ABSTRACT
In this work, the non-aqueous NH4F-EG electrolyte was utilized for plasma electrolytic oxidation (PEO) process on AZ91 alloy to fabricate MgF2-dominated coating at room temperature. Results revealed that the coating had a homogeneous composition and porous microstructure. Compared with the bare AZ91 samples, the coated samples showed a 109 mV nobler corrosion potential and two orders of magnitude lower corrosion current in neutral 3.5 wt% NaCl solution, while a 54 mV nobler corrosion potential and one orders of magnitude lower corrosion current in acidic 3.5 wt% NaCl solution (pH=3). Thus, it’s unveiled a novel possibility to prepare non-oxide coating on Mg alloy by PEO process in non-aqueous electrolyte. And the MgF2 coating provided effective corrosion protection for Mg alloy both in neutral and acid corrosive media.
Acknowledgments
This work was supported by One-Three-Five Strategic Planning of Chinese Academy of Sciences (CAS). The authors are grateful to Mr Guantao Kou and Dr Dongmei Li for the SEM and XRD characterization, respectively.
Disclosure statement
No potential conflict of interest was reported by the author(s).