Sandwiched polydopamine (PDA) layer for titanium dioxide (TiO2) coating on magnesium to enhance corrosion protection.

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]