(华南理工大学 机械工程学院,广州 510640)
摘 要: 采用SEM、TEM、EDX、XRD、AUTOLAB电化学工作站分析比较两种电解质(硅酸盐体系和有机胺体系)直流微弧氧化处理AZ91D合金表面涂层的成分、组织结构和涂层的动电位极化曲线。虽然两种电解质体系涂层元素成分和组成相相同,均为金属相、MgO相和Mg2SiO3相,但有机胺电解质体系的涂层中非金属相(MgO、Mg2SiO4)相对含量高于硅酸盐处理体系,有机胺体系获得的涂层表面均匀致密性也优于硅酸盐体系。有机胺体系获得的涂层在3.5% NaCl中性介质中的腐蚀电流密度、腐蚀电压分别为0.29 mA/cm2 和522 mV,与硅酸盐体系处理涂层相比,前者的抗腐蚀能力有很大幅度的提高。
关键字: 镁合金;微弧氧化;电解质;有机胺;腐蚀
(College of Mechanical Engineering, South China University of Technology, Guangzhou 510640, China)
Abstract:Abstract: By means of SEM, TEM, EDX, XRD and AUTOLAB, the composition, constituent phase, microstructure and corrosion resistance of two micro-arc coatings were investigated, which were treated in two electrolytes: organic amine system and silicate solution. The results show that the constituent phases in coatings from two electrolyte are the same, i.e., α/β-Mg, MgO and Mg2SiO4; the relative fraction of ceramic phases in the coating from organic amine is higher, and the coating surface morphology looks finer and denser than those from silicate solution. According to the potential-dynamic polarization curves in 3.5% NaCl solution, the corrosion current density and corrosion voltage from organic amine treated coating are 0.29 mA/cm2 and 522 mV respectively. The corrosion resistance of organic amine treated coating is improved significantly.
Key words: magnesium alloy; micro-arc oxidation; electrolyte; organic amine; corrosion