Preparation of multi-colored coatings on magnesium alloy surfaces using hydrothermal methods

Abstract

With advances in technology, the importance of magnesium alloy is becoming increasingly significant, and thus its poor corrosion resistance and single color defects are becoming more and more prominent. At present, the preparation of coatings with adjustable colors on the surface of magnesium alloy has been less studied. To address this problem, a corrosion-resistant coating with a variety of distinctive colors was successfully prepared on the surface of magnesium alloy via hydrothermal method. In this paper, by varying the concentration of reagents, the regulation mechanism of the coating color was investigated, and it was found that with the increase of the concentration of hydroxide ions, the color gradually became darker, and the wavelength of the reflected light became shorter accordingly. These findings indicate a key role for hydroxide ions in the coating color transformation process. In addition, the prepared coatings were tested for adhesion and corrosion resistance. The adhesion test grade was 5B, which indicates that the prepared coating shows good adhesion and uniform color. Electrochemical and immersion experiments proved that the coating has strong corrosion resistance, the coating not only provides the magnesium substrate with bright colors but also offers stronger protection to the substrate. This enhancement significantly improves the appearance and service life of magnesium alloys, making them well-suited for large-scale applications and providing robust support for their broader utilization.