1、Designation: D4541 091Standard Test Method forPull-Off Strength of Coatings Using Portable AdhesionTesters1This standard is issued under the fixed designation D4541; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEPractice D3980 was deleted from Section 2 in August 2010.1. Scope*1.1 This test method covers a procedure for evaluating thepull-o
3、ff strength (commonly referred to as adhesion) of acoating system from metal substrates. Pull-off strength ofcoatings from concrete is described in Test Method D7234. Thetest determines either the greatest perpendicular force (intension) that a surface area can bear before a plug of materialis detac
4、hed, or whether the surface remains intact at a pre-scribed force (pass/fail). Failure will occur along the weakestplane within the system comprised of the test fixture, adhesive,coating system, and substrate, and will be exposed by thefracture surface. This test method maximizes tensile stress asco
5、mpared to the shear stress applied by other methods, such asscratch or knife adhesion, and results may not be comparable.NOTE 1The procedure in this standard was developed for metalsubstrates, but may be appropriate for other rigid substrates such as plasticand wood. Factors such as loading rate and
6、 flexibility of the substrate mustbe addressed by the user/specifier.1.2 Pull-off strength measurements depend upon both ma-terial and instrumental parameters. Results obtained by eachtest method may give different results. Results should only beassessed for each test method and not be compared with
7、 otherinstruments. There are five instrument types, identified as TestMethods B-F. It is imperative to identify the test method usedwhen reporting results.NOTE 2Method A, which appeared in previous versions of thisstandard, has been eliminated as its main use is for testing on concretesubstrates (se
8、e Test Method D7234).1.3 This test method uses a class of apparatus known asportable pull-off adhesion testers.2They are capable of apply-ing a concentric load and counter load to a single surface sothat coatings can be tested even though only one side isaccessible. Measurements are limited by the s
9、trength of adhe-sion bonds between the loading fixture and the specimensurface or the cohesive strengths of the adhesive, coatinglayers, and substrate.1.4 This test can be destructive and spot repairs may benecessary.1.5 The values stated in MPa (inch-pound) units are to beregarded as the standard.
10、The values given in parentheses arefor information only.1.6 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-bilit
11、y of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D2651 Guide for Preparation of Metal Surfaces for Adhe-sive BondingD3933 Guide for Preparation of Aluminum Surfaces forStructural Adhesives Bonding (Phosphoric Acid Anodiz-ing)D7234 Test Method for Pull-Off Adhesion
12、Strength ofCoatings on Concrete Using Portable Pull-Off AdhesionTestersE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ANSI Standard:N512 Protective Coatings (Paints) for the Nuclear Industry42.3 ISO Standard:ISO 4624 Paints and VarnishPull-Off Tes
13、t for Adhesion43. Summary of Test Method3.1 The general pull-off test is performed by securing aloading fixture (dolly, stud) normal (perpendicular) to the1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct res
14、ponsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved Feb. 1, 2009. Published April 2009. Originallyapproved in 1993. Last previous edition approved in 2002 as D4541 02. DOI:10.1520/D4541-09E01.2The term adhesion tester may be somewhat of a misnomer, but its ad
15、option bytwo manufacturers and at least two patents indicates continued usage.3For 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 on
16、the ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
17、9428-2959, United States.surface of the coating with an adhesive. After the adhesive iscured, a testing apparatus is attached to the loading fixture andaligned to apply tension normal to the test surface. The forceapplied to the loading fixture is then gradually increased andmonitored until either a
18、 plug of material is detached, or aspecified value is reached. When a plug of material is detached,the exposed surface represents the plane of limiting strengthwithin the system. The nature of the failure is qualified inaccordance with the percent of adhesive and cohesive failures,and the actual int
19、erfaces and layers involved. The pull-offstrength is computed based on the maximum indicated load,the instrument calibration data, and the original surface areastressed. Pull-off strength results obtained using differentdevices may be different because the results depend oninstrumental parameters (s
