Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第18卷    第7期    总第112期    2008年7月

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文章编号:1004-0609(2008)07-1211-05
AZ31镁合金钼酸盐转化膜
杨黎晖,李峻青,于 湘,张密林

(哈尔滨工程大学 材料科学与化学工程学院,哈尔滨 150001)

摘 要:

利用钼酸盐溶液在AZ31镁合金表面获得棕黄色的转化膜。用扫描电镜(SEM)和X射线光电子能谱(XPS)对膜层的形貌和组分进行研究,采用动电位极化曲线测试对膜层的耐蚀性进行研究。结果表明:膜的微观形态由球形颗粒构成,膜层厚度约12 μm,对镁合金的覆盖作用良好;转化膜表层中Mo元素主要以MoO3形式存在,在膜的内部钼主要以MoO2和MoO(OH)2存在,并含有部分MoO3;钼酸盐转化膜在阳极极化过程中发生明显的钝化,腐蚀电位正移683 mV,腐蚀电流密度降低2个数量级,明显提高AZ31镁合金的耐蚀性能。同时对镁合金表面钼酸盐转化膜的成膜机理进行初步探讨。

 

关键字: 镁合金;钼酸盐;转化膜;耐蚀性

Molybdate conversion coatings on AZ31 magnesium alloy
YANG Li-hui, LI Jun-qing, YU Xiang, ZHANG Mi-lin

College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China

Abstract:A brown-yellow conversion coating was obtained on the surface of AZ31 magnesium alloy in molybdate solution. The morphology, composition and corrosion resistance of the coating were studied by scanning electron microscopy, X-ray photoelectron spectroscopy, and potentiodynamic polarization analysis, respectively. Potentiodynamic polarization analysis was used to study the corrosion resistance of the coating. The results show that the conversion coatings consist of spherical particles and the thickness of the coating is about 12 μm. The exterior conversion coating consists of MoO3. However, the inner conversion coating mainly consists of MoO2 and MoO(OH)2 as well as a little amount of MoO3. An obvious passivation occurs on the molybdate conversion coating during anodic polarization. The corrosion potential shifts 683 mV positively, and the corrosion current density decreases two orders of magnitude. The corrosion resistance of AZ31 alloy is remarkably improved by the molybdate conversion coating. The mechanism of the coating was discussed briefly.

 

Key words: magnesium alloy; molybdate; conversion coating; corrosion resistance

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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