脉冲频率对镁合金微弧氧化膜层在仿生液中耐蚀性的影响

Effect of Pulse Frequency on the Corrosion Behavior of Microarc Oxidation Coating on Mg Alloys in SBF

摘要:

研究了微弧氧化过程中不同电源脉冲频率下制备的膜层在仿生液中的电化学腐蚀行为。对膜层及腐蚀产物的微观组织，孔隙率，腐蚀形貌及相组成进行了分析。采用动电位极化曲线(Tafel)和电化学阻抗谱（EIS）法对膜层的耐腐蚀性能进行评价。结果表明，脉冲频率对AZ31镁合金微弧氧化膜层的耐蚀性有重要影响，随着频率的增加，腐蚀电流密度减小，而电化学阻抗增大。因此在本研究范围内，频率3000 Hz下制备的微弧氧化膜层具有最强的耐腐蚀性能。

Abstract:

The corrosion behavior of microarc oxidation (MAO) coatings prepared on AZ31 Mg alloys at 50, 100, 300, 500, 1000 and 3000 Hz was studied in simulated body fluid (SBF). The microstructure, porosity, and chemical phase composition of the samples before and after corrosion were analyzed. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to characterize the corrosion performance. The results show that pulse frequency plays an important role on the corrosion resistance of the MAO coating. The corrosion current density decreases and electrochemical impedance increases with the increase of the pulse frequencies, which result from the dense microstructure at high frequency. The coating produced at 3000 Hz exhibits the largest corrosion resistance with the densest morphology in the present study.