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Adhesion of organic coatings III

Adhesion of organic coatings III

If indeed the number of available OH groups at the surface of the substrate determines the overall adhesion force, as we already did see in II, it must be useful to optimise this number of OH groups. Different chemical treatments like exposure to acid or caustic solution, or heating the sample do indeed result in a different OH density at the surface of aluminium oxide. In the figure we can see on the x-axis that the fraction OH groups as determined with XPS as expected obtains its highest value for the caustic treatment. Along the y-axis we observe a measure for the adhesion force for ester model molecules as determined by Infrared analysis. A clear relation exists between the number of OH groups and the bonding strength of these molecules. Mechanical test did confirm this for real coating systems.

From: J.H.W. de Wit, J. van den Brand, F.M. de Wit, and J.M.C. Mol, CORROSION SCIENCE AND TECHNOLOGY, Vol.7, No.1(2008), pp.50~60

Adhesion of Model Molecules to Metallic Surfaces, the Implications for Corrosion Protection