Abstract
Magnesium and its alloys have been used in many industries, but they are reactive and require protection against aggressive environments. In this study, a compact and relatively pore-free oxide coating was formed on AZ91D magnesium alloy to improve its corrosion resistance by means of the microarc oxidation (MAO) process via the addition of CeCl3 as an additive into the MAO electrolyte. Morphologies and compositions of the coatings were studied with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. It was found that with the addition of CeCl3 into the MAO electrolyte, the obtained coating showed more uniform morphology compared with the coating produced in the CeCl3 free electrolyte. EDS analysis confirmed the presence of cerium in the coating formed in the electrolyte with CeCl3. Polarization tests results showed that the corrosion current density of the coating formed in the CeCl3 containing electrolyte was less than that of the coating formed in the electrolyte without CeCl3. Furthermore, electrochemical impedance spectroscopy (EIS) tests indicated that the coating formed in the electrolyte with the addition of CeCl3 improved the corrosion resistance of the substrate significantly.
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Ghasemi, A, Raja, VS, Blawert, C, Dietzel, W, Kainer, KU, “Study of the Structure and Corrosion Behavior of PEO Coatings on AM50 Magnesium Alloy by Electrochemical Impedance Spectroscopy.” Surf. Coat. Technol., 202 3513–3518 (2008)
Bala Srinivasan, P, Liang, J, Blawert, C, Stormer, M, Dietzet, W, “Effect of Current Density on the Microstructure and Corrosion Behaviour of Plasma Electrolytic Oxidation Treated AM50 Magnesium Alloy.” Appl. Surf. Sci., 255 4212–4218 (2009)
Duan, H, Du, K, Yan, C, Wang, F, “Electrochemical Corrosion Behavior of Composite Coatings of Sealed MAO Film on Magnesium Alloy AZ91D.” Electrochim. Acta, 51 2898–2908 (2006)
Liang, J, Hu, L, Hao, J, “Preparation and Characterization of Oxide Films Containing Crystalline TiO2 on Magnesium Alloy by Plasma Electrolytic Oxidation.” Electrochim. Acta, 52 4836–4840 (2007)
Bai, A, Chen, Z, “Effect of Electrolyte Additives on Anti-Corrosion Ability of Micro-Arc Oxide Coatings Formed on Magnesium Alloy AZ91D.” Surf. Coat. Technol., 203 1956–1963 (2009)
Bala Srinivasan, P, Blawert, C, Dietzel, W, Kainer, KU, “Stress Corrosion Cracking Behaviour of a Surface-Modified Magnesium Alloy.” Scripta Mater., 59 43–46 (2008)
Barchiche, CE, Rocca, E, Hazan, J, “Corrosion Behaviour of Sn-Containing Oxide Layer on AZ91D Alloy Formed by Plasma Electrolytic Oxidation.” Surf. Coat. Technol., 202 4145–4152 (2008)
Hsiao, HY, Tsai, WT, “Characterization of Anodic Films Formed on AZ91D Magnesium Alloy.” Surf. Coat. Technol., 190 299–308 (2005)
Song, G, Atrens, A, Dargusch, M, “Influence of Microstructure on the Corrosion of Diecast AZ91D.” Corros. Sci., 41 249–273 (1998)
Bala Srinivasan, P, Liang, J, Blawert, C, Stormer, M, Dietzel, W, “A Preliminary Study of Calcium Containing Plasma Electrolytic Oxidation Coatings on AM50 Magnesium Alloy.” J. Mater. Sci., 45 1406–1410 (2010)
Laleh, M, Sabour Rouhaghdam, A, Shahrabi, T, Shanghi, A, “Effect of Alumina Sol Addition to Micro-Arc Oxidation Electrolyte on the Properties of MAO Coatings Formed on Magnesium Alloy AZ91D.” J. Alloys Compd., 496 548–552 (2010)
Yerokhin, AL, Nie, X, Leyland, A, Matthews, A, Dowey, SJ, “Plasma Electrolysis for Surface Engineering.” Surf. Coat. Technol., 122 73–93 (1999)
Shengxue, Y, Qiaoyan, L, Jing, H, Zhanwi, Z, Qianyun, Z, “Preparation and Performance of Rare Earths Chemical Conversion Film on Magnesium Alloy.” J. Rare Earths, 24 397–400 (2006)
Lingjie, L, Jinglei, L, Shenghai, Y, Yujing, T, Qiquan, J, Fusheng, P, “Formation and Characterization of Cerium Conversion Coatings on Magnesium Alloy.” J. Rare Earths, 26 383–387 (2008)
Wang, C, Zhu, S, Jiang, F, Wang, F, “Cerium Conversion Coatings for AZ91D Magnesium Alloy in Ethanol Solution and Its Corrosion Resistance.” Corros. Sci., 51 2916–2923 (2009)
Ikonopisov, S, “Theory of Electrical Breakdown During Formation of Barrier Anodic Film.” Electrochim. Acta, 22 1077–1082 (1977)
Bestetti, M, Barlassina, F, Da Forno, A, Cavallotti, PL, “Effect of Electrolyte Composition on Micro-Arc Anodization of AM60B Magnesium Alloy.” Metall. Sci. Technol., 26 9–15 (2008)
Shi, P, Ng, WF, Wong, MH, Cheng, FT, “Improvement of Corrosion Resistance of Pure Magnesium in Hanks’ Solution by Microarc Oxidation with Sol–Gel TiO2 Sealing.” J. Alloys Compd., 469 286–292 (2009)
Ahn, SH, Lee, JH, Kim, HG, Kim, JG, “A Study on the Quantitative Determination of Through-Coating Porosity in PVD-Grown Coatings.” Appl. Surf. Sci., 233 105–114 (2004)
Liu, C, Bi, Q, Leyland, A, Matthews, A, “An Electrochemical Impedance Spectroscopy Study of the Corrosion Behaviour of PVD Coated Steels in 0.5 N NaCl Aqueous Solution: Part II. EIS Interpretation of Corrosion Behaviour.” Corros. Sci., 45 1257–1273 (2003)
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Laleh, M., Kargar, F. & Sabour Rouhaghdam, A. Formation of a compact oxide layer on AZ91D magnesium alloy by microarc oxidation via addition of cerium chloride into the MAO electrolyte. J Coat Technol Res 8, 765–771 (2011). https://doi.org/10.1007/s11998-011-9357-7
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DOI: https://doi.org/10.1007/s11998-011-9357-7