Color coated steel coil coating adhesion is an important technical indicator to evaluate the quality. At present, T-bend test is used to characterize the adhesion of color coated steel coil coating in domestic and overseas.
However, the part of color coated board will appear rapid deterioration of coating adhesion when the storage time is lengthened. Affecting the normal use of color coated steel sheet.
It was found in the experiment that even the coating with the worst aging performance was used, if the substrate is galvalume substrate, the aging performance of coating adhesion in color coated steel coil is also better. The main reason for this situation is the special surface structure of the galvalume substrate.
When the coating impermeability of colored steel coil is poor, water, oxygen and corrosive ions will penetrate into the surface of the galvalume substrate, then the zinc-rich zone in the interdendritic network is first corroded, and the oxidation product fills the interdendritic interstice, thereby reducing the corrosion rate.
So the aging performance of coating adhesion in color coated steel coil performance best with this kind of substrate.