Biomimetic synthesis and characterization of hydroxyapatite/graphene oxide hybrid coating on Mg alloy with enhanced corrosion resistance

• GO promotes rapid nucleation and crystallization for HA growth.
• Facile to tune the size of HA flakes in hybrid coatings on Mg alloy.
• Homogenous and dense HA/GO crystalline coating with high Ca/P ratio (1.65).
• HA/GO coating significantly improves the corrosion resistance of Mg alloy.

An effective biomimetic method for preparation of hydroxyapatite/graphene oxide (HA/GO) hybrid coating on AZ91 magnesium alloy was firstly proposed. AZ91 Mg alloy was first dip coated by GO, which was further used as matrix substrate for biomimetic mineralization of hydroxyapatite (HA) in modified simulated body fluid (m-SBF). It has been found that GO greatly promotes nucleation and crystallization for rapid HA growth, forming uniform and dense HA/GO hybrid coating comprised by flake-like HA crystals with high Ca/P ratio (1.65). Meanwhile, the as-formed HA/GO bio-coating could dramatically improve the corrosion resistance of Mg alloys. The corrosion current density of treated Mg alloys was decreased by one order of magnitude as compared to untreated one. Furthermore the effects of various experimental parameters toward the growth of the HA/GO coating on Mg alloys were also investigated.