What Is Adhesion Tester
Adhesion Tester is the tendency of dissimilar particles and surfaces to cling to one another. That why Adhesive strength of coatings are crucial importance to enable the material meet the basic functions of protection and decoration. Adhesion test in the coating industries is necessary to ensure the coating will adhere properly to the application substrates.
Mainly the adhesion testing after the coating process will quantify the strength of the bond between substrate and coating. And also between different coating layers, we call the cohesive strength of materials.
The adhesive strength of application coatings depends heavily on the quality of the pre-treatment process prior to the coating application. And also compatibility between coatings or coating and substrate is a key factor.
What The adhesion test use for ?
Adhesion test is use as part of inspection and maintenance procedures, to help detecting potential coating failures. Also control the quality of a coating job or to define if an existing coating system has to be remove before applying new paint. There are three different tests to measure the resistance of paints and coatings from substrates: cross-cut test, scrape adhesion, and pull-off test.
Is a right angle lattice pattern is use to measure the resistance of paints and coatings to separation from substrates. The pattern is cut into the coating and penetrates through the substrate. A specify pressure sensitive tape is applying to the sample and pull off. This testing method is often use as a fast pass or fail test. If this test is use on a multi-coat sample, assessment of the resistance to separation of individual layers of the coating from each other can be made.
The scrape adhesion test measures the determination of the adhesion of organic coatings applying to smooth and flat panel surfaces. It is helpful in giving relative ratings for a number of coat panels showing significant differences in adhesion. The materials being test are applies at uniform thickness to flat panels, mainly some sort of sheet metal. When the materials have dry the adhesion is determine by pressing panels under a round stylus. That is load with increasing amounts of weight until the coating is remove from the substrate surface.
Unlike the other methods, this method maximizes the tensile stress, therefore results may not be comparable to the others. The test is done by adhering a dolly perpendicular to the surface of a coating with an adhesive.
Then the testing apparatus is attach to the loading fixture. And is aligned to apply tension perpendicular to the test surface. The force that is applied gradually increases and is monitored until a plug of coating is detached, or a previously specify value is reach.
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