The Study On The Biodegradable N-MgO/Mg-Zn-Ca Nanocomposite For Biomedical Applications

Due to their excellent biocompatibility,mechanical and biodegradable properties,magnesium alloy and its composite have become a new generation of biomedical implant materials,and they have broad prospects for clinical application in bone tissue repair,vascular anastomosis nail and vascular stent field.In order to improve the corrosion resistance and mechanical properties of magnesium alloys for biomedical implant applications,novel biodegradable Mg-3Zn-0.2Ca?wt.%?matrix composites,reinforced with various MgO nanoparticle loadings?0.1,0.2,0.3,0.5 wt.%?,were devised and prepared using traditional metallurgical casting with high shear melt conditioning.Then a protective film of Mg?OH?₂ was prepared on the surface of composite.In this paper,the solution treatment process of matrix alloy was studied;the combination between MgO particles and matrix interface,and the specific orientation relationship between two phases were investigated.The microstructure,mechanical properties and corrosion resistance of the specimens were systematically analyzed,and the influence mechanism of MgO nanoparticles on various properties was also explored.The results were as follows:?1?450?-48h was the most suitable solution treatment process.A substantial reduction in the content of the secondary phases was found in the solution treated sample,and the corrosion resistance was improved dramatically.It was found that the as-extruded MZCxs?x=0.1,0.2,0.3,0.5?composites exhibited fine grain structure with uniformly distributed MgO particles.The orientation relationships?ORs?of[2-1-10]_?-Mg//[011]_MgO and?1-11?_MgO².62°from?0002?_?-Mg were observed between the MgO particles and the?-Mg matrix,verifying the excellent interfacial bonding without defects between the phases.?2?The addition of MgO nanoparticles dramatically improved the mechanical properties and corrosion resistance of composites.The UTS and YTS value increased to 300MPa and329.03MPa respectively with 0.5 wt.%of MgO added in the matrix,while the elongation value dropped to 14%.MZC0.2s showed the best corrosion resistance,and its corrosion potential,current density and corrosion rate were-1.659V,16.4?A/cm² and 3.10 mm/y respectively.?3?The most protective Mg?OH?₂ film was obtained by hydrothermal reaction at 160?for 4h,and the maximum thickness reaches 40.54?m.The corrosion resistance of composite with Mg?OH?₂ film was improved a lot.Its corrosion current density decreased by 47.56%,and the corrosion rate reduced to 2.51 mm/y.