正向截止电压对ZM5镁合金微弧氧化膜层厚度及耐蚀性能的影响  

Effect of Forward Cut-off Voltage on Thickness and Corrosion Resistance of Micro-arc Oxidation Film on Surface of ZM5 Magnesium Alloy

作　　者：刘元海 殷强 孟娇 LIU Yuanhai;YIN Qiang;MENG Jiao(Aviation Key Laboratory of Science and Technology on Structural Corrosion Prevention and Control,China Special Vehicle Research Institute,Hubei Jingmen 448035,China;School of Materials Science and Engineering,Inner Mongolia University of Technology,Hohhot 010051,China)

机构地区：[1]中国特种飞行器研究所结构腐蚀与控制航空科技重点实验室,湖北荆门448035 [2]内蒙古工业大学材料科学与工程学院,呼和浩特010051

出　　处：《装备环境工程》2025年第4期125-134,共10页Equipment Environmental Engineering

摘　　要：目的研究采用双极性叠加脉冲工艺在ZM5镁合金表面制备微弧氧化膜时,正向截止电压对膜层厚度及耐蚀性能的影响规律。方法采用扫描电子显微镜(SEM)和能谱仪(EDS)对微弧氧化膜层的形貌和元素分布进行观察分析,通过电子探针(EPMA)对截面元素进行面扫描,明确不同截止电压下微弧氧化膜层厚度的变化及截面上的元素分布特点。结果及结论随着正向截止电压由380 V逐步提升至400、420、440 V,ZM5镁合金表面微弧氧化生成的膜层厚度分别达到10、20、30、40μm。膜层厚度的增加没有明显影响到Si、Na、K、O、F、Mg等元素在表面上的分布,厚膜层截面上O元素富集在膜层外面,F元素富集在膜层内部,这种分布模式与微弧氧化过程中离子迁移和化学反应机制紧密相关。膜层的耐蚀性能随膜层厚度增加而增强,这归因于更厚的膜层为基体金属提供了有效的物理屏障,阻碍了物理性介质与基体的直接接触。其电化学阻抗值的提升并未呈现严格的线性关系,这主要由于膜层厚度达到一定程度时,内部应力的累积及扩散速率的限制导致膜层中出现裂纹、疏松等微结构缺陷,这些缺陷作为腐蚀介质的快速通道,使膜层的整体防护效能降低。The work aims to study the effect of forward cut-off voltage on the thickness and corrosion resistance of micro-arc oxidation(MAO)film prepared on the surface of ZM5 magnesium alloy by bipolar superposition pulse technology.The surface morphology and element distribution of the MAO film were observed and analyzed by scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The cross-sectional area was mapped by electron probe micro-analysis(EPMA)to determine the changes in the thickness of the MAO film and the distribution characteristics of various elements under different cut-off voltages.The forward cut-off voltage increased from 380 V to 400 V,420V and 440V and the thickness of MAO film on the surface of ZM5 magnesium alloys reached 10μm,20μm,30μm and 40μm,respectively.With the increase of film thickness,the distribution of Si,Na,K,O,F,Mg on the surface had no obvious difference.On the cross section of the thicker film,element O was enriched outside the film,and element F was enriched inside,reflecting ion migration and chemical reaction mechanisms inherent to the MAO process.The corrosion resistance of the films increases with the increasing thickness,because the thicker film provides an effective physical barrier against corrosive media.However,the enhancement in electrochemical impedance does not follow a strictly linear relationship with film thickness,likely due to the accumulation of internal stresses and diffusion limitations as the film reaches a critical thickness,leading to microstructural defects such as cracks and porosity,which diminishes the overall protective efficacy of the MAO film.

关 键 词：镁合金 微弧氧化 截止电压 耐蚀性 

分 类 号：TG174[金属学及工艺—金属表面处理]