Preparation of Overall Ceramic Coating on 6061-7075 Dissimilar Aluminum Alloy Friction Stir Welded Parts

Through micro-arc oxidation treatment, the friction stir welded parts (connectors) of 6061 and 7075 aluminum alloys were integrally wrapped by a layer of ceramic film. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical workstation were used to analyze the morphology and composition of the surface film on the base metal and weld zone, and based on the detection results, the growth mechanism of the monolithic ceramic film was deduced. The results showed that the film layer on the surface of the connector was dense after the overall micro-arc oxidation. The main components of the film on the surface 6061 and 7075 were α-Al₂O₃, γ-Al₂O₃ and a small amount of Al₂SiO₅, while the weld zone was mainly composed of α-Al₂O₃ and γ-Al₂O₃. Micro-arc oxidation reduced the corrosion potential difference between different regions of the connector and significantly improved the overall corrosion resistance of the connector.