Investigating how Cu content and oxidation time affect the hardness and corrosion resistance of MAO coatings on Al alloy

This study investigated the effect of copper (Cu) content on the thickness, morphology, and phase composition of micro-arc oxidation (MAO) coatings on Al–Cu alloys, with 0.1% of titanium (Ti) with oxidation periods of 60 and 120 minutes. The research assessed how Cu concentration influences the microhardness, porosity, and corrosion resistance of the coatings. Using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), the coatings were characterized to understand their structural and compositional properties. After 60 minutes of oxidation, the MAO coating on the Al–3Cu alloy exhibited the lowest porosity (2.9%) and the highest hardness (2.479 HV), making it the most robust among the coatings. Whereas, the MAO coating on the Al–9Cu alloy demonstrated the lowest corrosion resistance due to its higher porosity, which allowed corrosive agents to penetrate more easily. The study revealed that Cu content significantly affected the phase composition and porosity, influencing the overall corrosion resistance of the MAO coatings. Additionally, both Cu content and oxidation duration contributed to the increased thickness of the coatings, with longer oxidation times resulting in thicker and more protective films. These findings provide valuable insights into optimizing MAO coatings for Al–Cu alloys, highlighting the importance of controlling Cu content and oxidation parameters to enhance hardness, and corrosion resistance.