Advances in coatings on biodegradable magnesium alloys

The clinic applications of bioabsorbable magnesium (Mg) and its alloys have been significantly restricted owing to their poor corrosion resistance. Besides elemental alloying, surface modification and functionality is a major approach to increasing corrosion resistance for magnesium alloys. This article reviews the cutting-edge advances and progress of biodegradable surface coatings upon Mg alloys over the last decades, aims to build up a knowledge framework of surface modification on biodegradable Mg alloys. A considerable number of conversion, deposition, mechanical and functional coatings and their preparation methods are discussed. The emphasis has been placed on the composition of chemical conversion and deposited coatings to overcome the disadvantages of adhesion, corrosion resistance and biocompatibility of a single coating for biomedical materials. The issues have been addressed on the integration of the structural and functional factors of the composite coatings.