1、Designation: D1474/D1474M 13Standard Test Methods forIndentation Hardness of Organic Coatings1This standard is issued under the fixed designation D1474/D1474M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 These test methods cover the determination
3、 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 612Method BPfund Indentation Hardness 13
4、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 Test
5、MethodAof these test methods is similar in content(but not technically equivalent) to ISO 6441-1and ISO 6441-2.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem sh
6、all be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate
7、 safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thic
8、k-ness of Organic Coatings Using MicrometersD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous MetalsE384 Test Method for Knoop and Vickers Hardness ofMaterials2.2 Other S
9、tandards:ISO 6441-1 Paints and VarnishesDetermination of micro-indentation hardnessPart 1: Knoop hardness by mea-surement of the indentation length3ISO 6441-2 Paints and VarnishesDetermination of micro-indentation hardnessPart 2: Knoop hardness by mea-surement of the indentation depth under load33.
10、Terminology3.1 Definitions:3.1.1 indentation hardness, nthe resistance to penetrationby an indenter.3.1.2 Knoop indenter, na pyramidal diamond of pre-scribed dimensions.3.1.3 Pfund indenter, nhemispherical quartz or sapphireindenter of prescribed dimensions.3.1.4 Knoop hardness number, KHN, nthe ind
11、entationhardness 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 diagonal of the indentation,mm,Cp= indenter constant relating l2to Ap, andAp= projected area of indentation, mm2.1These test methods
12、 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 Properties of Applied PaintFilms.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1957.
13、 Last previous edition approved in 2008 as D1474 98 (2008).DOI: 10.1520/D1474_D1474M-13.2For referenced ASTM standards, visit 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 Summa
14、ry page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
15、en, PA 19428-2959. United States13.1.5 Pfund hardness number, PHN, nthe indentationhardness determined with a Pfund indenter, and calculated asfollows:PHN 5 L/A 5 4L/d25 1.27 L/d2! (2)where:L = load/kg applied to the indenter, kg,A = area of projected indentation, mm2, andd = diameter of projected i
16、ndentation, mm.4. Significance and Use4.1 Indentation hardness measurements have proven 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 resistan
17、ce to mechanical abuse of coatings that arerequired to remain intact when deformed.5. 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 3 m 0.1 mil. Coatings to be compare
18、d shall be ofequal thickness within 5 m 0.2 mil. For maximum accuracy,the minimum 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 te
19、sted foreach coating to be evaluated.5.4 Coatings should be applied in accordance with PracticesD823 and their dry film thickness should be measured inaccordance with Test Methods D1005 or D7091.5.5 From precoated sheets cut at least three specimens. Useonly plane (flat) sheets and round the edges s
20、lightly. Thecoating shall be free of oil and other foreign matter. Measurethe 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
21、converting the measurements of theresultant permanent impression to a hardness number.7. Apparatus7.1 Hardness Tester4, consisting of a load applicator, aKnoop indenter, and a microscope fitted with a movablemicrometer stage. The apparatus shall mechanically bring theindenter into contact with the t
22、est surface with negligibleimpact, apply the selected full load, maintain it for 18 6 0.5 s,and withdraw the indenter.7.2 Knoop IndenterThe Knoop indenter is a pyramidaldiamond with included longitudinal angles of 172 30 andincluded transverse angle of 130 0.NOTE 1The ratio of the long to the short
23、diagonal of the impressionis approximately 7:1; the ratio of the long diagonal to the depth ofpenetration is approximately 30:1.7.3 MicroscopeThe microscope shall have a filar microm-eter eyepiece and sufficient objectives to permit the measure-ment of the length of impression to within 61 %. Thespe
24、cimen shall be firmly supported on a movable micrometerstage attached to 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
25、the filar scale units ofthe eyepiece to millimetres.8.3 With a 25-g load 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 2
26、A suitable source of standard reference materials in thishardness range is available from the U.S. National Institute for Standardsand Technology.5By 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
27、 the participating hardness testers.9. Procedure9.1 Unless otherwise specified, make the hardness determi-nations at 23 6 2C 73.5 6 3.50F and 50 6 5 % relativehumidity after equilibrating the specimens under these condi-tions for at least 24 hours.9.2 Rigidly attach the specimen to the movable stage
28、 so thatthe surface to be measured is normal to the direction ofindentation. 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. Placeth
