Corrosion Resistance And Cytocompatibility Of Carbon Ion Implanted AZ31 Magnesium Alloy

Except its biodegradable,magnesium and its alloys are provided with elastic modulus and density similar to bone.Then,it also have excellent biocompatibility.It is likely to be a kind of ideal temporary implantation.Magnesium element storage on the earth is the eighth in all elements.So,it have attracted much more attention in biomedicine.However,magnesium alloys have very high corrosion rates in physiological environments,hydrogen gas assembled during corrosion results the loss of mechanical integrity long before the expected service life and a rapid increase in the p H value,which have limited their application in the biomedicine.Plasma immersion ion implantation(PⅢ)is one of a surface modified methods.It has shown rapidly in modifying the physicochemical characteristics of metal,ceramics,polymeric materials and so on.Some elements have been proposed to improve the rapidly degradation on magnesium and its alloys via PⅢ.Objective: Carbon is incorporated into AZ31 magnesium alloy surface via carbon plasma immersion ion-implantation method to study the corrosion behavior and cytocompatibility.Methods: Firstly,before ion implantation,the samples were finely ground down to 2000 grit silicon carbide paper,then mirror polished by 0.5 μm alumina powder.In this study,accelerated voltage is 25 kV.Density of carbon is 1×1018ions/cm2、1.5×1018ions/cm2 and 2×1018ions/cm2.The surface morphology,chemical properties were evaluated by field-emission scanning electron microscopy(SEM),and energy dispersive X-ray spectroscopy(EDS).According to glow discharge optical emission spectroscopy(GDOES)compositional depth profiles,carbon concentration is similar to Gaussian distribution.Contact angle was displayed by Surface tensiometer.Raman scattering spectra reveal the pattern of carbon layer on the surface of AZ31 magnesium alloy.The chemical states of some typical elements of the modified layer were detected by X-ray photoelectron spectroscopy(XPS).Electrochemical studies and hydrogen evolution test detected the improvement of corrosion resistance of carbon ion implantation AZ31 magnesium alloy.Cytocompatibility is demonstrated by MTT.Results: After C-PⅢ AZ31,Incomputable small carbon nanoparticles are observed forming on the surface of AZ31.The corrosion potential of the C-2 increase about 250 mV.Its Icorr value(2.432 × 10-6A/cm2)was the lowest.The accumulated H2 evolution volume of C-2 was about 7.98 ml,being the least of all magnesium alloy samples.Mouse MC3T3-E1 were used to display viability of AZ31 and C-PⅢ AZ31.Viability of all of C-PⅢ group are higher than 80%(P<0.05).Conclusions: C-PⅢ could effectively improve the corrosion resistance and cytocompatibility.The results of this work demonstrated the feasibility of applying biomimetic C-PⅢ AZ31 magnesium alloy for corrosion protection,which providing a basis for clinical applications of biodegradable material.