Stifling magnesium corrosion: Via a novel anodic coating

The use of light-weight magnesium (Mg) alloys as engineering materials has been hampered in part due to their poor corrosion performance. This work aims to address the corrosion issue of Mg by introducing a functional protective coating system consisting of an intermediate active metallic film (anodic with respect to Mg) and an outer passive coating to slow the rate of dissolution of the intermediate active metallic film; which is akin to the protective surface coating system utilised for galvanised steel. If the outer passive coating is damaged or loses its integrity, the active (i.e. anodic) coating is expected to electrochemically sacrifice itself to impose protection upon the underlying Mg substrate. This work represents a novel corrosion protection system for Mg, and is demonstrated herein for a lanthanum based coating system upon commercial Mg-alloy AZ91D.