Controlling in vitro corrosion rate of pure Mg with rough surface texture via biomimetic coating systems

Abstract

Introducing coating layers on magnesium substrates for added corrosion protection has been one of the most popular methods to improve the relatively poor corrosion resistance of Mg biomaterials. Investigations on coating systems for Mg biomaterials to date have predominantly focused on smooth, polished surface topographies. Given that the corrosion resistance of biodegradable Mg increases with increasing surface roughness, the potential effectiveness of currently adopted coating methods could also be affected by changes in Mg surface topography. In this study, a biomimetic calcium phosphate (CaP) coating technique was employed to study the corrosion resistance of cast, pure Mg samples with high surface roughness of R _a = 9·12 μm. The effectiveness of the coating technique on rough samples was tested in vitro and compared with that of the raw polished pure Mg samples. It was found that while the biomimetic coating technique provided excellent corrosion protection to the smooth polished samples, the improvement in corrosion behaviour of rough cast samples was not as significant. With the findings in this study, it is suggested that future studies on Mg coatings should be performed on rough as well as smooth surfaces for a complete evaluation on the effectiveness of the coating system.