Influence of alloyed magnesium on the microstructure and long-term corrosion behavior of hot-dip Al–Zn–Si coating in NaCl solution

• Published in: Corrosion science Vol. 104; pp. 217 - 226
• Main Authors: Liu, Wei, Li, Mou-Cheng, Luo, Qun, Fan, Hong-Qiang, Zhang, Jie-Yu, Lu, Hu-Sheng, Chou, Kuo-Chih, Wang, Xun-Li, Li, Qian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2016
• Subjects: A. Magnesium; A. Metal coatings; B. EIS; B. Weight loss; A. Magnesium; A. Metal coatings; B. EIS; B. Weight loss
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2015.12.014

[Display omitted] •Equilateral triangle Mg2Si phases appear on the surface of Al–Zn–Si–xMg coatings.•Mg-rich phase can obviously improve the corrosion resistance of Al–Zn–Si–xMg coatings.•Zn–Al LDH more easily precipitates on the Al–Zn–Si–xMg coatings with Mg2+.•Mg2Si has better anti-corrosion effects than MgZn2.•De-alloying stage of Mg2Si contributes to prolong the cathodic protection effect. The effects of alloyed magnesium on the corrosion behavior of hot-dip Al–Zn–Si–xMg (x=0, 1.25, 3 and 4wt.%) coatings were investigated by analysis of the phase composition, long-term immersion test and electrochemical measurements. Mg2Si phase appeared in the Al–Zn–Si–1.25Mg and Al–Zn–Si–3Mg coatings but only MgZn2 phase existed on the surface of Al–Zn–Si–4Mg coating. The alloyed magnesium improves the corrosion resistance of the Mg-containing coatings and the Al–Zn–Si–3Mg coating shows the highest protective properties in the investigation.