape is pressed into the surface of a ceramic with apredetermined force to produce a relatively small, permanentindentation. The surface projection of the two diagonals of thepermanent indentation is measured using a light microscope.The average diagonal s
4、ize and the applied force are used tocalculate the Vickers hardness, which represents the materialsresistance to penetration by the Vickers indenter. Hardness iscomputed as the ratio of the force to the contact surface area.1.2 The values stated in SI units are to be regarded asstandard. No other un
5、its of measurement are included in thisstandard.1.3 UnitsWhen Knoop and Vickers hardness tests weredeveloped, the force levels were specified in units of grams-force (gf) and kilograms-force (kgf). This standard specifiesthe units of force and length in the International System ofUnits (SI); that is
6、, force in newtons (N) and length in mm orm. However, because of the historical precedent and contin-ued common usage, force values in gf and kgf units areoccasionally provided for information. This test method speci-fies that Vickers hardness be reported either in units of GPa, ora dimensionless Vi
7、ckers hardness number that has impliedunits of kgf/mm2.1.4 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
8、 of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE384 Test Method for Knoop and Vickers Hardness ofMaterialsE691 Practice for Conducting a
9、n Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI 10 Standard for the Use of the InternationalSystem of Units (SI): The Modern Metric System.2.2 European Standard:CEN ENV 843-4 Advanced Technical Ceramics, MonolithicCeramics, Mechanical Properties at Room Temperature,Par
10、t 4: Vickers, Knoop and Rockwell Superficial Hard-ness32.3 Japanese Standard:JIS R 1610 Testing Method for Vickers Hardness of HighPerformance Ceramics42.4 ISO Standard:ISO 65072 Metallic MaterialsHardness testVickerstestPart 2: HV0.2 to less than HV553. Terminology3.1 Definitions:3.1.1 Vickers hard
11、ness number (HV), nan expression ofhardness obtained by dividing the force applied to a Vickersindenter by the surface area of the permanent impression madeby the indenter.1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subcom
12、mittee C28.01 onMechanical Properties and Performance.Current edition approved Jan. 1, 2015. Published March 2015. Originallyapproved in 1996. Last previous edition approved in 2008 as C1327- 08. DOI:10.1520/C1327-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AST
13、M Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from European Committee for Standardization (CEN), 36 rue deStassart, B-1050, Brussels, Belgium, http:/www.cenorm.be.4Available from
14、Japanese Standards Organization (JSA), 4-1-24 AkasakaMinato-Ku, Tokyo, 107-8440, Japan, http:/www.jsa.or.jp.5Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.Copyright ASTM International,
15、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2 Vickers indenter, na square-based pyramidal-shapeddiamond indenter with face angles of 136 00.4. Summary of Test Method4.1 This test method describes an indentation hardness testusing a calibrated machine to fo
16、rce a pointed, square base,pyramidal diamond indenter having specified face angles,under a predetermined force, into the surface of the materialunder test and to measure the surface-projected diagonals ofthe resulting impression after removal of the force.NOTE 1A general description of the Vickers i
17、ndentation hardness testis given in Test Method E384. 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
18、 also for advanced 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 ar
19、e measured. Vickers hardness is calculated from theratio of the applied force 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 force to the projected are
20、a onthe specimen surface.)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
21、 scope and should be usedwith caution, except for special cases where a reliable basis forthe conversion has been obtained by comparison tests.5.3 Vickers indentation diagonal lengths are approximately2.8 times shorter than the long diagonal of Knoop indentations,and the indentation depth is approxi
22、mately 1.5 times deeperthan Knoop indentations made at the same force.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 t
23、o causecracks in advanced ceramics than 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
24、the indentation tips or sides.5.6 A full hardness characterization includes measurementsover a broad range of indentation forces. Vickers hardness ofceramics usually decreases with increasing indentation size orindentation force, as shown in Fig. 1. The trend is known as theindentation size effect (
25、ISE). Hardness approaches a plateauconstant hardness at sufficiently large indentation size orforces. The test forces or loads that are needed to achieve aconstant hardness vary with the ceramic. The test forcespecified in this standard is intended to be sufficiently large thathardness is either clo
26、se to or on the plateau, but not so large asto introduce excessive cracking. A comprehensive character-ization of the ISE is recommended but is beyond the scope ofthis test method, which measures hardness at a single, desig-nated force.6. Interferences6.1 Cracking from the indentation tips can inter
27、fere withdetermination of tip location and thus the diagonal 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
28、 time-dependent manner (minutes or hours) after the impression 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 i
