微弧氧化膜层的组分质量比率、结构与性能

Component Mass Ratio, Microstructure and Performance of Micro-arc Oxidation coating

摘要:

为了同时提高AZ61的MgF₂+MgO微弧氧化膜层的电化学腐蚀与磨损性能,本文运用复合电介质顺序放电学术思想,通过减弱击穿熔体的喷发,使膜层进一步致密,进而使其性能得到提高。膜层的MgF₂-MgO质量比率α、微观组织、电化学腐蚀与磨损性能的研究结果表明：α=1.2时,减弱击穿熔体喷发的效果显著好于α=0.1和11.8,膜层的内部致密层厚度可提高到3.6 μm,是现有微弧氧化膜层的3倍,外部疏松层的阻抗可提高到13555 Ω cm^₂,比α=0.1和11.8的大30%。该膜层可将AZ61的自腐蚀电压Ecorr由-1.912提高到-0.455 V_SCE、自腐蚀电流Icorr由378.6减小到0.453(10^_-6 A/cm^₂)、磨损率由921降低到0.5(10^_-5 mm^₃/N.m)。本研究为制备高性能微弧氧化膜层提供了一种新模式。

Abstract:

In order to improve the electrochemical corrosion and wear performance of MgF₂+MgO MAO (micro-arc oxidation) coating on AZ61 simultaneously, composite dielectric ordinal discharge thought was used to weaken the eruption of breakdown melt and hence densify the coating and enhance its performance. α (MgF₂-MgO mass ratio), microstructure, electrochemical corrosion and wear performance of coatings were investigated. The results show that the weakening effect on eruption of breakdown melt for coating with α=1.2 is obviously better than that with α=0.1 and 11.8. The thickness of inner dense layer is thickened to 3.6 μm, which is about three times as thick as that of the existing MAO coating. The impedance of outer loose layer is enhanced to 13555 Ω cm^₂, which is about 30% larger than that of α=0.1 and 11.8. Ecorr (corrosion potential) of AZ61 is increased from -1.912 to -0.455 V_SCE, Icorr (corrosion current density) is decreased from 378.6 to 0.453 (10^_-6 A/cm^₂) and the wear rate is reduced from 921 to 0.5 (10^_-5 mm^₃/N.m) by this densified micro-arc oxidation coating. This investigation provides a novel processing mode for outstanding MAO coating.