Bioactivity Of Magnesium Alloy Research Articles

Influence of current mode on microstructure and corrosion behavior of micro-arc oxidation (MAO) biodegradable Mg-Zn-Ca alloy in Hank's solution

To improve the corrosion resistance of magnesium, the ceramic coatings were prepared on Mg-4.71Zn-0.6Ca alloy by micro-arc oxidation (MAO) with different current modes. The microstructure, thickness, and composition of the coatings were characterized by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS) and X-ray diffraction (XRD). The electrochemical test was used to evaluate the corrosion behaviors of the Mg alloy, and the degradation rate of Mg alloy was investigated by immersion tests in Hank's solution, and the corrosion products were analyzed by EDS, XRD and fourier transform infrared spectrometer (FT-IR). The experimental results showed that the corrosion resistance of Mg-4.71Zn-0.6Ca alloy was significantly improved by MAO treatment, and the MAO Mg alloy prepared under hybrid mode exhibited the better corrosion resistance than other two modes, and the bioactivity of magnesium alloy was also improved. The MAO Mg-4.71Zn-0.6Ca alloy that prepared under hybrid mode had the potential to be served on bone repair and implant materials.

Plasma-Sprayed Hydroxyapatite Coating for Improved Corrosion Resistance and Bioactivity of Magnesium Alloy

In the present study, the corrosion resistance and bioactivity of AZ91HP magnesium alloy were improved by plasma spraying hydroxyapatite (HA) coating. X-ray diffraction measurements indicated that the coating formed amorphous and little β-Ca3 (PO4)2 besides of HA. The corrosion resistance and bioactivity of the coating and magnesium alloy in simulated body fluid were investigated using immersion test. The coating showed lower corrosion rate and better bioactivity than magnesium alloy. The coating significantly improved the hydrophilicity of Mg alloy. The prothrombin time of the coating was 18 s, and the prothrombin time of Mg alloy was 11 s, so the coating had better anticoagulant activity.

Preparation and characterization of hydroxyapatite containing coating on AZ31 magnesium alloy by micro-arc oxidation

Magnesium alloys have received great attention as a new kind of biodegradable metallic implants. However, poor corrosion resistance limited its applications. In order to improve the corrosion resistance and bioactivity of magnesium alloys, hydroxyapatite containing coatings were grown on AZ31 magnesium alloy by microarc oxidation. The thickness, morphologies and component of the coatings were investigated by SEM, XRD and XPS. Further, the corrosion resistance and degradation rate were also investigated. The main crystal phases of the coatings were MgO and hydroxyapatite. The thickness of the coatings increased with increasing the NaOH concentration. The coating showed a porous structure, and volcano top-like pores could be observed when the NaOH concentration was higher than 0.2 mol/L. Compared with the AZ31 substrate, all the coatings showed to significantly improve the corrosion resistance and greatly reduce the degradation rate. Among all, the coated sample formed in 0.2 mol/L NaOH showed the best corrosion resistance and the lowest degradation rate. Furthermore, complete coatings performed higher bonding strength more than 50 MPa, which meets the requirement of an implant biomaterial. This study provides insight into the development of bioactive coatings on magnesium alloys for biomedical applications.