1、Designation: D 5178 98 (Reapproved 2002)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 (e) 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-t
3、o-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 the standard. The values given in parentheses are forinformation only.1.3 This standard does not purport to address all
4、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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 609 Practice for Prep
5、aration of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating Products2D 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test Panels2D 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings
6、 Using Micrometers2D 1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base2D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive Coatings Applied toa Nonferrous Metal Base2D 2691 Test Methods for Micro
7、scopical Measurement ofDry Film Thickness of Coatings on Wood Products33. Terminology3.1 Definitions:3.1.1 mar resistancethe ability of a coating to resistdamage caused by light abrasion. As just defined, it is aresistance of the surface of the coating to permanent deforma-tion, resulting from the a
8、pplication 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 pushing the panels beneatha rounded stylus or loop that is loaded in increa
9、sing 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 differentiating the degreeof marring of coatings on substrates. It is most useful inp
10、roviding 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, that is, scratches, became less perceptible with time.Therefore, powder co
11、atings 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, or D 2691.6.3 Balanced Beam Scrape Adhesion and Mar Tester (Fig.1 and Fig. 2),
12、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 weights. The loop shall be116-in. (1.6 mm) diameter rod,bent into a “U”
13、shape with an outside radius of 0.128 60.002in. (3.25 60.05 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 agreedupon between the purchaser and the supplier. These testers areadjustable t
14、o accommodate flat, metallic, and nonmetallicspecimens to 0.5-in. (12-mm) thick and 4 to 16 in. (100 to 4001This test method is under the jurisdiction of ASTM Committee D01 on Paintsand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical P
15、roperties of Applied Paint Films.Current edition approved Feb. 10, 1998. Published September 1998. Originallypublished as D 5178 91. Last previous edition D 5178 91.2Annual Book of ASTM Standards, Vol 06.01.3Discontinued; see 1992 Annual Book of ASTM Standards, Vol 06.02.1Copyright ASTM Internationa
16、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.mm) 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 dete
17、rminemar resistance of the coating. The panel material (7.1.1),surface 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 and
18、the purchaser.7.1.1 The surface of the coating must be hard enough toresist 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 60
19、9.8. Conditioning and Number of Tests8.1 Condition the test panels for at least 48 h at 23 62C(73.5 63.5F) and 50 65 % 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 r
20、eplicate specimens of eachmaterial.9. Procedure9.1 In preparation for 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
21、 weighted scraping element (loop). Insert the loopinto the holder as 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 t
22、he end of the loop is over the midline of the movabletable.9.2 Raise 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 le
23、ast3 in. (75 mm) long by12 in. (12 mm) wide on the sampleparallel to 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 thecoat
24、ed test specimen and the full load is applied, then slowlypush the sliding 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 notma
25、rred. If the coating is not marred by the initial scrape,continue the 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 be
26、en approximately located,repeat the test five times at each of three 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 tha
27、t theoriginal smooth surface is intact. If the contacting surface isworn, 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 m
28、ar failure end point,10.1.2 Panel material and surface preparation,10.1.3 “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 e
29、stablish preci-sion.11.2 BiasNo information can be provided on the bias ofthis test method for measuring mar because no material havingan accepted reference value is available.12. Keywords12.1 balanced beam scrape adhesion and mar tester; bal-anced beam tester; coatings; mar or organic mar resistanc
30、eFIG. 1 Balanced Beam Scrape Adhesion and Mar TesterFIG. 2 Balanced Beam Scrape Adhesion and Mar TesterD 51782ASTM 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
31、 that determination of the validity of any such patent rights, 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 rea
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33、u feel that your comments have not received a fair hearing 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 51783