20、ee Appendix X1).4. Significance and Use4.1 The pull-off strength of a coating is an importantperformance property that has been used in specifications. Thistest method serves as a means for uniformly preparing andtesting coated surfaces, and evaluating and reporting theresults. This test method is a
21、pplicable to any portable apparatusmeeting the basic requirements for determining the pull-offstrength of a coating.4.2 Variations in results obtained using different devices ordifferent substrates with the same coating are possible (seeSection 10). Therefore, it is recommended that the type ofappar
22、atus and the substrate be mutually agreed upon betweenthe interested parties.4.3 The purchaser or specifier shall designate a specific testmethod, that is, B, C, D, E, or F when calling out this standard.5. Apparatus5.1 Adhesion Tester, commercially available, or comparableapparatus specific example
23、s of which are listed in AnnexA1-Annex A5.5.1.1 Loading Fixtures, having a flat surface on one end thatcan be adhered to the coating and a means of attachment to thetester on the other end.5.1.2 Detaching Assembly (adhesion tester), having a cen-tral grip for engaging the fixture.5.1.3 Base, on the
24、detaching assembly, or an annular bearingring if needed for uniformly pressing against the coatingsurface around the fixture either directly, or by way of anintermediate bearing ring. A means of aligning the base isneeded so that the resultant force is normal to the surface.5.1.4 Means of moving the
25、 grip away from the base in assmooth and continuous a manner as possible so that a torsionfree, co-axial (opposing pull of the grip and push of the basealong the same axis) force results between them.5.1.5 Timer, or means of limiting the loading rate to 1 MPa/s(150 psi/s) or less for a 20 mm loading
26、 fixture so that the testis completed in about 100 s or less. A timer is the minimumequipment when used by the operator along with the forceindicator in 5.1.6.5.1.6 Force Indicator and Calibration Information, fordetermining the actual force delivered to the loading fixture.5.2 Solvent, or other mea
27、ns for cleaning the loading fixturesurface. Finger prints, moisture, and oxides tend to be theprimary contaminants.5.3 Fine Sandpaper, or other means of cleaning the coatingthat will not alter its integrity by chemical or solvent attack. Ifany light sanding is anticipated, choose only a very fine gr
28、adeabrasive (400 grit or finer) that will not introduce flaws or leavea residue.5.4 Adhesive5, for securing the fixture to the coating thatdoes not affect the coating properties. Two component epoxiesand acrylics have been found to be the most versatile.5.5 Magnetic or Mechanical Clamps, if needed,
29、for holdingthe fixture in place while the adhesive cures.5.6 Cotton Swabs, or other means for removing excessadhesive and defining the adhered area. Any method forremoving excess adhesive that damages the surface, such asscoring (see 6.7), must generally be avoided since inducedsurface flaws may cau
30、se premature failure of the coating.5.7 Circular Hole Cutter (optional), to score through to thesubstrate around the loading fixture.6. Test Preparation6.1 The method for selecting the coating sites to be preparedfor testing depends upon the objectives of the test andagreements between the contracti
31、ng parties. There are, how-ever, a few physical restrictions imposed by the general methodand apparatus. The following requirements apply to all sites:6.1.1 The selected test area must be a flat surface largeenough to accommodate the specified number of replicate tests.The surface may have any orien
32、tation with reference togravitational pull. Each test site must be separated by at leastthe distance needed to accommodate the detaching apparatus.The size of a test site is essentially that of the secured loadingfixture. At least three replications are usually required in orderto statistically char
33、acterize the test area.6.1.2 The selected test areas must also have enough perpen-dicular and radial clearance to accommodate the apparatus, beflat enough to permit alignment, and be rigid enough to supportthe counter force. It should be noted that measurements closeto an edge may not be representat
34、ive of the coating as a whole.6.2 Since the rigidity of the substrate affects pull-offstrength results and is not a controllable test variable in fieldmeasurements, some knowledge of the substrate thickness andcomposition should be reported for subsequent analysis orlaboratory comparisons. For examp
