ASTM_D_7187_-_15.pdf

Designation:D718715Standard Test Method forMeasuring Mechanistic Aspects of Scratch/Mar Behavior ofPaint Coatings by Nanoscratching1This standard is issued under the fixed designation D7187;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.1.Scope1.1 This test method covers the nanoscratch method fordetermining the resistance of paint coatings on smooth flatsurfaces to scratch/mar.1.2 Previous methods used in scratch/mar evaluation firstphysically scratch or mar a samples surface with multiplecontact cutting,and then use visual inspection to assign aranking.It has been recognized that loss of appearance ismainly due to surface damages created.The philosophy of thismethod is to quantitatively and objectively measure scratch/mar behavior by making the evaluation process two steps withemphasis on surface damages.Step one is to find the relation-ship between damage shape and size and external input(suchas forces,contact geometry,and deformation).Step two is torelate damage shape and size to visual loss of luster.The firststep is covered by this method;in addition,a survey in theappendix provides an example of an experiment to relate thedamage to the change in luster.1.3 There are three elementary deformation mechanisms:elastic deformation,plastic deformation and fracture;only thelatter two both contribute significantly to mar.This methodevaluates scratch/mar based on the latter two damage mecha-nisms.1.4 Although this standard was developed for paintcoatings,it can also be applied to other types of similarpolymer-based coatings,for example,lacquers,varnishes,glazes and other decorative and protective layers deposited onhard substrates.1.5 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety problems,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 of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint,Varnish,Conversion Coatings,andRelated Coating ProductsD823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1044 Test Method for Resistance of Transparent Plastics toSurface AbrasionD3363 Test Method for Film Hardness by Pencil TestD3924 Specification for Environment for Conditioning andTesting Paint,Varnish,Lacquer,and Related MaterialsD5178 Test Method for Mar Resistance of Organic CoatingsD6037 Test Methods for Dry Abrasion Mar Resistance ofHigh Gloss CoatingsD6279 Test Method for Rub Abrasion Mar Resistance ofHigh Gloss CoatingsD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic,Nonconductive Coat-ings Applied to Non-Ferrous MetalsG171 Test Method for Scratch Hardness of Materials Usinga Diamond Stylus3.Summary of Test Method3.1 This test method is based on representative samples ofthe paint film being scratched using a nanoscratch instrument.From information received during a scratch test,values forplastic resistance and fracture resistance can be determined.3.2 From these values of plastic resistance and fractureresistance,the mechanistic aspects of scratch/mar behavior ofthe coating can be subsequently compared.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Feb.1,2015.Published April 2015.Originallyapproved in 2005.Last previous edition approved in 2010 as D7187 10.DOI:10.1520/D7187-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For ASTM 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.Significance and Use4.1 This test attempts to address two major drawbacks inexisting mar tests such as Test Methods D1044,D3363,D5178,D6037,and D6279,namely:4.1.1 Measured damage is caused by hundreds of contactswith differing contact geometries making it difficult or impos-sible for mechanical quantities(force,displacement)at thecontact points to be reliably determined.4.1.2 The damage is evaluated using subjective visualassessments,which provide only a qualitative sense of wearwit