1、Designation: B578 87 (Reapproved 2015)Standard Test Method forMicrohardness of Electroplated Coatings1This standard is issued under the fixed designation B578; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript 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. Scope1.1 This test method covers the determination o
3、f the hard-ness of metallic coatings upon various substrates. The mea-surements are made with the Knoop indenter under a test loadof 0.245 N (25 gf) or 0.981 N (100 gf).1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility o
4、f 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:E384 Test Method for Knoop and Vickers Hardness ofMaterials23. Special Requirements3.1 In addition to th
5、e requirements listed herein, the testmethod shall be performed in accordance with Test MethodE384.3.1.1 The measurement shall be made on the cross sectionwith the long diagonal of the indentation parallel to thesubstrate using a Knoop indenter.NOTE 1When a nondestructive test is necessary, the meas
6、urementmay be made normal to the surface provided that the whole of theindentation is clearly delineated in the field of the microscope at themagnification specified in Test Method E384, and the coating thickness isat least 0.7 that of the long diagonal. The outlines of the indentation mustbe sharp
7、and undistorted by any mechanical effects resulting from thethinness of the coating such as “butterfly” fractures, etc. Values obtainedfrom measurements made normal to the electroplated surface may not beequivalent to those obtained on microsections and are not, therefore,reportable according to Sec
8、tion 6.3.1.2 The thickness of the coating shall be at least 38 m forsoft coatings such as gold, copper, and silver, and 25 m forhard coatings such as nickel, cobalt, iron, and hard gold. Thisis approximately equivalent to 0.6 times the length of the longKnoop diagonal.3.1.3 Make the indentation near
9、 the center of the crosssection of the coating.3.2 No single test load is applicable to all coatings. Use aload of 0.245 N for soft coatings (from 50 to 300 HK) and aload of 0.981 N for hard coatings (greater than 300 HK).3.2.1 A load of less than 0.245 N is not recommended.However, when the length
10、of the diagonal is great enough at aload of 0.245 N, which may occur for very soft coatings suchas tin and indium, a lighter load or a lower magnification shallbe specified provided the requirements of 3.3 are met. Whentesting extremely hard coatings, a load greater than 0.981 Nmay be used provided
11、this is specified in the purchase order.The Knoop hardness number decreases appreciably with loadsfrom 0.245 N to 0.981 N especially for the higher hardnessnumbers.3.3 Measure the length of the long diagonal to within 0.25m or 0.4 %, whichever is larger, at the magnification specifiedin Test Method
12、E384.3.4 When readings are taken in a direction parallel to thesubstrate, space them from each other by at least the length ofthe long diagonal. When two readings are taken in the directionof the short axis, separate them by at least the length of thediagonal perpendicular to the substrate (short di
13、agonal). Insuch cases, the distance from the substrate and from the outersurface of the coating to an edge of the indentation shall be atleast the width of the short diagonal.3.5 If the electroplated coating is cracked, or if cracks or“butterfly” markings (see 7.2 of Test Method E384) appearwhen the
14、 indentation load is applied or removed, the hardnessmeasurement is invalid.4. Preparation of Test Specimen4.1 Overplate the specimen to a thickness of at least 12 mwith a metal of a contrasting color whose hardness approxi-mates that of the coating.1This test method is under the jurisdiction ofASTM
15、 Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 onTest Methods.Current edition approved March 1, 2015. Published April 2015. Originallyapproved in 1973. Last previous edition approved in 2009 as B578 87 (2009).DOI: 10.1520/B0578-87R15.2For ref
16、erenced 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 Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
17、t Conshohocken, PA 19428-2959. United States14.2 Cut out a section of the specimen approximately per-pendicular to the electroplated coating.4.3 Mount and polish the section as described in TestMethod E384.NOTE 2Procedures 4.1 and 4.2 are interchangeable at the discretion ofthe operator.Alight etch
18、following polishing may remove significant workhardening.4.4 When the electrodeposit is a metal which may alloy withthe basis metal (for example, indium over copper or copperalloys), or if the deposit has a low transformation temperature(such as nickel-phosphorus alloys), a low-temperature mount-ing
19、 procedure shall be used.5. Procedure5.1 Insert the mounted specimen into the testing machine sothat the test surface is parallel to the long axis of the indenter,and measure the hardness in accordance with the manufactur-ers instructions and in accordance with Test Method E384,Section A.6. Report6.
20、1 Test results shall be based on at least five measurements,and the report shall include the following statistics:6.1.1 The range, that is, the difference, in hardness units,between the highest and lowest values.6.1.2 The average (arithmetic mean):x 5(x/n (1)6.1.3 The estimated standard deviation:s
21、5 =(x 2 x!2/n 2 1! or =n(x22 (x!2/nn 2 1! (2)6.1.4 The coefficient of variation: 5sx(3)where, in 6.1.2 6.1.4:s = the standard deviation,x = an individual value,x = arithmetic mean of the set of individual values,n = the number of measurements,x2= the sum of the squares of all of the individual value
22、s,(x)2= the square of the total of the individual values, and = the coefficient of variation.6.2 Report the hardness as a Knoop hardness number (HK),and indicate the load by subscript notation expressed as theforce, in newtons, divided by 0.00981 (a number equal to thatwhich is obtained when the tes
23、t force is expressed in grams-force). For example: 410 HK100,30HK50, 200 HK25.NOTE 3The International Organization for Standardization TechnicalCommittee 17 on Steel has agreed that the formula for calculation and thesystem of designation for hardness shall be such that the numerical valueof the har
24、dness number remains unaffected by the introduction of the SIunit of force, the newton, in place of the old unit, kgf (or gf).7. Precision and Bias7.1 PrecisionAn interlaboratory comparison program isnow in progress which when completed will be the basis of astatement on precision.7.2 BiasThere is n
25、o basis for defining the bias of this testmethod.7.3 Reference hardness specimens of electroformed nickelalong with certified hardness readings as found by the NationalInstitute of Standards and Technology (NIST) are currentlyavailable.38. Test Coupons8.1 If specifically permitted by the governing s
26、pecificationor the party requesting the test, test coupons may be used whenthe production parts have insufficient electroplating thicknessfor measurement. The values obtained may not reflect the“true” hardness of the thin coatings on production parts.However, the values may be useful when they corre
27、late withother coating properties such as wear resistance. The test mayserve as a useful tool for electroplating bath control, particu-larly in the case of coatings such as gold, for which thehardness will be sensitive to the composition of the bath andother electroplating variables. The electroplat
28、ing conditions fortest coupons such as current density, temperature, agitation,and solution composition, shall be kept as close as possible tothose employed on production parts in the plating processunder test.ASTM International takes no position respecting the validity of any patent rights asserted
29、 in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the
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31、areful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Internati
32、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through th
33、e ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.B578 87 (2015)2
