ASTM_D_968_-_15.pdf

Designation:D96815Standard Test Methods forAbrasion Resistance of Organic Coatings by FallingAbrasive1This standard is issued under the fixed designation D968;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 These test methods cover the determination of theresistance of organic coatings to abrasion produced by abrasivefalling onto coatings applied to a plane rigid surface,such as ametal or glass panel.1.2 Two test methods based on different abrasives arecovered as follows:SectionsMethod AFalling Sand Abrasion Test6 13Method BFalling Silicon Carbide Abrasion Test14 211.3 These methods should be restricted to testing in onlyone laboratory when numerical values are used because of thepoor reproducibility of the methods(see 13.1.2 and 21.1.2).Interlaboratory agreement is improved significantly when rank-ing is used in place of numerical values.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 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 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 Thick-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 MetalsE11 Specification for Woven Wire Test Sieve Cloth and TestSieves2.2 Other Standards:ANSI B74.12 Specifications for the Size of Abrasive Grain Grinding Wheels,Polishing and General IndustrialUses3FEPA Standard 42-2:2006 Grains of Fused AluminumOxide,Silicon Carbide and other Abrasive Materials forBonded Abrasives and for General Applications Mi-crogrits F230 to F200043.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 abrasion resistance,nthe amount of abrasive re-quired to wear through a unit film thickness of the coating.4.Summary of Test Method4.1 Abrasive is allowed to fall from a specified heightthrough a guide tube onto a coated panel until the substratebecomes visible.The amount of abrasive per unit film thick-ness is reported as the abrasion resistance of the coating on thepanel.Silica sand or silicon carbide may be used,as specified.5.Significance and Use5.1 Silica sand produces a slower rate of abrasion fororganic coatings than that provided by silicon carbide.Forsome types of coatings,it may also provide greater differen-tiation.5.2 The abrasion resistance scales produced by the twomethods differ,but the methods provide approximately thesame rankings of coatings for abrasion resistance.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 Properties of Applied PaintFilms.Current edition approved June 1,2015.Published June 2015.Originallyapproved in 1948.Last previous edition approved in 2010 as D968 05(2010).DOI:10.1520/D0968-15.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.4Available from Federation of European Producers of Abrasives(FEPA),20,av.Reille,Paris,F-75014,www.fepa-abrasives.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.3 Each of the methods has been found useful for rating theabrasion resistance of specific types of coatings.For exampleMethod A(falling sand)has been used for rating floor coatingswhile Method B(falling silicon carbide)has been used forrating coatings for ship decks.METHOD AFALLING SAND ABRASION TEST56.Apparatus and Materials6.1 Abrasion Tester,as illustrated in Fig.1 and Fig.2.Agatefor starting the flow of abrasive is located near the top of theguide tube.It consists of a metal disk inserted into a slit in theside of the guide tube with a collar covering the slit.The guidetube shall be firmly supported in a vertical position over asuitable receptacle,which shall contain a support for holdingthe coated panel at an angle of 45 to the vertical.The openingof the tube is di