35、le, steel substrate of lessthan 3.2 mm (18 in.) thickness usually reduces pull-off strengthresults compared to 6.4 mm (14-in.) thick steel substrates.6.3 Subject to the requirements of 6.1, select representativetest areas and clean the surfaces in a manner that will not affectintegrity of the coatin
36、g or leave a residue. To reduce the risk ofglue failures, the surface of the coating can be lightly abradedto promote adhesion of the adhesive to the surface. If thesurface is abraded, care must be taken to prevent damage to thecoating or significant loss of coating thickness. Solvent cleanthe area
37、to remove particulates after abrading. Select a solventthat does not compromise the integrity of the coating.5Scotch Weld 420, available from 3M, Adhesives, Coatings and Sealers Div.,3M Center, St. Paul, MN 55144, was used in the round robin.D4541 09126.4 Clean the loading fixture surface as indicat
38、ed by theapparatus manufacturer. Failures at the fixture-adhesive inter-face can often be avoided by treating the fixture surfaces inaccordance with an appropriate ASTM standard practice forpreparing metal surfaces for adhesive bonding.NOTE 3Guides D2651 and D3933 are typical of well-proven methodsf
39、or improving adhesive bond strengths to metal surfaces.6.5 Prepare the adhesive in accordance with the adhesivemanufacturers recommendations. Apply the adhesive to thefixture or the surface to be tested, or both, using a methodrecommended by the adhesive manufacturer. Be certain toapply the adhesive
40、 across the entire surface. Position fixture onthe surface to be tested. Carefully remove the excess adhesivefrom around the fixture. (WarningMovement, especiallytwisting, can cause tiny bubbles to coalesce into large holidaysthat constitute stress discontinuities during testing.)NOTE 4Adding about
41、1 percent of #5 glass beads to the adhesiveassists in even alignment of the test fixture to the surface.6.6 Based on the adhesive manufacturers recommendationsand the anticipated environmental conditions, allow enoughtime for the adhesive to set up and reach the recommendedcure. During the adhesive
42、set and early cure stage, a constantcontact pressure should be maintained on the fixture. Magneticor mechanical clamping systems work well, but systemsrelying on tack, such as masking tape, should be used with careto ensure that they do not relax with time and allow air tointrude between the fixture
43、 and the test area.6.7 Scoring around the fixture violates the fundamental insitu test criterion that an unaltered coating be tested. If scoringaround the test surface is employed, extreme care is required toprevent micro-cracking in the coating, since such cracks maycause reduced adhesion values. S
44、cored samples constitute adifferent test, and this procedure should be clearly reportedwith the results. Scoring is only recommended for thicker-filmcoatings, that is, thicknesses greater than 500 m (20 mils),reinforced coatings and elastomeric coatings. Scoring, if per-formed, shall be done in a ma
45、nner that ensures the cut is madenormal to the coating surface and in a manner that does nottwist or torque the test area and minimizes heat generated andedge damage or microcracks to the coating and the substrate.For thick coatings it is recommended to cool the coating andsubstrate during the cutti
46、ng process with water lubrication.NOTE 5A template made from plywood with a hole of the same sizedrilled through it has been found to be an effective method to limitsideways movement of the drill bit.6.8 Note the approximate temperature and relative humidityduring the time of test.7. Test Procedure7
47、.1 Test Methods:7.1.1 Test Method A (discontinued).7.1.2 Test Method B Fixed Alignment Adhesion TesterType II:7.1.2.1 Operate the instrument in accordance with AnnexA1.7.1.3 Test Method C Self-Alignment Adhesion Tester TypeIII:7.1.3.1 Operate the instrument in accordance with AnnexA2.7.1.4 Test Meth
48、od D Self-Alignment Adhesion Tester TypeIV:7.1.4.1 Operate the instrument in accordance with AnnexA3.7.1.5 Test Method E Self-Alignment Adhesion Tester TypeV:7.1.5.1 Operate the instrument in accordance with AnnexA4.7.1.6 Test Method F Self-Alignment Adhesion Tester TypeVI:7.1.6.1 Operate the instru
49、ment in accordance with AnnexA5.7.2 Select an adhesion-tester with a detaching assemblyhaving a force calibration spanning the range of expectedvalues along with its compatible loading fixture. Mid-rangemeasurements are usually the best, but read the manufacturersoperating instructions before proceeding.7.3 If a bearing ring or comparable device (5.1.3)istobeused, place it concentrically around the loading fixture on thecoating surface. If shims are required when a bearing ring isemployed, place them between the tester base and bearing ringrather than on t
