The electrochemical behavior & lifetime of a hot-dip 5-wt% Al-Zn coating in chloride environments

Batch-type hot-dip zinc and 5-wt% Al-Zn coatings were investigated in the p resent work for the comparison of their corrosion resistance, electrochemic al behavior and microstructures, The 5-wt% AI-Zn coatings possess a promine nt electrochemical passivation behavior. Intermetallics formed mainly betwe en iron, aluminum and zinc adhering to the substrate were identified with e nergy-dispersive X-ray analysis and believed to be responsible for the pass ivation phenomena as observed in the electrochemical polarization, The 5-wt % AI-Zn coatings exhibited a much better corrosion resistance than the conv entional hot-dip galvanized steels under salt spray testing, Although the c orrosion potentials of both coatings increased toward the noble potential a s the immersion time increases, 5-wt% Al-Zn coatings mere always nobler tha n hot-dip zinc coatings.