Characterisation and corrosion behaviour of plasma electrolytic oxidation coatings on high pressure die cast Mg-5Al-0.4Mn-xCe (x=0, 0.5, 1) alloys
Characterisation and corrosion behaviour of plasma electrolytic oxidation coatings on high pressure die cast Mg-5Al-0.4Mn-xCe (x=0, 0.5, 1) alloys
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DOI：
10.1016/j.surfcoat.2014.12.057
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发表时间：
2015-05
影响因子：
5.4
通讯作者：
F. Muhaffel;F. Mert;H. Cimenoglu;D. Höche;M. Zheludkevich;C. Blawert
中科院分区：
文献类型：
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作者：
F. Muhaffel;F. Mert;H. Cimenoglu;D. Höche;M. Zheludkevich;C. Blawert
在本研究中，微量铈（Ce）添加（高达1重量%）的影响，对AM50镁合金进行等离子体电解氧化（PEO）处理，并研究了PEO膜层的耐蚀性能。因此，将基于硅酸盐的PEO涂层沉积在含有0、0.5和1重量%的聚氧化乙烯的AM 50上。Ce在相同的工艺条件下。采用扫描电子显微镜（SEM）、X射线能谱仪（EDS）和X射线衍射仪（XRD）对涂层的表面形貌、横截面微观结构、相组成和化学组成进行了分析。通过盐雾试验和电化学腐蚀试验对涂层的腐蚀行为进行了评价，结果表明：铈的加入降低了涂层的生长速度，但使涂层的厚度变得更加均匀。然而，相组成和涂层形态几乎没有影响，但腐蚀性能显示出很大的差异，这表明多孔PEO涂层必须被视为一个系统的涂层和基体。一个更均匀的腐蚀基板，如铈合金AM50提供了更好的保护与PEO涂层组合比纯AM50。观察到大面积涂层的剥落是由于在界面处形成的腐蚀产物引起的体积增加。这种严重的局部腐蚀在界面处引起的涂层的分层可以通过铈的添加来抑制。
In the present study, the influence of minor cerium (Ce) additions (up to 1 wt.%) to AM50 magnesium alloy on the plasma electrolytic oxidation (PEO) process and the corrosion performance of the PEO coatings were studied. Therefore, a silicate-based PEO coating was deposited on AM50 containing 0, 0.5 and 1 wt.% Ce under the same processing conditions. The resulting surface morphology, cross-sectional microstructure, phase and chemical compositions of the coatings were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analyses (XRD). The corrosion behaviour of the coatings was evaluated by salt spray and electrochemical corrosion tests.The results show that the growth rate of the coating is reduced, but the thickness is becoming more uniform if cerium is added to AM50 alloy. However, the phase composition and coating morphology are hardly influenced, but the corrosion properties reveal large differences suggesting that the porous PEO coatings have to be considered as a system of coating and substrate. A more uniform corroding substrate such as the cerium alloyed AM50 provides much better protection in combination with a PEO coating than the pure AM50. Flaking-off of large coating areas was observed due to the volume increase caused by corrosion products forming in the interface. Such a severe localised corrosion in the interface causing delamination of the coating can be suppressed by cerium addition.