Corrosion protection of folic acid and lauric acid modified films prepared by anodic oxidation on WE43 magnesium alloys

The corrosion protection of folic acid (FA) and lauric acid (LA) modified films prepared by anodic oxidation on WE43 magnesium alloys was particularly evaluated by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), static contact angle (CA) and electrochemical tests. The combined results of SEM and EPMA showed that both FA and LA penetrated into the cavities and cracks to repair the defects of the anodic films. The polarization resistance of the FA-modified films increased by 1.56 × 105 Ω cm2 and the LA-fmodified films showed the largest value (6.36 × 106 Ω cm2). They improved by two and three orders of magnitude compared with the substrate, which objectively revealed the excellent corrosion resistance capacity of the modified films on measurement results level. The CA results indicated that the obtained anodic films modified by LA were hydrophobic. Furthermore, the process of the organic modification sealing and the corrosion protection mechanism of the anodic films modified by FA and LA were discussed.