Preparation and characterization of anodic films on AZ31B Mg alloy formed in the silicate electrolytes with ethylene glycol oligomers as additives

► Anodic films formed on AZ31B Mg alloy in the silicate electrolyte. ► Compact and smooth film obtained by using PEGs as additives in the electrolyte. ► Anti-corrosion and Anti-friction enhanced by adding PEG1000 in the electrolyte. ► The growth rate and amount of the anodic oxides related to the length of PEG chains.