Influence of Mg substrate on the formation mechanism and corrosion resistance of LDH films

Layered double hydroxides (LDH) layer has been synthesized on various Mg substrates (pure Mg, Mg-Li and AZ91 alloy) under atmospheric pressure. Presence of alloying elements resulted in formation of a new compo-sition and accelerated film growth rate. Li promoted homogeneous growth of LDH film, while the cathodic in-termetallics in AZ91 Mg resulted in heterogeneous growth and formation of a porous LDH film, leading to deteriorated corrosion resistance. The dense Mg-Li LDH layer demonstrated high impedance value (4030 omega & sdot;cm2) after 240 h electrochemical impedance spectroscopy (EIS) test, which was much higher than that of the substrate (146 omega & sdot;cm2).