Research has clarified the properties required for PEO coatings
that resist corrosion on Mg alloys for use in industrial applications.
It seems that the most favorable approach to produce PEO coatings
is to reduce the defects and increase the content of chemically
stable compounds through selecting appropriate electrolytes and
processing parameters [20]. It is expected that mixture of more
than one electrolyte will enhance the microstructure and performance
of PEO coatings. However, a systematic research of the effect
of dual or multiple electrolytes has not been well documented in
literature. In the current work, silicate (Na2SiO4) and phosphate
(Na3 (PO4)2) were taken into account to form a dual PEO coating
with additives of KOH, and KF to fabricate compact, smooth and
corrosion-resistant coatings on AZ31 Mg alloy under constant
current mode.