Mg-1Zn-1Mn合金微弧氧化膜在SBF模拟体液中的腐蚀行为

Corrosion behavior of micro-arc oxidation film of Mg-1Zn-1Mn alloy in SBF simulated body fluid

采用微弧氧化工艺在Mg-1Zn-1Mn合金表面制备微弧氧化陶瓷膜。借助扫描电镜、激光扫描共聚焦显微镜、能谱分析仪和X射线衍射分析仪对氧化膜的微观结构和相组成进行表征,通过电化学方法和浸泡实验研究陶瓷膜在模拟体液中的耐腐蚀性。结果表明：微弧氧化5 min可在Mg-1Zn-1Mn合金表面形成光滑平整、厚度为10μm并与基体结合良好的陶瓷膜,其主要由Mg O和Mg2Si O4组成,为典型的多孔结构;微弧氧化陶瓷膜可使Mg-1Zn-1Mn合金产生钝化,显著提高合金在SBF溶液中的耐腐蚀性,腐蚀速率降低至0.026 mm/a,耐腐蚀性提高近10倍。陶瓷膜裂纹和腐蚀介质与陶瓷膜反应造成的破损使得腐蚀液渗入到合金与陶瓷膜界面,导致SBF溶液与合金接触发生反应,造成点蚀和丝状腐蚀。

Ceramic film was prepared on the surface of Mg-1Zn-1 Mn alloy（mass fraction,%） by micro-arc oxidation（MAO） process,microstructure and phase composition of the film were characterized by means of scanning electron microscopy,laser scanning confocal microscope,energy disperse spectroscopy analysis and X-ray diffractometer,and the corrosion resistance of the film was measured by electrochemical method and immersion test. The results show that the ceramic film with smooth thickness of 10 μ m and good binding to the substrate can be formed on the surface of the Mg-1Zn-1 Mn alloy by micro-arc oxidation for 5 min,and the film is mainly composed of MgO and Mg2 SiO4 phases,and are typical porous structure. The micro-arc oxidation ceramic film can passivate Mg-1Zn-1 Mn alloy,and improve the corrosion resistance of the alloy in SBF solution,and the corrosion rate is reduced to 0. 026 mm/a,and the corrosion resistance is increased by nearly 10 times compared with the alloy matrix. The cracks of the ceramic film and the damage caused by the reaction of corrosion medium with ceramic film make the corrosion liquid infiltrate into the interface of the alloy and ceramic film,and lead to the contact reaction between SBF solution and alloy,resulting in pitting corrosion and filamentous corrosion.