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

被引：0
作者：
Wei-ping Li
Xi-mei Wang
Li-qun Zhu
Wen Li
机构：
[1] Beihang University,Key Laboratory of Aerospace Materials and Performance (Ministry of Education of China), School of Materials Science and Engineering
来源：
International Journal of Minerals, Metallurgy, and Materials | 2010年 / 17卷
关键词：
magnesium alloys; coatings; aluminium nitrate; corrosion resistance;
D O I：
暂无
中图分类号：
学科分类号：
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.
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页码：641 / 647
页数：6
相关论文
共 39 条
  • [1] Gray J.E.(2002)Protective coatings on magnesium and its alloys—A critical review J. Alloys Compd. 336 88-undefined
  • [2] Luan B.(2005)Effect of RE on the ignition-proof, microstructure and properties of AZ91D magnesium alloy J. Univ. Sci. Technol. Beijing 12 540-undefined
  • [3] Chen Z.H.(2005)Growth characterization of anodic film on AZ91D magnesium alloy in an electrolyte of Na J. Univ. Sci. Technol. Beijing 13 450-undefined
  • [4] Ren X.P.(2007)SiO Appl. Surf. Sci. 253 6922-undefined
  • [5] Zhang Y.(2007) and KF Corros. Sci. 49 4542-undefined
  • [6] Li W.P.(2006)Characterization of rare-earth conversion films formed on the AZ31 magnesium alloy and its relation with corrosion protection J. Electrochem. Soc. 153 B90-undefined
  • [7] Zhu L.Q.(2003)Stannate and permanganate conversion coatings on AZ31 magnesium alloy Surf. Coat. Technol. 172 227-undefined
  • [8] Li Y.L.(2003)Formation of phosphate/permanganate conversion coating on AZ31 magnesium alloy Mater. Chem. Phys. 80 191-undefined
  • [9] Zhao B.(2006)Cerium-based chemical conversion coating on AZ63 magnesium alloy Surf. Coat. Technol. 200 5407-undefined
  • [10] Montemor M.F.(2007)Conversion-coating treatment for magnesium alloys by a permanganate-phosphate solution Scripta Mater. 56 927-undefined
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