The corrosion behavior of Zn coatings on Al-3103 alloy

Zinc films, 4 μm thick, were deposited on an Al–Mn alloy (Al-3103) plate using an ion beam-assisted deposition method. The corrosion behavior of the zinc coating samples was investigated in 0.1 M NaCl solutions in the presence and absence of bicarbonate/carbonate buffers. In the unbuffered NaCl solutions, both the Al-3103 and Zn/Al-3103 samples showed active dissolution, but Zn/Al-3103 had more negative corrosion potential and bigger corrosion current than the Al-3103 samples. In the buffered NaCl solutions, the Al-3103 samples showed passivation, while Zn/Al-3103 had a noble corrosion potential compared to the former. The surface compositions of samples, before and after zinc deposition, were checked using Rutherford backscattering spectroscopy. The surface chemical states for samples after corrosion were analyzed by means of X-ray photoelectron spectroscopy. The corrosion products were mainly zinc oxides, zinc hydroxides and aluminum oxides.