Magnesium (Mg) alloys have been received much consideration
in the automobile, aircraft and aerospace industries due to their low
density, high specific strength and stiffness, excellent castability
and machinability. In general, the majority of Mg-alloy components
are presently manufactured by die-casting method. Conversely,
high strength Mg alloys manufactured from strip casting method
generally offer higher strength and better ductility over conven-
tional casting processes. Despite their desirable properties, the low
corrosion resistance of Mg alloys continues to be an issue which further restricted their large-scale applications. There are many
coating technologies existing for corrosion protection of Mg alloys,
such as anodizing [1], chemical conversion [2], electroplating [3],
thermal spraying [4], and electrochemical deposition [5]. However,
with certain limitations, they are not adequate for use in cruel
environment. Hence proper surface treatment is required to
enhance the corrosion protection performance of Mg alloys.
In recent years, Plasma Electrolytic Oxidation (PEO) process has
been proven as one of the most cost-effective and environmentally
ecofriendly technique for the deposition of ceramic coating over
materials [6e8]. This method is distinguished by the possibility to
achieve relatively thick, hard, well adherent ceramic coatings with
enhanced wear and corrosion performance. This unique combina-
tion of characteristics makes PEO an ideal option for the deposition
of an effective and stable barrier coating on Mg alloys. It is well