Abstract
Laser surface melting of aluminum 7075-T6 alloy was combined with the adsorption of aminopropylphosphonic acid as a molecular adhesion for the improvement of the corrosion resistance and wet-adhesion strength of epoxy adhesive film coated substrates. A clear correlation between the morphological and chemical surface states with the electrochemical and adhesive properties could be established. A continuous laser with a wavelength of 1064 nm was applied and the resulting changes in the microstructure were determined by means of scanning electron microscopy (SEM) and focused ion beam (FIB). The chemical structure of the laser-modified alloy surface was investigated using XPS and diffuse reflectance FTIR spectroscopy. Electrochemical measurements such as linear sweep voltammetry and impedance spectroscopy were performed to investigate the corrosion properties of the bare and adhesive coated alloy. It could be shown that surface laser melting under ambient conditions in combination with the molecular adhesion promoter leads to interfaces that are both highly delamination-resistant and show excellent wet-adhesion. The results could be explained by the combination of mechanical interlocking, chemical bond formation at the interface and the inhibition of corrosion reactions at the adhesive/alloy interface.
Published Version
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