1、Designation:D279493(Reapproved 2010)Standard Test Method forResistance of Organic Coatings to the Effects of RapidDeformation(Impact)1This standard is issued under the fixed designation D2794;the number immediately following the designation indicates the year oforiginal adoption or,in the case of re
2、vision,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 Department of Defense.1.Scope1.1 This test method covers
3、 a procedure for rapidly deform-ing by impact a coating film and its substrate and for evaluatingthe effect of such deformation.1.2 This test method should be restricted to testing in onlyone laboratory when numerical values are used because of thepoor reproducibility of the method.Interlaboratory a
4、greementis improved when ranking is used in place of numerical values.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standar
5、d 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:2D60
6、9 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 PanelsD1186 Test Methods for Nondestructive Measurement ofDry Film Thick
7、ness of Nonmagnetic Coatings Applied toa Ferrous Base(Withdrawn 2006)33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 impact resistance,of a coating,nthe number ofinch-pounds(kilogram-metres)required to produce cracking inthe deformed coating.4.Summary of Test Method4.1 The org
8、anic coatings under test are applied to suitablethin metal panels.After the coatings have cured,a standardweight is dropped a distance so as to strike an indenter thatdeforms the coating and the substrate.The indentation can beeither an intrusion or an extrusion.By gradually increasing thedistance t
9、he weight drops,the point at which failure usuallyoccurs can be determined.Films generally fail by cracking,which is made more visible by the use of a magnifier,by theapplication of a copper sulfate(CuSO4)solution on steel,or bythe use of a pin hole detector.5.Significance and Use5.1 Coatings attach
10、ed to substrates are subjected to damag-ing impacts during the manufacture of articles and their use inservice.In its use over many years,this test method for impactresistance has been found to be useful in predicting theperformance of organic coatings for their ability to resistcracking caused by i
11、mpacts.6.Apparatus6.1 Tester,consisting of a vertical tube to guide a cylindricalweight that is dropped on a punch resting on the test panel.6.1.1 Guide Tube,24 to 48 in.(0.6 to 1.2 m)long mountedvertically in a base plate.A slot is cut lengthwise on one sideof the tube to act as a guide for a cylin
12、drical weight that fitsinside the tube.Graduations are marked in inch-pounds alongthe slot.The base is constructed so that a thin flat panel can beinserted at 2 in.(50 mm)below the tube.6.1.2 Weight,metal cylinder,made to fit inside the guidetube.Apin is fitted into one side of the weight to act as
13、a guideby riding in the slot of the tube and to serve as a handle bywhich the weight can be raised and released and serve as theindicator of inch-pounds(kilogram-metres).1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is t
14、he direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Dec.1,2010.Published December 2010.Originallyapproved in 1969.Last previous edition approved in 2004 as D2794 93(2004).DOI:10.1520/D2794-93R10.2For referenced ASTM standards,visit th
15、e 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM Intern
16、ational,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 IndenterA steel punch with a hemispherical headhaving a diameter of either 0.500 in.(12.7 mm)or 0.625 in.(15.9 mm).The head rests on the test panel and the punch isheld vertically by a guide ring.6.3 Panel SupportA steel fixture with a 0.64-in.(16.3-mm)diameter cylindrical hole centered under the indenter forsupporting the test panel.6.4 Magnifier.6.5 Pin Hole Detector.7.Reagents7.1 An acidified copper s
