EN 13144-2017 pdf download.Metallic and other inorganic coatings – Method for quantitative measurement of adhesion by tensile test.
4.2.2.2 Test stamps
For use with the centrifuge, monolytic or modular test stamps made of machined stainless steel or other metals such as copper or tungsten.copper (monolytic test stamps, i.e. mass body and adherend are of the same material) or with additional insertable one-sided adherends made of stainless steel or any other material (modular test stamps, i.e. mass body and adherend are of different materials), having adherend diameters of 20 mm, 10 mm or 7 mm in accordance with EN 15870 and EN ISO 4624 (unless otherwise agreed upon).
Prior to use, the face acting as adherend shall be machined perpendicular to the major axis of the test stamp.
4.2.2.3 Planar samples
For use with the centrifuge made of the coating/substrate system as processed, having an area sufficiently larger than the support by the guiding sleeve.
Depending on the thickness of the planar sample, i.e. the coating/substrate system to be tested, in particular for thin metallic or any polymeric substrates, a reinforced backside support shall be applied as otherwise unwanted deformations may affect the testing result.
At bonding, the faces of the substrate and the test stamp shall be aligned perpendicular by using the guiding sleeve.
4.3 Adherend preparation
The preparation of the adherend of planar samples can be realized either by cutting or etching after deposition or by masking prior to deposition resulting in adherends with diameters of 20 mm, 10 mm or 7 mm. Cutting can be recommended only for metallic substrates, whereas chemical or electrochemical etching and masking can be applied for all substrate materials. In general, any substrate damage has to be avoided.
Cutting can be done for example with a carbide tool or a scribing iron, capable of cutting the coating through to the substrate, along the circumference of the adherend of the test block or the test stamp. Cutting is in particular used for thicker (more than 10 im) metallic coatings on metallic substrates, prior to the application of the adhesive.
Especially in the case of thin coatings (in the range of 10 tm or below), glass or polymeric substrates there is a high risk of damaging the coating and influencing the results unfavourably. Thus such samples are tested as they are without cutting through the coating. In this case the rupture force of the coating adds to the pull-off forces, but for thin coatings this influence is tolerated in order to avoid larger influences from substrate damage.
The adhesion of the adhesive to the coating can be improved by slightly abrading the surface of the coating prior to attaching the adhesive coated test block or test stamp; however, this is only applicable when slight abrasion or roughening does not reduce the coating thickness significantly and does not influence the coating’s adhesion to the substrate or an underlayer.
4.4 Adhesives and their application
Special attention shall be given to the selection and application of adhesives for use in the test.
The selection of an adhesive class (e.g. cyanoacrylates, epoxides, polyurethanes and others) and a specific adhesive type have to consider the materials of both the coating to adhesive and the test block or test stamp to adhesive interface.
Deformable substrates shall be coated on both faces and subjected to the sandwich method when using a tensile testing machine (see 4.5.1) or be reinforced by an additional backside support when using the centrifuge (see 4.5.4).
All surfaces shall be clean and dry before applying the adhesive.
The adhesives shall be prepared and applied in accordance with the manufacturer’s instructions and in a way that no shear forces are introduced in the assembly. The minimum quantity of adhesive necessary to obtain a uniform adhesive film thickness between the constituents of the test assembly shall be used; any excess adhesive shall be removed. Pot life, setting and curing conditions shall be in agreement with the specification of the adhesive and provided in the test report
The adhesion of the adhesive to the test block or test stamp should be improved by slightly abrading the adherend of the test block or the test stamp prior to applying the adhesive onto it.EN 13144-2017 pdf download.