1、Designation: D 5178 98 (Reapproved 2008)Standard Test Method forMar Resistance of Organic Coatings1This standard is issued under the fixed designation D 5178; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. 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 determination of the marresistance on smooth, flat surfaces. Results are expressed interms of force-to
3、-mar films of organic coatings such as paint,varnish, and lacquer when applied to smooth, flat planar panelsurfaces.1.2 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 onlya
4、nd are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, 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 limitatio
5、ns prior to use.2. Referenced Documents2.1 ASTM Standards:2D 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating ProductsD 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test Pan
6、elsD 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base3D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Noncond
7、uctive CoatingsApplied toa Nonferrous Metal Base3D 2691 Method for Microscopical Measurement of DryFilm Thickness of Coatings on Wood Products33. Terminology3.1 Definitions:3.1.1 mar resistance, nthe ability of a coating to resistdamage caused by light abrasion. As just defined, it is aresistance of
8、 the surface of the coating to permanent deforma-tion, resulting from the application of a dynamic mechanicalforce.4. Summary of Test Method4.1 The materials under test are applied at uniform thicknessto flat panels of uniform surface texture. After drying/curing,the mar resistance is determined by
9、pushing the panels beneatha rounded stylus or loop that is loaded in increasing amountsuntil the coating is marred.5. Significance and Use5.1 In some situations, marring of coatings applied tosubstrates under typical use conditions is unacceptable. Thistest method has been found useful in differenti
10、ating the degreeof marring of coatings on substrates. It is most useful inproviding relative ratings for a series of coated panels exhib-iting significant differences in marring.5.2 In a limited laboratory study, meaningful mar resultswere impossible when powder coatings were tested. The marmarking,
11、 that is, scratches, became less perceptible with time.Therefore, powder coatings may not be applicable coatings forthis test method.6. Apparatus6.1 Application Equipment, as described in Practices D 823.6.2 Film-Thickness Measuring Apparatus, as described inTest Methods D 1005, D 1186, D 1400,orD 2
12、691.6.3 Balanced Beam Scrape Adhesion and Mar Tester (Fig.1 and Fig. 2), consisting of a balanced beam to which issecured a platform for supporting weights, and a rod at anangle of 45 that holds the scraping loop. The rod shall be setso that the scraping loop contacts test surfaces directly belowthe
13、 weights. The loop shall be116-in. (1.6 mm) diameter rod,bent into a “U” shape with an outside radius of 0.128 6 0.002in. (3.25 6 0.05 mm) and hardened to Rockwell HRC 56 to 58,and shall be a smooth finish. The loop can be either chromiumplated, nickel plated, or heat treated polished steel as agree
14、dupon between the purchaser and the supplier. These testers are1This 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 edit
15、ion approved July 1, 2008. Published July 2008. Originally approvedin 1991. Last previous edition approved in 2002 D 5178 98 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume inform
16、ation, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.adjustable to accommodate flat, metallic, and nonmetallicspecimens to 0.5-in. (12-mm) thick and 4 to 16
17、 in. (100 to 400mm) wide and long; the specimen should be at least12-in.(12-mm) wide.7. Preparation of Specimens7.1 Apply the materials under test to panels of the compo-sition and surface condition on which it is desired to determinemar resistance of the coating. The panel material (7.1.1),surface
18、preparation, thickness, and number of coats shall bespecified or agreed upon between the seller and the purchaser.Apply coatings and air dry or bake under conditions ofhumidity and temperature mutually agreeable to the seller andthe purchaser.7.1.1 The surface of the coating must be hard enough tore
19、sist damage by the scraping loop at a load agreed uponbetween the producer and the user. If no panel material isspecified, use 0.032-in. (0.8-mm) cold-rolled carbon steelprepared in accordance with Methods B or C of Practice D 609.8. Conditioning and Number of Tests8.1 Condition the test panels for
20、at least 48 h at 23 6 2C(73.5 6 3.5F) and 50 6 5 % relative humidity, and test in thesame environment, or immediately on removal therefrom,unless otherwise specified or agreed upon by the seller and thepurchaser. Test at least two replicate specimens of eachmaterial.9. Procedure9.1 In preparation fo
21、r using the apparatus, ensure that it isreasonably level and place it so that the weight holder is towardthe operator. This places the beam release on the operatorsright and allows freedom to move the test specimen manuallyunder the weighted scraping element (loop). Insert the loopinto the holder as
22、 far as it will go and tighten the clampingscrew. Adjust the main bearing support so that the beam isbalanced in the horizontal plane when the loop is just touchingthe specimen surface. The alignment of the beam should besuch that the end of the loop is over the midline of the movabletable.9.2 Raise
23、 the beam and lock it in the raised position. Wipethe loop with a clean cloth or chamois. Locate the specimen onthe sliding platform against the stop so that the specimen canbe moved away from the operator and there is an area at least3 in. (75 mm) long by12 in. (12 mm) wide on the sampleparallel to
24、 the horizontal plane through the beam. Placeweights on the weight support using an initial amount that isestimated to be appropriate for the particular coating. Releasethe beam and carefully lower it until the loop rests on thecoated test specimen and the full load is applied, then slowlypush the s
25、liding platform away from the operator at a rate of14in. (6 mm)/s for a distance of at least 3 in. (75 mm). If thecoating is marred, continue the testing using successivelysmaller loads (0.5-kg increments) until the coating is notmarred. If the coating is not marred by the initial scrape,continue th
26、e test using successively larger loads (0.5-kgincrements) until the coating is marred or until the maximumload of 10 kg has been applied. Use a new area of the testsurface each time a scrape is made.9.3 When the critical load has been approximately located,repeat the test five times at each of three
27、 loadings: above,below and at the load determined in the first trial. Applydifferent loads in random fashion so that all scrapes at one loadare not made in succession or on one panel.9.3.1 Periodically examine the loop to ensure that theoriginal smooth surface is intact. If the contacting surface is
28、worn, reverse the loop. When both sides are worn, replace witha new loop.9.4 For each applied load, tabulate the number of times thecoating was marred.10. Report10.1 Report the following information:10.1.1 Load in kilograms at the mar failure end point,10.1.2 Panel material and surface preparation,1
29、0.1.3 “U” shape loop surface finish,10.1.4 Dry-film thickness, and10.1.5 Any deviation from the specified procedure.11. Precision11.1 PrecisionIf sufficient cooperators can be obtained,an interlaboratory study will be conducted to establish preci-sion.11.2 BiasNo information can be provided on the b
30、ias ofthis test method for measuring mar because no material havingan accepted reference value is available.FIG. 1 Balanced Beam Scrape Adhesion and Mar TesterFIG. 2 Balanced Beam Scrape Adhesion and Mar TesterD 5178 98 (2008)212. Keywords12.1 balanced beam scrape adhesion and mar tester; bal-anced
31、beam tester; coatings; mar or organic mar resistanceASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rig
32、hts, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for
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34、 you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 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 the ASTM website(www.astm.org).D 5178 98 (2008)3
