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在Na2SiO3和NaOH溶液中,研究了封闭处理对AZ91D镁合金磷酸钡转化膜的影响,采用扫描电镜(SEM)和X射线衍射谱(XRD)研究了封闭前后磷酸钡转化膜的表面形貌及其相组成,采用全浸蚀试验和电化学方法检测了膜层的抗腐蚀性能。结果表明,封闭后的磷酸盐转化膜更加平整、致密。与封闭前的转化膜相比,封闭后的转化膜新增了C、Si元素和一些晶态物质,如SiO2、BaSi4O9、Na2SiO3和MgF2。封闭处理可以明显提高镁合金磷酸钡转化膜的抗腐蚀性能。
In Na2SiO3 and NaOH solution, the effect of blocking treatment on the conversion of barium phosphate into AZ91D magnesium alloy was investigated. The surface morphology of barium phosphate conversion coating was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) Phase composition, the corrosion resistance of the film was tested by the all-etching test and the electrochemical method. The results show that the closed phosphate conversion film is more smooth and dense. Compared with the pre-closed conversion film, the closed conversion film has newly added C, Si elements and some crystalline substances such as SiO2, BaSi4O9, Na2SiO3 and MgF2. Closed treatment can significantly improve the corrosion resistance of magnesium alloy barium phosphate conversion coating.