The Study On Surface Modification By Mg/C Ion Implantation Into Titanium

Ion implantation technology can effectively improve the surface properties and biological activity of pure titanium. It will open up a broad prospect to pure titanium to get a better use in clinical practice. Due to the solid integration between implanted ions and the matrix, the variety of candidate ions and the good controllability and repeatability, and non-contamination of this technique itself, MEVVA ion implantation has been extensively studied in recent years.In this paper, carbon and magnesium ions were implanted into the pure titanium respectively using MEVVA. Carbon implantation was carried out at a chosen ion dose of 2.0~6.0×1017 ions/cm2 and the energy of 40 and 60 keV, while magnesium implantation 2.0×1017 ions/cm2 and 90 keV. The effect of ion implantation on the hardness, modulus, wear resistance, friction coefficient and corrosion resistance of pure titanium was examined by different surface property measurements. The surface morphology was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), element content was analyzed by energy dispersive spectrometer (EDS), chemical state of element was determined by X-ray photoelectron spectroscopy (XPS), and the phase structure of the implanted surface was measured by X-ray diffraction (XRD). The precipitation of hydroxyapatite (HA) on Mg-ion-implanted titanium in simulated body fluid (SBF) was studied to assess the improvment of bioactivity of pure titanium.The results showed that after magnesium ion implantation, Mg2TiO5 and MgO/Mg(OH)2 phases have been synthesized on the surface of titanium substrate. The surface hardness and the corrosion resistance of the Mg-ion-implanted samples increased. During immersion in SBF, Mg2+ released from the surface of the samples, which resulted in the charges enrichment on the surface of samples and thus the enrichment of Ca and P in the electrolyte space charge facing the surface. The trend is that the supersaturation level for calcium phosphate precipitation, a condition for the HA nucleation to occur, is preferentially increased in the region adjacent the surface. After immersed in SBF for 168 hours, a dense HA layer was found on the surface of Mg-ion-implanted samples while little HA existed on the un-implanted counterparts. The experimental results demonstrated that Mg-ion-implantation improved the bioactivity of titanium.After carbon ion implantation, a C-ion-implanted layer composing of TiC and dissociative carbon phase has been synthesized on the surface of titanium. The surface hardness and tribological properties of the C-ion-implanted samples increased remarkably. Meanwhile the corrosion resistance of the C-ion-implanted samples was also improved. At the energy of 60 keV and the dose of 2×1017 ions/cm2 the C-ion-implanted samples got the best properties.Magnesium and carbon ion implantation improved the surface properties of titanium obviously. This work provides valuable information for the use of ion implantation on the surface modification of pure titanium.