Studies of the mechanism of adhesion of polymer coatings on the oxidized surface of aluminum and magnesium alloys

The mechanism of adhesion of styrene-acrylic polymer on the oxidized surface of aluminum alloy AMg3 and magnesium alloy MA20 is investigated. It is shown that the adhesion of the polymer coating to the chemically oxidized surface of the aluminum alloy is much higher than to the anodic film on the magnesium alloy. The relationship between the adhesive strength of the substrate and the concentration of hydroxyl ions capable of participating in condensation reactions in it has been established. To explain the observed patterns, the chemical composition and morphology of the alloys were studied using photoelectron XPS spectroscopy and EMS analysis. Methods of modification of conversion coatings on magnesium and aluminum alloys with ethylene glycol, which significantly improve the adhesion of polymer layers to them, are proposed. It has been established that ethylene glycol actively interacts with ions of these alloys to form macromolecules of magnesium and aluminum ethylene glycolate embedded in the hydroxide lattice of the conversion coating. These coatings contain a significant amount of hydroxyl ions involved in the formation of chemical bonds. Mechanical and electrochemical tests of the modified coatings were carried out in order to optimize the compositions and modes of their formation.