DIN SPEC 91063
Adhesion of coatings
Haftfestigkeit von Beschichtungen
Procedure
Technical Report
Overview
The determination of adhesion of coatings is one of the important prerequisites for the assessment of the protective function of coatings. This DIN SPEC (Technical Specification) is a compilation of the methods used for assessment of the adhesion of coatings on an undercoat, whereby this may be an underlying layer or the substrate. The test and evaluation methods are described in clauses 4, 5 and 6. In the case of standardized test methods, reference is made to the corresponding standards with regard to procedure and interpretation of results. The methods are depicted in the overview tables A.1, A.2 and A.3 of Annex A for comparison. In many cases, adhesion cannot be sufficiently assessed by application of one method only. The purely physical methods for measuring the adhesion are those where mechanical quantities (for example, force and torque) are directly measured. All other methods are based on the assessment of the behaviour under mechanical stress following practical conditions. Regarding these methods, viscoelastic properties have a major influence on the assessment of the adhesion, so that comparative tests can only be made within one method. Every method has its specific application. An unsuitable method may lead to a false statement. All test methods for assessment of adhesion require certain examiner experience, especially for recognition of the parting plane. For most test methods, test results are dependent on the film thickness of the coating under test, amongst others. Furthermore, some methods might exhibit differences between tests on a sample sheet of metal and in practice due to differing roughness. Delamination effects caused by weathering and corrosion effects are not covered by this DIN SPEC (Technical Specification). It is no measure for adhesion if mainly cohesion failures occur during adhesion testing; statements can be made on the protective effect of the coating against corrosion, however. The Committee responsible for this standard is NA 002-00-07-14 AK "Haftfestigkeit und Härte" ("Adhesive strength and hardness") at DIN.
