The Effect Of Laser Melting On Corrosion Behaviour And Cell Compatibility Of AZ91D Magnesium Alloys

The good biological properties and mechanical properties of magnesium alloys have attracted much attention,but their application is limited due to the rapid degradation rate of magnesium alloys.At present,there are many surface modification methods to treat magnesium alloys,such as magnetron sputtering,biomimetic mineralization and so on.Among them,laser surface melting is favored because of its advantages of controllable thickness,compact structure and little environmental pollution.Objective: To improve the corrosion resistance and cell compatibility of magnesium alloys by laser surface melting on the magnesium alloy.Methods: The surface of magnesium alloy was fused with gas laser.The structure,composition,surface energy and surface roughness of the magnesium alloy by laser surface melting were tested by using scanning electron microscopy,metallographic microscope,X-ray energy spectrum analyzer,the contact Angle test,X-ray diffraction and 3D profilometer,respectively The corrosion resistance and cell compatibility of the magnesium alloy by laser surface melting were studied by means of dynamic potential polarization curve,hydrogenation experiment,cell adhesion experiment and MTT.Results: After laser surface melting,the thickness of the melting layer reached1300 ?m.Grain refinement in the melting layer,the size of the ?-Mg17Al12 is refined from 61 to 6 ?m;The content of Mg decreased from 89.88% to 70.13%.However,the content of Al increased from 9.23% to 28.08%,and the distribution of Al was even more uniform.Contact Angle from 71.5°(±1.1,N=10)reduce to 53.9°(±1.3,N=10),The surface energy of the melting layer increase;The surface roughness increased from 0.16±0.02 ?m to 2.53±0.03 ?m.Potentiodynamic polarization curves and hydrogen evolution experiment results show that the high corrosion potential(-1154 m V vs.Ag/Ag Cl)and low corrosion current density(8.920×10-5 A/cm2)are displayed by the magnesium by laser surface melting.Compared with the as-received,the corrision potential of magnesium by laser surface melting increased 156 m V,the corrosion current reduced by 10 times.In addition,the hydrogen deposition rate of magnesium alloy is much lower than that of the as-received.Cell adhesion experimentresults show that,the amount of cells on the magnesium surface by laser surface melting is more,and spread out on the material surface.The cells and cells,the cells and material adhered respectively.Cytotoxicity test showed that there was no difference in the cell activity between as-received and the magnesium alloy by laser surface melting after 1,4,7 days,but the rate of cell growth of the as-received and the magnesium by laser surface melting was more than 80%,indicating that the materials are not toxic to cells.Conclusion: The magnesium by laser surface melting can significantly improve its corrosion resistance and cell adhesion,and is not toxic to cells.