ASTM B571-97e1
(Practice)Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
Standard Practice for Qualitative Adhesion Testing of Metallic Coatings
SCOPE
1.1 This practice describes simple, qualitative tests for evaluating the adhesion of metallic coatings on various substances.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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e1
Designation: B 571 – 97
Standard Practice for
Qualitative Adhesion Testing of Metallic Coatings
This standard is issued under the fixed designation B 571; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Table 1 was editorially corrected and Section 16 was added in December 2000.
1. Scope one uses any means available to attempt to separate the coating
from the substrate. This may be prying, hammering, bending,
1.1 This practice describes simple, qualitative tests for
beating, heating, sawing, grinding, pulling, scribing, chiseling,
evaluating the adhesion of metallic coatings on various sub-
or a combination of such treatments. If the coating peels,
stances.
flakes, or lifts from the substrate, the adhesion is less than
1.2 This standard does not purport to address all of the
perfect.
safety concerns, if any, associated with its use. It is the
2.6 If evaluation of adhesion is required, it may be desirable
responsibility of the user of this standard to establish appro-
to use one or more of the following tests. These tests have
priate safety and health practices and determine the applica-
varying degrees of severity; and one might serve to distinguish
bility of regulatory limitations prior to use.
between satisfactory and unsatisfactory adhesion in a specific
2. Significance and Use application. The choice for each situation must be determined.
2.7 When this guideline is used for acceptance inspection,
2.1 These tests are useful for production control and for
the method or methods to be used must be specified. Because
acceptance testing of products.
the results of tests in cases of marginal adhesion are subject to
2.2 Interpreting the results of qualitative methods for deter-
interpretation, agreement shall be reached on what is accept-
mining the adhesion of metallic coatings is often a controver-
able.
sial subject. If more than one test is used, failure to pass any
2.8 If the size and shape of the item to be tested precludes
one test is considered unsatisfactory. In many instances, the
use of the designated test, equivalent test panels may be
end use of the coated article or its method of fabrication will
appropriate. If permitted, test panels shall be of the same
suggest the technique that best represents functional require-
material and have the same surface finish as the item to be
ments. For example, an article that is to be subsequently
tested and shall be processed through the same preplating,
formed would suggest a draw or a bend test; an article that is
electroplating, and postplating cycle with the parts they repre-
to be soldered or otherwise exposed to heat would suggest a
sent.
heat-quench test. If a part requires baking or heat treating after
plating, adhesion tests should be carried out after such post-
3. Bend Tests
treatment as well.
3.1 Bend the part with the coated surface away over a
2.3 Several of the tests are limited to specific types of
mandrel until its two legs are parallel. The mandrel diameter
coatings, thickness ranges, ductilities, or compositions of the
should be four times the thickness of the sample. Examine the
substrate. These limitations are noted generally in the test
deformed area visually under low magnification, for example,
descriptions and are summarized in Table 1 for certain metallic
43, for peeling or flaking of the coating from the substrate,
coatings.
which is evidence of poor adhesion. If the coating fractures or
2.4 “Perfect” adhesion exists if the bonding between the
blisters, a sharp blade may be used to attempt to lift off the
coating and the substrate is greater than the cohesive strength
coating. With hard or brittle coatings, cracking usually occurs
of either. Such adhesion is usually obtained if good electro-
in the bend area. Such cracks may or may not propagate into
plating practices are followed.
the substrate. In either case, cracks are not indicative of poor
2.5 For many purposes, the adhesion test has the objective
adhesion unless the coating can be peeled back with a sharp
of detecting any adhesion less than “perfect.” For such a test,
instrument.
3.2 Bend the part repeatedly, back and forth, through an
These test methods are under the jurisdiction of ASTM Committee B-8 on
angle of 180° until failure of the basis metal occurs. Examine
Metallic and Inorganic Coatingsand are the direct responsibility of Subcommittee
the region at low magnification, for example, 103, for sepa-
B08.10on General Test Methods.
Current edition approved Oct. 10, 1997. Published March 1998. Originally
ration or peeling of the coating. Prying with a sharp blade will
published as B 571 – 79. Last previous edition B 571 – 91 (1997).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 571
TABLE 1 Adhesion Tests Appropriate for Various Coatings
A
Coating Material
Lead and Tin and
Adhesion Test
Nickel and
Cadmium Chromium Copper Lead/Tin Nickel Palladium Rhodium Silver Tin/Lead Zinc Gold
Chromium
Alloy Alloy
Bend +−+++ + + + + + + +
Burnish −++−+ + − − + − + −
Chisel/knife +++++ − + − + + − +
Draw −−+−+ + − − − − + −
File −++++ + − + + + − +
Grind and ++−−+ + + − − + + −
saw
Heat/quench −++++ + − − + + − +
Impact +−+−+ + − − − − + −
Peel −++−+ − − − + + − +
Push −−−−+ + − − − − + −
Scribe −−+−+ − − − − − − −
A
+ Appropriate; − not appropriate.
indicate unsatisfactory adhesion by lift off of the coating. file across the sawed edge from the substrate toward the
coating so as to raise it, using an approach angle of approxi-
4. Burnishing Test
mately 45° to the coating surface. Lifting or peeling is evidence
4.1 Rub a coated area of about 5 cm with a smooth-ended of unsatisfactory adhesion.
tool for approximately 15 s. A suitable tool is a steel rod 6 mm 7.2 This technique is not suitable for thin or soft coatings.
in diameter with a smooth hemispherical end. The pressure
8. Grind-Saw Test
shall be sufficient to burnish the coating at each stroke but not
8.1 Hold the coated article against a rough emery wheel so
so great as to dig into it. Blisters, lifting, or peeling should not
that the wheel cuts from substrate toward the deposit in a jerky
develop. Generally, thick deposits cannot be evaluated satis-
or bumpy fashion. A hack saw may be substituted for the
factorily.
wheel, making sure to saw in the direction that tends to
5. Chisel-Knife Test
separate the coating from the substrate. Lifting or peeling is
evidence of unsatisfactory adhesion.
5.1 Use a sharp cold chisel to penetrate the coating on the
8.2 This technique is especially effective on hard or brittle
article being evaluated. Alternatively the chisel may be placed
coatings but is not suitable for thin or soft coatings.
in back of an overhang area of the coating or at a coating-
substrate interface exposed by sectioning the article with a saw.
9. Heat-Quench Test
A knife may be substituted for the chisel with or without
9.1 Heat the coated article in an oven for a sufficient time
hammering or light tapping. If it is possible to remove the
for it to reach the temperature shown in Table 2. Maintain the
deposit, the adhesion is not satisfactory. Soft or thin coatings
temperature of the oven within 10°C of the nominal. Coatings
cannot be evaluated for adhesion by this method.
and substrates that are sensitive to oxidation should be heated
in an inert or reducing atmosphere or a suitable liquid. Then
6. Draw Test
quench the part in water or other suitable liquid at room
6.1 Form a suitable sample about 60 mm in diame
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