Preparation And Properties Of Micro-arc Oxidation Coating Containing Nano-hydroxyapatite On AZ31 Magnesium Alloy

Magnesium alloys have many advantages,such as mechanical properties similar to those of natural bones,the presence of natural ions with important functional roles in biological systems,and the in vivo degradation by corrosion in vivo electrolysis of the environment.However,the major disadvantage of magnesium alloys in applications is their low corrosion resistance,especially in electrolytic environments.In addition,the degradation of magnesium alloy always leads to hydrogen evolution and alkalization of the solution.Object: In order to improve the corrosion resistance and biological activity of AZ31 magnesium alloy on the surface of AZ31 magnesium alloy;Materials and methods: Two types Micro-arc oxidation films were prepared by using micro-arc oxidation.One electrolyte used sodium hexametaphosphate as the main salt,another electrolyte used sodium hexametaphosphate as the main salt and nano-hydroxyapatite(HA)as the additive to prepare the PEO coating on the surface of AZ31 magnesium alloy.The morphology,structure and composition of the coatings were characterized by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The corrosion resistance of the coating was investigated by electrochemical method and immersion experiment.The cell compatibility was evaluated by cell proliferation and morphological observation;Results :The results showed that the HA in the electrolytic solution enters into the micro-arc oxidation film to obtain the micro-arc oxidation film containing HA.Compared with the HA-free micro-arc oxidation film,the micro-arc oxidation film containing HA is more compact and it also has the sealing phenomenon.Electrochemical method and immersion test showed that the HA-MAO has a better corrosion resistance than the MAO After the 24-hour-long cell culture,the Cell surface adhesion observation of cells cultured 24 hours later,revealed that the HA-MAO surface cell growth status better than the MAO;MTT assay showed that AZ31 magnesium alloy containing HA micro-arc oxidation not only does not has any toxic effects on cells,but also it can promote the proliferation of MC3T3-E1 cells;Conclusion:The addition of nano-HA in the solution of sodium hexametaphosphate can produce HA-containing micro-arc oxidation coating on the surface of AZ31 magnesium alloy,and its corrosion resistance and cell compatibility are much higher than those of HA-free micro-arc oxidation coating.