29、is area under the indenter by means of the movable microm-eter stage.NOTE 3If 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 a
30、pparatus to apply a load that permits thelength of identification to be read accurately 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 loa
31、d of 25 g and full load is applied, maintained for 186 0.5 seconds, and removed. For maximum accuracy, ensurethat the indenter has not penetrated the coating to a depth4A hardness tester meeting the apparatus requirements for this method is theTukon Microhardness Tester, available from the Wilson In
32、struments, Inc., Divisionof Instron, 100 Royall St., Canton, MA 02021.5Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.D1474/D1474M 132beyond three-fourths of the coating thickness. This is necessaryto el
33、iminate any major substrate effect on the hardness values.NOTE 4For maximum accuracy, care must be taken that the indenterdoes not penetrate the coating to a depth beyond three fourths of thecoating thickness. This is necessary to eliminate any major substrate effecton the hardness measurement.9.5 I
34、mmediately after the completion of the cycle, adjust themovable stage so that the indentation is in the field of themicroscope. Focus the microscope on the indentation so thatboth extremities of the long diagonal (that is, where the upperedges of the indentation just converge) are as sharp as possib
35、le.Measure the length of the long diagonal of the impression withthe filar micrometer eyepiece.NOTE 5Select a microscope 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 inf
36、ormationgiven in Note 1, and the measured film thickness at the placeof indentation, calculate the depth of indenter penetration. Ifthe depth of penetration exceeds three-fourths of the coatingthickness, the results may be influenced by substrate proximity.Consequently, repeat the test with specimen
37、s having a greaterfilm thickness or with a lighter load on the indenter.9.7 Since the applied load is not always the 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 = leng
38、th of long diagonal of indentation, mm, andCp= indenter constant = 7.028 102.9.8 The Knoop Hardness Numbers for a test load of one (1)gf and length of long diagonal of indentation from 1.0 to 200.9m are given in Table 1 of Test Method E384.10. Calculation10.1 Calculate the mean indentation length in
39、 filar units.10.2 Convert this mean indentation length to KHN bymeans of the appropriate tables supplied with the instrument.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 diagona
40、l of indentation, mm, andCp= indenter constant = 7.028 102.11. Report11.1 Report the following information:11.1.1 Mean 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 themeasure
41、ments made at the points of indentation,11.1.3 Specimen preparation and conditioning techniquesused,11.1.4 Mean and range of KHN values of the replicatepanels, and11.1.5 Substrate material of panel.12. Precision and Bias12.1 PrecisionOn the basis of an interlaboratory test ofthis method in which ope
42、rators in six laboratories tested sevencoated panels having a broad range of hardness, the within-laboratory coefficient of variation was found to be 3 % with 21degrees of freedom and the between-laboratories coefficient ofvariation 8 % with 30 degrees of freedom. Based upon thesecoefficients, the f
43、ollowing criteria should be used for judgingthe acceptability of results at the 95 % confidence level:12.1.1 RepeatabilityTwo results, each the mean of threedeterminations on a specimen, obtained by the same operatorshould be considered suspect if they differ by more than 9 % oftheir mean value.12.1
44、.2 ReproducibilityTwo results, each the mean of threedeterminations on a specimen, obtained by operators in differ-ent laboratories should be considered 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 u
45、sing the Knoop indenter willbe determined using data previously generated in round-robintesting.METHOD BPFUND INDENTATION HARDNESS13. Summary of Method13.1 This method consists of applying a load to the surfaceof a coating, by means of a transparent colorless quartz orsynthetic sapphire hemisphere h
46、aving a specified diameter, andconverting the measurement of the resultant observed impres-sion under load to a hardness number.14. Apparatus14.1 Hardness Testersconsisting of a load applicator, aPfund quartz or sapphire indenter, and a microscope with astage. The apparatus shall be constructed so a
47、s to permit theindenter to be brought manually into contact with the specimensurface with negligible impact.14.2 Pfund Indenter6The Pfund indenter (Fig. 1)isatransparent colorless quartz or synthetic sapphire hemispherewith a spherical radius of 3.18 mm 0.125 in. and a maximumspherical eccentricity
48、of 0.05 mm 0.002 in.14.3 MicroscopeThe microscope shall have a filar mi-crometer eyepiece and sufficient objectives to permit themeasurement of 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
49、60 6 0.5seconds.6A 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.D1474/D1474M 13315. Standardization15.1 Adjust the illumination in the microscope to givemaximum contrast when viewing an indentation.15.2 By means of 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, d
