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采用电压-时间曲线、全浸腐蚀实验、极化曲线法、X射线衍射法(XRD)、扫描电镜(SEM)、能量色散谱仪(EDS)和X射线光电子能谱法(XPS)等方法研究了AZ91D镁合金在含不同浓度硅酸钠的阳极化溶液中的阳极氧化行为和膜层的成分、结构.结果表明:在本文给定工艺中,AZ91D镁合金的阳极化过程可分为三个阶段:电火花出现之前的致密层生成阶段,少量小电火花出现的多孔层生成阶段,出现较大电火花的多孔膜层稳定生长阶段.阳极氧化过程中,随着阳极氧化溶液Na2S iO3浓度的升高,出现电火花的时间缩短,出现电火花时的电压值降低;阳极化膜的颗粒度变大甚至膜层出现裂纹,膜层厚度基本不变.阳极化膜层中主要含有Mg2+、O2-、S i4+和B3+,主要相结构为MgO、MgS iO3和Mg3B2O6.硅酸钠浓度对阳极化膜的耐蚀性影响较大,当硅酸钠浓度为120g/L时,膜层耐蚀性能最好.
Voltage-time curves, immersion corrosion tests, polarization curves, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) The anodic oxidation behavior and composition and structure of AZ91D magnesium alloy in the anodizing solution containing different concentrations of sodium silicate were studied.The results show that the anodizing process of AZ91D magnesium alloy can be divided into three Stage: During the formation phase of the dense layer before the EDM, a small amount of EDM appeared during the formation phase of the porous layer, and the larger EDM porous layer appeared during the stable growth stage.During the anodization, with the concentration of Na2S iO3 The voltage of EDM decreased and the particle size of the anodized film became larger and even the cracks appeared in the film, the thickness of the film remained almost unchanged.The anodized film mainly contained Mg2 +, O2 -, S i4 + and B3 +, the main phase structure is MgO, MgS iO3 and Mg3B2O6.The concentration of sodium silicate has a great influence on the corrosion resistance of the anodized film. When the concentration of sodium silicate is 120g / L, the corrosion resistance of the film the best.