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

Abstract

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.