Research On Scanning Micro-arc Oxidation Process And Ceramic Layer Characteristics Of Aluminum Alloy Friction Stir Welding Joints

The high-speed train uses an aluminum alloy car body to achieve its lightweight,and the car body material uses A7N01 aluminum alloy.Friction stir welding is an effective method for welding straight and long welds on car bodies.Corrosion of friction stir welding joints is a problem that needs to be solved in the application.This paper takes A7N01 friction stir welding joint as the research object,and proposes the technical means of using scanning micro-arc oxidation technology to modify the joint surface to improve the corrosion resistance of the joint.Through the method of combining experiment and simulation technology,from scanning micro-arc oxidation spraying Research has been carried out in three aspects:system design,micro-arc oxidation treatment process and ceramic layer performance test.The main research contents and results of this paper are as follows:(1)Based on the existing scanning micro-arc oxidation platform,with the goal of improving processing efficiency,the scanning micro-arc oxidation spray system is designed by combining electric field simulation,flow field simulation and experimentation,especially for the new flexible and flexible control multiple outlet nozzles.(2)For the A7N01 FSW connector,the electrolyte system and process parameters of the scanning micro-arc oxidation treatment process are studied,and the programming module of the manipulator teaching system is used to achieve the precise control of the nozzle movement trajectory of the spray system and realize the ceramic layer Efficient and high-quality preparation.(3)Analyze the micro morphology and phase composition of the ceramic layer in different areas of the FSW joint(weld seam area,heat affected area,base material area)using scanning electron microscopy and other analytical methods.The micro morphology of the ceramic layer in different areas does not exist.The obvious difference is that the composition phase is basically the same,mainly composed of?-Al₂O₃ and?-Al₂O₃.The bonding strength between the ceramic layer and the substrate was characterized by tensile tests.The corrosion resistance of the ceramic layer of FSW joints was studied by electrochemical tests,immersion experiments and salt spray corrosion experiments.The results showed that the ceramic layer significantly improved the corrosion resistance of FSW joints.