铝合金搅拌摩擦焊表面冷喷涂层的结构与耐蚀性

采用冷喷涂技术在2219铝合金搅拌摩擦焊接头上制备Al涂层,以提高搅拌摩擦焊接头耐蚀性。通过数字显微镜、扫描电镜、电化学工作站对Al涂层的结构及耐蚀性进行表征。结果表明:冷喷Al涂层质量良好,孔隙率仅为0.77%,涂层内部存在等轴晶、细化晶粒以及拉长晶粒,涂层界面以机械咬合为主,涂层/接头区界面质量明显优于涂层/母材区界面;电化学数据显示,涂层腐蚀敏感性较低,自腐蚀电位和腐蚀电流密度均低于热影响区,冷喷涂层降低了搅拌摩擦焊接头的腐蚀敏感性;晶间腐蚀实验表明,腐蚀6 h后,涂层最大腐蚀深度仅为热影响区最大腐蚀深度的50%,证明冷喷涂技术显著改善了搅拌摩擦焊接头的耐腐蚀性。

Structure and corrosion resistance of cold spray coating prepared on friction stir welded high strength aluminum alloys

In order to improve the corrosion resistance of the friction stir welding(FSW), the Al coating was prepared on the 2219 aluminum alloy friction stir welding joint via cold spraying technology. The structure and corrosion resistance of the Al coating were characterized by digital microscope, scanning electron microscope and electrochemical workstation. The results indicate that Al coating deposited by cold spraying technology on the FSW joint is a compact structure, and the porosity is 0.77%. There are equiaxed crystals, refined grains and elongated grains in the coating. The interface of the coating is mainly mechanical occlusion.The interface quality of the coating/joint area is obviously better than that of the coating/BM. Coating corrosion sensitivity is lower than that of FSW joints, and the corrosion potential and corrosion current density of the coating are far below the heat affected zone.Cold spray coating reduces the corrosion sensitivity of FSW joints. The intergranular corrosion test shows that the corrosion resistance of the coating is better than that of the FSW joint. In terms of corrosion depth, the coating is only 50% of HAZ after 6 h’s corrosion. The cold spray technology prominently improves the corrosion resistance of the FSW joint.