NaF assisted preparation and the improved corrosion resistance of high content ZnO doped plasma electrolytic oxidation coating on AZ31B alloy

•Fluoride ion salt can regulate the discharge behavior of the PEO on AZ31B alloy in the ZnO contented electrolyte by forming MgF2 .•The interval MgF2 decreases the breakdown voltage and discharge voltage resulting in a hypoactive ablation.•The high-content ZnO doped PEO coating shows excellent electrochemical corrosion resistance and salt spraying lifetime of 2000 h.•The ZnO doping is benefited to produce continuous Zn(OH)2 protective layer and restrict the permeation of corrosive medium.