Fabrication and performance of black MAO coatings on zinc alloys

Black functional coatings were fabricated on the surfaces of three types of zinc alloys with varying aluminum content via micro-arc oxidation (MAO) technology. The coatings were characterized in terms of their macroscopic and microscopic morphologies, elemental composition, abrasion-corrosion, as well as the absorptivity and emissivity profiles. The results showed that the coatings have a high absorptivity (>83%) and emissivity (>92%), indicating strong thermal control properties. The coating thickness reached 22 μm, achieving a blackness value of approximately 36 and hardness exceeding 217 HV 0.5 . The MAO coating formed on zinc alloys with medium Al content exhibited the highest bonding strength, optimal blackness, and enhanced corrosion and wear resistance. It can be concluded that the Al content plays a significantly role in the structure and performance of black MAO coatings on zinc alloys. The structure and functionality of black MAO coatings on zinc alloys are significantly influenced by the Al concentration.