镁锂合金表面耐蚀微弧氧化膜的研究

Study on Corrosion Resistance Coating Formed on Magnesium-Lithium Alloy by Micro-Arc Oxidation

摘要:

利用微弧氧化技术在镁锂合金的表面成功制备了微弧氧化膜。利用SEM、XRD、XPS、动电位极化和电化学交流阻抗谱对微弧氧化膜结构、相组成以及耐蚀性能进行了研究。SEM观测结果表明，氧化膜层的结构是由疏松层和致密层组成的双层结构，微弧氧化膜表面存在大量直径约2~7 mm的微孔。XRD和XPS分析表明，微弧氧化膜的主要相组成为方镁石氧化镁和无定形磷酸盐化合物。动电位极化曲线以及电化学交流阻抗谱分析表明，微弧氧化处理后镁锂合金的耐蚀性能得到显著提高

Abstract:

Micro-arc oxidation (MAO) coatings have been successfully prepared on Mg-Li alloys by micro-arc oxidation. The structure, phase composition and anti-corrosion behavior of MAO coatings are investigated by SEM, XRD, XPS, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). SEM images indicate the MAO coatings possess two layers “dense” and “loose layer”. Plenty of micropores exist on the surface of MAO coatings. The diameter of micropores ranges from 2 to 7 mm. XRD and XPS analysis reveal that MAO coatings are mainly composed of periclase MgO and amorphous phosphate compounds. Potentiodynamic polarization and electrochemical impedance spectroscopy results show that the corrosion resistance of Mg-Li alloys has been improved obviously after MAO treatment.