1、Designation: D 1474 98 (Reapproved 2002)Standard Test Methods forIndentation Hardness of Organic Coatings1This standard is issued under the fixed designation D 1474; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope *1.1 These test methods cover the determinat
3、ion of theindentation hardness of organic materials such as dried paint,varnish, and lacquer coatings, when applied to an acceptableplane rigid surface, for example, metal or glass.1.2 Two methods are covered as follows:SectionsMethod AKnoop Indentation Hardness 6-12Method BPfund Indentation Hardnes
4、s 13-191.3 Method A, which has the greater precision, provideshardness values in terms of Knoop Hardness Number (KHN).Method B provides hardness in terms of Pfund HardnessNumber (PHN). Although the hardness value scales of thesemethods differ, the methods agree in the ranking of coatinghardness.1.4
5、Test Method A of these test methods is similar in content(but not technically equivalent) to ISO 6441-1 and ISO 6441-2.1.5 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.6 This standard does not purport to address th
6、e safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 823 Practices for Producing Fi
7、lms of Uniform Thicknessof Paint, Varnish, and Related Products on Test Panels2D 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using Micrometers2D 1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base2D 14
8、00 Test Method for Nondestructive Measurement ofDry-Film Thickness of Nonconductive Coatings Appliedto a Nonferrous Metal Base2E 384 Test Method for Microindentation Hardness of Ma-terials32.2 Other Standards:ISO 6441-1 Hardness testingPart 1: Determination ofKnoop hardness by measurement of the ind
9、entation lengthusing a microscope4ISO 6441-2 Hardness testingPart 2: Determination ofKnoop hardness by measurement of the indentation depth43. Terminology3.1 Definitions:3.1.1 indentation hardnessthe resistance to penetration byan indenter.3.1.2 Knoop indentera pyramidal diamond of prescribeddimensi
10、ons.3.1.3 Pfund indenterhemispherical quartz or sapphire in-denter of prescribed dimensions.3.1.4 Knoop hardness number, KHNthe indentation hard-ness determined with a Knoop indenter, and calculated asfollows:KHN 5 L/Ap5 L/l2Cp(1)where:L = load applied to the indenter, kg,l = measured length of long
11、 diagonal of the indentation,mm,Cp= indenter constant relating l2to Ap, andAp= projected area of indentation, mm2.3.1.5 Pfund hardness number, PHNthe indentation hard-ness determined with a Pfund indenter, and calculated asfollows:PHN 5 L/A 5 4L/pd25 1.27 L/d2! (2)where:L = load/kg applied to the in
12、denter, kg,A = area of projected indentation, mm2, andd = diameter of projected indentation, mm.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.23 on Physical Propertie
13、s of Applied PaintFilms.Current edition approved Dec. 10, 1998. Published February 1999. Originallypublished as D 1474 57 T. Last previous edition D 1474 92.2Annual Book of ASTM Standards, Vol 06.01.3Annual Book of ASTM Standards, Vol. 03.01.4Available from American National Standards Institute (ANS
14、I), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 Indentation hardness measurements have prov
15、en to beuseful in rating coatings on rigid substrates for their resistanceto mechanical abuse, such as that produced by blows, gouging,and scratching. These measurements do not necessarily char-acterize the resistance to mechanical abuse of coatings that arerequired to remain intact when deformed.5.
