Abstract
The adhesion between coating and a flat metal surface hasbeen investigated by measurements. The setup is based on theformation of a blister by injecting nitrogen gas under pressurebetween the coating and the substrate. The adhesion energy isdetermined by recording the pressure as a function of therecorded blister radius development. A laser is moved over theblister in 2D with two programmable step engines to measurethe blister profile and thereby the radius of the blister betweensuccessive pressure increases. The design and operation of theinstrument are described and an evaluation of its performanceand limitations is given. The method could be useful for accuratemeasurement of adhesion of many types of surface coatings tometal and, possibly, to other substrates, as well as for studies ofthe various factors that influence adhesion. A better accuracy ofthe laser for measuring the blister profile would improve thesetup.We treated aluminium surfaces in different manners (sandpaper, polishing and blowing using glass particles) but found nosignificant impact on the adhesion energy between the x-linkedcoating layer and the metal. The adhesion energy measurementshowever have a large scatter. The coating layer that was not xlinkedhad a much lower adhesion energy.
Highlights
Most of the work on constrained blisters has examined the de-bonding of the blister from the surface underneath as the pressure is applied from below (Figure 1)
The coating layer is lifted by the applied pressure and form a blister [8]
D is a material constant [7] for the polymer coating or layer
Summary
Most of the work on constrained blisters has examined the de-bonding of the blister from the surface underneath as the pressure is applied from below (Figure 1). The coating layer is lifted by the applied pressure and form a blister [8]. The mode where the applied pressure affects the edge of the debonding the most and not the compression and stretching of the substrate material is preferable. For the last expression (in 3) we observe that the critical pressure (Pcr) for debonding is less dependent of the tensile modulus (E) and the thickness of the layer (h) and more strongly dependent of the adhesion energy than the other expressions for the other experimental situations (in 1 and 2). With an elastic behaviour of the coating layer in response to an internal pressure a pressurised blister test could be a good method for measuring interfacial adhesion [10, 11]. When the thickness h of the coating is thin it is simpler to estimate the debonding diameter
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