ASTM_G_171_-_03_2009e2.pdf

Designation:G17103(Reapproved 2009)2Standard Test Method forScratch Hardness of Materials Using a Diamond Stylus1This standard is issued under the fixed designation G171;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEDeleted erroneous reference in 8.4 editorially in May 2009.2NOTEReference to specific brand of scratch tester was removed from Appendix X1 editorially in September 2009.1.Scope1.1 This test method covers laboratory procedures for de-termining the scratch hardness of the surfaces of solid materi-als.Within certain limitations,as described in this guide,thistest method is applicable to metals,ceramics,polymers,andcoated surfaces.The scratch hardness test,as described herein,is not intended to be used as a means to determine coatingadhesion,nor is it intended for use with other than specifichemispherically-tipped,conical styli.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous materials,operations,and equipment.This standard does not purport toaddress all of the safety concerns,if any,associated with itsuse.It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2G40 Terminology Relating to Wear and ErosionG117 Guide for Calculating and Reporting Measures ofPrecision Using Data from Interlaboratory Wear or Ero-sion Tests3.Terminology3.1 DefinitionsFor definitions of terms applicable to thisstandard see Terminology G40.3.2 Definitions of Terms Specific to This Standard:3.2.1 scratch hardness number,na quantity,expressed inunits of force per unit area,that characterizes the resistance ofa solid surface to penetration by a moving stylus of given tipradius under a constant normal force and speed;namely,HSP5k Pw2where:HSP=scratch hardness number,k=a geometrical constant,P=applied normal force,andw=scratch width.NOTE1The constant k may be chosen to include conversion factorsfor expressing HSPin units of GPa.For HSPin GPa,P in grams-force,andw in m,k=24.98.3.2.2 scratching force,nthe force that opposes relativemotion between a moving stylus and the surface that is beingscratched by that stylus,and which is perpendicular to thenormal force exerted by the stylus.3.2.3 stylus drag coeffcient,nin scratch testing,the di-mensionless ratio of the scratching force to the normal forceapplied to the stylus;namely,Dsc5FscrPwhere:Dsc=stylus drag coefficient,Fscr=scratching force,andP=normal force.4.Summary of Test Method4.1 This test involves producing a scratch in a solid surfaceby moving a diamond stylus of specified geometry along aspecified path under a constant normal force and with aconstant speed.The average width of the scratch is measured,and that value is used to compute the scratch hardness numberin units of pressure.4.2 As an option,the scratching force may be measuredduring this test and used to compute a stylus drag coefficient,which is a dimensionless measure of the resistance of the testsurface to deformation by a tangentially-moving stylus.1This test method is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.30 on AbrasiveWear.Current edition approved May 1,2009.Published May 2009.Originallyapproved in 2003.Last previous edition approved in 2003 as G17103.DOI:10.1520/G0171-03R09E02.2For 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 Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.3 This test is usually conducted under unlubricated con-ditions and at room temperature;however,it is possible toconduct scratch hardness tests under lubricated and elevatedtemperature conditions.The provisions of this standard allowtesting under both conditions provided that requirements forvalid scratch hardness testing are met and that the testingconditions are fully reported.4.4 Effects of moisture in the air and other ambient atmo-spheric conditions may affect results depending on the sensi-tivity of the test material to the environment.If such effects areeither expected or observed during the course of testing,precautions to control the surrounding atmosphere and todocument the relative humidity level should be taken andreported.5.Significance and Use5.1 This test method is intended to measure the resistance ofsolid surfaces to permanent deformation under the action of asingle point(stylus tip)