16、 Test Specimens5.1 The substrate for the coating shall be an acceptableplane rigid surface such as glass or metal.5.2 The coating thickness on any one panel shall be uniformwithin 0.1 mil (3 m). Coatings to be compared shall be ofequal thickness within 0.2 mil (5 m). For maximum accuracy,the minimum
17、 permissible coating thickness shall be such thatthe depth of indentation does not exceed three fourths of thecoating thickness, to minimize the effect of the substrate.5.3 At least three replicate specimens shall be tested foreach coating to be evaluated.5.4 Coatings should be applied in accordance
18、 with PracticesD 823 and their dry film thickness should be measured inaccordance with Test Methods D 1005, D 1186, or D 1400.5.5 From precoated sheets cut at least three specimens. Useonly plane (flat) sheets and round the edges slightly. Thecoating shall be free of oil and other foreign matter. Me
19、asurethe film thickness as in 5.4.METHOD AKNOOP INDENTATION HARDNESS6. Summary of Method6.1 This method consists of applying a load to the surface ofa coating by means of a pyramidal shaped diamond havingspecified face angles, and converting the measurements of theresultant permanent impression to a
20、 hardness number.7. Apparatus7.1 Hardness Tester,5consisting of a load applicator, aKnoop indenter, and a microscope fitted with a movablemicrometer stage. The apparatus shall mechanically bring theindenter into contact with the test surface with negligibleimpact, apply the selected full load, maint
21、ain it for 18 60.5 s,and withdraw the indenter.7.2 Knoop IndenterThe Knoop indenter is a pyramidaldiamond with included longitudinal angles of 172 308 andincluded transverse angle of 130 08.NOTE 1The ratio of the long to the short diagonal of the impressionis approximately 7:1; the ratio of the long
22、 diagonal to the depth ofpenetration is approximately 30:1.7.3 MicroscopeThe microscope shall have a filar mi-crometer eyepiece and sufficient objectives to permit themeasurement of the length of impression to within 61 %. Thespecimen shall be firmly supported on a movable micrometerstage attached t
23、o the microscope.8. Calibration8.1 Adjust the illumination in the microscope to givemaximum contrast when viewing an indentation.8.2 By means of a calibrated scale, determine the factor foreach microscope objective that converts the filar scale units ofthe eyepiece to millimetres.8.3 With a 25-g loa
24、d on the indenter, determine the KHN ofa calibrated standard (Note 2) with an assigned value notgreater than 50 KHN. If the obtained value is within 65%ofthe assigned value, the instrument is considered to be incalibration.NOTE 2A suitable source of standard reference materials in thishardness range
25、 is available from the U.S. National Institute for Standardsand Technology.6By agreement of the parties concerned, a stablespecimen (such as an aged coating or a baked enamel applied to a flatsubstrate) could be used to calibrate the participating hardness testers.9. Procedure9.1 Unless otherwise sp
26、ecified, make the hardness determi-nations at 73.5 63.50F (23 62C) and 50 65 % relativehumidity after equilibrating the specimens under these condi-tions for at least 24 h.9.2 Rigidly attach the specimen to the movable stage so thatthe surface to be measured is normal to the direction ofindentation.
27、 Mount the panel so that is cannot move withrespect to the stage in any direction during the test.9.3 Use the microscope to select an area of the test specimenthat is free of surface irregularities and imperfections. Placethis area under the indenter by means of the movable microme-ter stage.NOTE 3I
28、f good impressions cannot be obtained because of theroughness of the surface of the specimen, gently polish the surface withNo. 400 carborundum and finish off with jewelers rouge before making theimpression.9.4 Present the apparatus to apply a load that permits thelength of identification to read ac
29、curately but does not causethe depth of indentation to exceed three-quarters of the coatingfilm thickness. Start the test cycle so that the indenter ismechanically brought into contact with the mounted specimenunder a load of 25 g and full load is applied, maintained for 1860.5 s, and removed. For m
30、aximum accuracy, ensure that theindenter has not penetrated the coating to a depth beyond threefourths of the coating thickness. This is necessary to eliminateany major substrate effect on the hardness values.NOTE 4For maximum accuracy, care must be taken that the indenterdoes not penetrate the coat
31、ing to a depth beyond three fourths of thecoating thickness. This is necessary to eliminate any major substrate effecton the hardness measurement.9.5 Immediately after the completion of the cycle, adjust themovable stage so that the indentation is in the field of themicroscope. Focus the microscope
32、on the indentation so thatboth extremities of the long diagonal (that is, where the upperedges of the indentation just converge) are as sharp as possible.Measure the length of the long diagonal of the impression withthe filar micrometer eyepiece.5A hardness tester meeting the apparatus requirements
