In my experience, to coat a metallic substrate with a polymeric paint is a matter of trial and error. Such strategy is time consuming and sometimes frustrating. To have a model to evaluate beforehand if certain type of polymeric resins may have a suitable adhesion on a certain metal would be very helpful. Does anyone know an empirical or analytical model?
Dear Dr. Jerson Peralta ,
the Cross Hatch Test is definitely the simplest test to define the degree of adhesion of a coating (generally paint) on a metallic or non-metallic substrate. As we said earlier. The reference standard is ISO2409 where the method and the operand mode are illustrated through reference tables and images.
What are the key steps:
■ Grasp the cutting tool and make a cross incision by dragging the tool with force and correct pressure, taking care not to create interruptions during dragging, in which case repeat the test at another point. It is important that the lines of the lattice are homogeneous without tearing and that the cut has come up to touch the substrate.
■ The next step is to brush the crosshair surface diagonally. Alternatively, it is more effective to apply an adhesive tape for tear-off cross-cut tests, such as Permacel or 3M, directly over the metric grating with a firm tear.
■ The final phase consists in carefully observing (better with the use of a lens) the area of the reticle to check the level of integrity of the lines and squares created by comparing the result with the reference tables contained in the ISO2409 standard with the aim to precisely define the degree of adhesion obtained from the test.
For more details, I suggest you to have a look at the source:
-How to check the adhesion degree of a coating? Discover the "Squaring" test by ARW MISURE
Available at: https://arwmisure.com/uno-dei-test-piu-utilizzati-per-verificare-il-grado-di-adesione-di-un-rivestimento-la-prova-di-quadrettatura/
My best regards, Pierluigi Traverso.
If you just want to make your polymer adhere, it often helps to modify the metal surface.
on silicon wafers, we used to silanize the surface with hexamethyldisilazane vapor in a special oven, but there are other techniques that may work for the metals you use.
most metals have a thin layer of oxide on the surface - more nonpolar polymers often don’t adhere well. So making the surface more
nonpolar (with trimethylsilyl groups) improves adhesion.
Hi Dr. Jerson Peralta,
Modification of metallic-surface as suggested by James E.H. is usually one of an important engrg processing step.
Especially, when adhesion of coating is subjected for a thermal-cycle-test, the failure rate could be higher due to miss-match of thermal-expansion factor.
Therefore, introduce an interface-molecular layer to act as 'bridging' bwt polymeric-paints against metallic surfaces is necessary.
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