Effect of preparation parameters on the properties of hydroxyapatite containing micro-arc oxidation coating on biodegradable ZK60 magnesium alloy

Recently, micro-arc oxidation (MAO) is intensely studied as a promising surface treatment method for biodegradable magnesium alloys due to the excellent wear resistance and bonding strength of the MAO coating. In order to improve the bioactivity of the coating, hydroxyapatite (HA) nano-particles were added in the MAO electrolyte in the present study to prepare HA containing MAO coatings on the biodegradable ZK60 magnesium alloy. The HA concentration in the electrolyte, the preparation voltage and oxidation time were adjusted to prepare coatings with different morphologies, composition and properties. It was found that the coating was greatly influenced by these three parameters. The immersion test demonstrated that the HA containing MAO coating owned increased bioactivity and long-term protective ability compared with the base coating. A HA containing coating with good combination of corrosion resistance and phase composition could be obtained by properly selecting the above parameters.