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To address insufficient corrosion control of polymer-coated magnesium, we apply a hydrophobic stearic acid (SA) thin layer underlying the poly (lactic acid) (PLA) and poly (ε-caprolactone) (PCL) coatings on Mg. The SA imbedded polymer-coated Mg showed apparently smaller corrosion current density than the direct-coated counterparts. More importantly, they exhibited manifestly slower and more stable long-term in vitro immersion degradation than the direct polymer-coated Mg up to 21 days. Moreover, the scratch testing disclosed their undercutting corrosion was suppressed evidently. The strengthened corrosion control by the imbedded layer is attributed to its kinetic barrier, hydrophobic nature as well as shielding effect. [ABSTRACT FROM AUTHOR]

The corrosion behavior of Zn was compared with those of Fe and Mg in a long-term course of immersing in phosphate buffered saline (PBS) as biodegradable metal for bio-implants application. The comparison focused on corrosion rate, mode, products and surface characteristics along the immersion degradation up to 21 days. For transient assays, the open circuit potential and corrosion rate placed Zn between Fe and Mg. However, in a long-term course the corrosion rate of Zinc developed faster than Fe and Mg. This was ascribed to its unique localized corrosion and corrosion products changing in contrast to Fe and Mg. [ABSTRACT FROM AUTHOR]

A polydopamine (PDA) layer was sandwiched between a TiO 2 coating and Mg substrate to enhance the corrosion protection. The PDA layer was covalently immobilized on Mg, and the TiO 2 was coated by liquid phase deposition subsequently on it. The hybrid TiO 2 /PDA coated Mg exhibited significantly smaller free corrosion current density as well as a remarkably lower degradation rate in vitro (up to 21 days) in phosphate buffered saline compared to direct TiO 2 coated and untreated Mg. The efficacy is ascribed to the organic PDA layer which suppresses the electric pathway of galvanic corrosion cell and therefore corrosion rate of magnesium. [ABSTRACT FROM AUTHOR]