Formation mechanism of an aluminium-based chemical conversion coating on AZ91D magnesium alloy

被引：0

作者：

Weiping Li Ximei Wang Liqun Zhu and Wen Li Key Laboratory of Aerospace Materials and Performance Ministry of Education of China School of Materials Science and Engineering Beihang University Beijing China ^{[100083
]}

机构：

来源：

International Journal of Minerals Metallurgy and Materials | 2010年 / 17卷 / 05期

关键词：

magnesium alloys; coatings; aluminium nitrate; corrosion resistance;

D O I：

暂无

中图分类号：

TG146.22 [];

学科分类号：

080502 ;

摘要：

An environmentally clean aluminium-based conversion coating on AZ91D magnesium alloy was studied in aluminium nitrate solutions. The morphology, composition, structure, and formation mechanism of the coating were investigated in detail using scanning electron microscopy/energy dispersion spectrometry, X-ray diffraction, transmission electron microscopy, and electrochemical corrosion tests. The results show that the conversion coating is composed of magnesium, aluminium, and oxygen, and shows an amorphous structure. In the initial stage of coating formation, the grain-like nucleus is composed of Al10O15·xH2O, (Al2O3)5.333, Al2O3, AlO(OH), MgAl2O4, (Mg0.88Al0.12)(Al0.94Mg0.06)2O4, and (Mg0.68Al0.32)(Al0.84Mg0.16)2O4. The conversion coating formed in the 0.01 mol/L aluminium nitrate solution for 15 min can improve the corrosion resistance of the magnesium alloy greatly. The discussion reveals that the possible formation mechanism for the aluminium-based conversion coating is the reduction reaction on micro-cathodic sites due to the electrochemically heterogeneous magnesium alloy substrate.

引用

页码：641 / 647

页数：7

共 8 条

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