Improvement of corrosion resistance of friction stir welded joint of 7N01-T5 aluminum alloy by micro-arc oxidation

The ceramic coatings were prepared on surface of friction stir welded joint of 7N01-T5 aluminum alloy by micro arc oxidation technology. The morphology and phase constituent of the micro arc oxidation coatings were studied by SEM,XRD. The corrosion resistance of the friction stir welded joint oxidized and sealed was tested through the neutral salt spray (NSS) test. The results show that micro arc oxidation coating formed on the FSW joint is uniform,and there are many discharge micro-porous like crater and melting,sintering traces on the surface,and which are mainly composed of α-Al₂O₃ and γ-Al₂O₃ phase. Micro arc oxidation ceramic coating has excellent corrosion resistance. Boiling water seal treatment can generate a hydrated alumina, which makes the hole wall inflated and the pore size decreaed, the corrosion resistance of the coatings can be greatly enhanced, and the weight loss is only 2.6 mg after enduring 96 h in NSS test.