Deposition of microarc oxidation–polycaprolactone duplex coating to improve the corrosion resistance of magnesium for biodegradable implants

The present study addresses the deposition of a duplex coating by microarc oxidation (MAO) treatment and polycaprolactone (PCL) coating to improve the corrosion resistance of Mg. A uniform PCL coating layer is formed by dip coating method on MAO treated Mg, and the corrosion resistance of MAO–PCL duplex coated Mg is evaluated by potentiodynamic polarization study and immersion test. The results reveal that the porous nature of MAO treated Mg fails to offer a better corrosion resistance in Hanks' balanced salt solution (HBSS). However, deposition of PCL coating (using 4 and 7wt.% PCL) over MAO treated Mg significantly increased the corrosion resistance of Mg in HBSS for 7days. The MAO–PCL duplex coating can be a good alternative method of protecting Mg from rapid corrosion for biodegradable implant applications. •Polycaprolactone (PCL) is uniformly coated on microarc oxidation (MAO) treated Mg.•The PCL coating helps to seal the pores of the MAO treated Mg.•MAO–PCL duplex coating significantly improved the corrosion resistance of Mg.