ZM6铸造镁合金微弧氧化膜层性能研究

Performance of Micro Arc Oxidation Coating of ZM6 Cast Magnesium Alloy

针对ZM6铸造镁合金,为获得综合性能优异的陶瓷膜层,在硅酸钠和氢氧化钠的碱性溶液中,用双向脉冲电源进行微弧氧化处理。采用环境扫描电镜(SEM)、X射线衍射(XRD)研究陶瓷膜层微观形貌及组成,采用拉伸法、中性盐雾试验、轴向加载疲劳试验等方法研究附着力、耐蚀性及疲劳性能等。结果表明:陶瓷膜层大致由表层疏松层、中间致密层以及内部过渡层组成,表层疏松多孔,过渡层与基体紧密结合。陶瓷层与基体结合好,附着力大于50MPa;微弧氧化处理后,大幅度提高合金耐腐蚀性能,中性盐雾大于336h;陶瓷膜层使基体疲劳性能降低18%。

Micro-arc oxidation（MAO）process on ZM6 Mg alloy was carried out in a dual electrolyte system of sodium silicate and sodium hydroxide alkalescent solution.The microstructure characteristics of coatings were investigated by scanning electron microscopy（SEM）and X-ray diffraction（XRD）.The performance of adhesion,corrosion resistance and fatigue was evaluated by dynamic stretch training,neutral salt spray test and axial loading fatigue test.The results show that MAO coating consists of three layers,outer layer,medial layer and inner layer.The outer layer is porous and loose,however the inner layer has good bond strength with substrate,which is above 50 MPa.The MAO coating can improve corrosion resistance of substrate significantly.The neutral salt spray test is above 336 h.Compared with the sample without MAO coating,the reduction of fatigue is about 18%.