33、for this method is theTukon Microhardness Tester, available from the Wilson Instruments, Inc., Divisionof Instron, 100 Royall St., Canton, MA 02021.6Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.D 14742NOTE 5Select a micro
34、scope objective that will cause the length ofimpression to be between 200 and 800 filar units to assure maximumaccuracy in measurement.9.6 From the measurements obtained in 9.5, the informationgiven in Note 1, and the measured film thickness at the placeof indentation, calculate the depth of indente
35、r penetration. Ifthe depth of penetration exceeds three-fourths of the coatingthickness, the results may be influenced by substrate proximity.Consequently, repeat the test with specimens having a greaterfilm thickness or with a lighter load on the indenter.9.7 Since the applied load is not always th
36、e same and,practically never 25 g, calculate the Knoop Hardness Numberusing the equation provided by the manufacturer:KHN 5 L/l2Cp(3)where:L = load applied, kg, to the indenter,l = length of long diagonal of indentation, mm, andCp= indenter constant = 7.028 3 102.9.8 The Knoop Hardness Numbers for a
37、 test load of 1 gf andlength of long diagonal of indentation from 1.0 to 200.9 m aregiven in Table 1 of Test Method E 384.10. Calculation10.1 Calculate the mean indentation length in filar units.10.2 Convert this mean indentation length to KHN bymeans of the appropriate tables supplied with the inst
38、rument.NOTE 6If a conversion table is not available, the KHN may becalculated as follows:KHN 5 0.025/l2Cp(4)where:0.025 = load applied, kg, to the indenter,l = length of long diagonal of indentation, mm, andCp= indenter constant = 7.028 3 102.11. Report11.1 Report the following information:11.1.1 Me
39、an and range of KHN values obtained for eachspecimen, stating the number of indentations made and theindenter load used,11.1.2 Mean film thickness of each specimen, based on themeasurements made at the points of indentation,11.1.3 Specimen preparation and conditioning techniquesused, and11.1.4 Mean
40、and range of KHN values of the replicatepanels.12. Precision and Bias12.1 PrecisionOn the basis of an interlaboratory test ofthis method in which operators in six laboratories tested sevencoated panels having a broad range of hardness, the within-laboratory coefficient of variation was found to be 3
41、 % with 21degrees of freedom and the between-laboratories coefficient ofvariation 8 % with 30 degrees of freedom. Based upon thesecoefficients, the following criteria should be used for judgingthe acceptability of results at the 95 % confidence level:12.1.1 RepeatabilityTwo results, each the mean of
42、 threedeterminations on a specimen, obtained by the same operatorshould be considered suspect if they differ by more than 9 % oftheir mean value.12.1.2 ReproducibilityTwo results, each the mean of threedeterminations on a specimen, obtained by operators in differ-ent laboratories should be considere
43、d suspect if they differ bymore than 24 % of their mean value.12.1.3 BiasThe bias for the procedure Test Method A formeasuring indentation hardness using the Knoop indenter willbe determined using data previously generated in round-robintesting.METHOD BPFUND INDENTATION HARDNESS13. Summary of Method
44、13.1 This method consists of applying a load to the surfaceof a coating, by means of a transparent colorless quartz orsynthetic sapphire hemisphere having a specified diameter, andconverting the measurement of the resultant observed impres-sion under load to a hardness number.14. Apparatus14.1 Hardn
45、ess Testersconsisting of a load applicator, aPfund quartz or sapphite indenter, and a microscope with astage. The apparatus shall be constructed so as to permit theindenter to be brought manually into contact with the specimensurface with negligible impact.14.2 Pfund Indenter7 The Pfund indenter (Fi
46、g. 1) is atransparent colorless quartz or synthetic sapphire hemispherewith a spherical radius of 0.125 in. (3.18 mm) and a maximumspherical eccentricity of 0.002 in. (0.05 mm).14.3 MicroscopeThe microscope shall have a filar mi-crometer eyepiece and sufficient objectives to permit themeasurement of
47、 the diameter of impression to within 61%.The specimen shall be rigidly supported on the microscopestage.14.4 Timer, capable of measuring a time interval of 60 60.5s.15. Standardization15.1 Adjust the illumination in the microscope to givemaximum contrast when viewing an indentation.15.2 By means of
48、 a calibrated scale, determine the factor foreach microscope objective that converts the filar scale units ofthe eyepiece to millimetres.15.3 With a 1.0-kg load on the indenter, determine the PHNof a calibrated standard (Note 2) with an assigned value notgreater than 40 PHN. If the value obtained is
49、 within 65%ofthe assigned value, the instrument is considered to be incalibration.16. Procedure16.1 Unless otherwise specified, make the hardness deter-mination at 73.5 63.5F (23 62C) and 50 65 % relativehumidity, after holding the specimens under these conditionsfor not less than 24 h.7A hardness tester meeting the apparatus requirements of this test method is thePfund Indentation Hardness Tester. The instrument is no longer manufactured, butmany are still in use.D 1474316.2 Rigidly attach the specimens to the instrument stagesuch that the surface
