ASTM D4541 Test Fixture
ASTM D4541 -This test method covers a procedure for evaluating the pull-off strength (commonly referred to as adhesion) of a coating system from metal
substrates.
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ASTM D4541 – Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers
ASTM D4541 – Tensile adhesion strength of thermal spray coatings
ASTM D4541 -This test method covers a procedure for evaluating the pull-off strength (commonly referred to as adhesion) of a coating system from metal
substrates.
Pull-off strength of coatings from concrete is described in Test Method D7234.
This test offers two test protocols. Protocol 1 (test to fracture) determines the greatest perpendicular force (in tension) that a surface area can bear before a plug of
material is detached.
Protocol 2 (pass/fail) determines if the coated surface remains intact at a defined load criteria.
Fracture will occur along the weakest plane within the system comprised of the test fixture, glue, coating system, and substrate, and will be exposed by the fracture surface.
This test method maximizes tensile stress as compared to the shear stress applied by other methods, such as scratch or knife adhesion, and results may not be comparable.
NOTE 1: The procedure in this standard was developed for metal substrates, but may be appropriate for other rigid substrates such as plastic and wood.
Factors such as loading rate and flexibility of the substrate must be addressed by the user/specifier.
NOTE 2: The procedure in this standard was developed for use on flat surfaces.
Depending on the radius of the surface, the results could have greater variability with lower values and averages.
Pull-off strength measurements depend upon material, instrumentation and test parameters.
Results obtained by each test method may give different results.
Results should only be assessed for each test method and not be compared with other instruments.
There are five instrument types, identified as Test Methods B-F. It is imperative to identify the test method used when reporting results.
NOTE 3: Method A, which appeared in previous versions of this standard, has been eliminated as its main use is for testing on concrete substrates
(see Test Method D7234).
This test method describes a class of apparatus known as portable pull-off adhesion testers.2
They are capable of applying a concentric load and counter load to a single surface so that coatings can be tested even though only one side is accessible.
Measurements are limited by the strength of adhesive bonds between the loading fixture and the specimen surface or the cohesive strengths of the glue,
coating layers, and substrate.
This test can be destructive and spot repairs may be necessary.
*** Before conducting ASTM D4541 , it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.