29、n the optical microscope, itmay be difficult to obtain a sharp 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 E384.7. Apparatus7.1 Testing Machines:7.1.1 There are three gene
30、ral types of machines available forconducting this test. One type is a self-contained unit built forthis purpose that uses deadweights (masses) on a pan or leverFIG. 1 Indentation Size Effect (ISE) Curves for a Ceramic (Some-times they continuously approach a plateau hardness at largerforces, but so
31、metimes they can have a shift or step if crackingoccurs.)C1327 152beam to carefully apply force to the test piece. There is no loadcell to record the force during the test sequence. The machinehas a built-in compound optical microscope for measuring theindentation sizes. The second type is an access
32、ory to existingcompound optical microscopes. Usually, this second type isfitted on an inverted-stage microscope. The third, more moderntype, is a self-contained unit built for this purpose which has abuilt-in load cell that controls a ram or crosshead that movesthe indenter into contact with the tes
33、t piece. The peak force andrate of force application can be controlled by a closed-loopfeedback circuit. The machine has a built-in compound opticalmicroscope for measuring the indentation sizes. Descriptionsof the various machines are available (1-3).67.1.2 Design of the machine should be such that
34、 the forceapplication rate, dwell time, and applied force can be set withinthe limits set forth in 10.5. It is an advantage to eliminate thehuman element whenever possible by appropriate machinedesign. The machine should be designed so that vibrationsinduced at the beginning of a test will be damped
35、 out by thetime the indenter touches the sample.7.1.3 The calibration of the balance beam or force applica-tion system should be checked monthly or as needed. Inden-tations in standard reference materials may also be used tocheck calibration when needed.7.2 Indenter:7.2.1 The indenter shall meet the
36、 specifications for Vickersindenters. See paragraph A1.3.5.1 of Test Method E384. Thefour edges formed by the four faces of the indenter shall besharp. Chamfered edges (as in Ref (4) are not permitted. Thetip offset shall be not more than 0.5 m in length.7.2.2 Fig. 2 shows the indenter. The depth of
37、 the indentationis17 the length of the diagonal. The indenter has an anglebetween 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
38、384 and is especiallypertinent to Vickers indenters used for advanced ceramics. 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. Indentersmay a
39、lso be inspected with an optical microscope with at least 500power, but care should be taken to avoid damaging the microscope lens.Indentations can be made into soft copper to help determine if a chip orcrack is present. A visual inspection of the resulting indentation may besufficient to verify the
40、 absence of defects from the shape of indentationsperformed on test blocks.7.3 Measuring Microscope:7.3.1 The measurement system shall be constructed so thatthe length of the diagonals can be determined with errors notexceeding 6 0.5 m (60.0005 mm).NOTE 3Stage micrometers with uncertainties less tha
41、n this shall beused to establish calibration constants for the microscope. See TestMethod E384, paragraph A1.3.3, Verification of the Indentation Measur-ing System. Ordinary stage micrometers that are used for determining theapproximate magnification of photographs may be too coarsely ruled ormay no
42、t have the required 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 increases as theresolving power and NA of a lens increases. However, the variation ismuch less than that observed in Kno
43、op indentations (2), (5), (6). The rangeof NA specified by this test method corresponds to 40 to 100 objectivelenses. The higher power lenses may have higher resolution, but thecontrast between the indentation tips and the polished surface may be less.This numerical aperture requirement is similar t
44、o, but more specific thanthat in Test Method E384. The requirement is different because manywhite or grey ceramics are transparent or translucent, and tip imaging ismore difficult.7.3.3 A filter may be used to provide monochromaticillumination. Green filters have proved to be useful.7.3.4 If indenta
45、tion diagonal sizes are measured from digitalimages acquired from a digital camera, then follow themanufacturers guidelines for use of the camera, the computermonitor, and the software. It is strongly recommended to use acalibrated stage micrometer to verify the precision and accu-racy of the length
46、 measuring procedure. The camera pixelcount, the monitor pixel count and resolution, and the lengthmeasuring software shall be such that the requirements of 7.3.1can be met.8. Test Specimens8.1 The Vickers indentation hardness test is adaptable to awide variety of advanced ceramic specimens. In gene
47、ral, theaccuracy of the test will depend on the smoothness of thesurface and, whenever possible, ground and polished speci-mens 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
48、thick as the indentation depth, the test will not be affected.In general, if specimens are at least 0.50 mm thick, thehardness 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 m6The boldf
49、ace numbers in parentheses refer to the list of references at the end ofthis test method.FIG. 2 Vickers IndenterC1327 153rms. However, if one is investigating a surface coating ortreatment, one cannot grind and polish the specimen.NOTE 5This requirement is 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 cer
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