Study Of Surface Modification By Ag/Cu Ion Implantation Into Medical Metallic Materials

In recent years, MEVVA ion implantation has been intensely developed for surface modification of materials. By using the MEVVA ion implantation method, the effects of Ag and Cu ion implantation on the antibacterial properties, microhardness, wear resistance and corrosion behavior of medical metallic materials, stainless steel (317L), pure titanium (TA2) and titanium alloy (Ti6Al7Nb) were investigated.Ion implantation was carried out at an energy of 80keV with Cu implantation doses(0.5×1017, 1×1017, 2×1017, 4×1017 ions/cm2) and Ag implantation doses(0.5×1017, 1×1017, 1.5×1017, 2×1017 ions/cm2).The agar plate method was adopted for evaluation of anti-bacterial activity of the specimens against staphylococcus aureus. Wear rate, friction coefficient, microhardness, corrosion resisting property and ionic release concentration of the modified samples were studied. Microstructure, wear track, composition and concentration profile of elements of implanted layer were analyzed.The results indicate that unimplanted samples have no antibacterial activity. The antibacterial rate against staphylococcus aureus on the surface of three samples are increased with the increasing of copper and silver ions'dose, with an antibacterial efficiency more than 99 % when the Cu and Ag implantation doses approach to 4×1017 ions/cm2 and 1.5×1017 ions/cm2 respectively. The antibacterial mechanism is that Ag+ and Cu2+ ions released from metallic substrates damage staphylococcus aureus. The surface microhardness of both the Cu- and Ag-implantated layers increases by 8.48～46.9 % and 3.88～46.8 %, the corresponding wear rate decreases by 5.79～45.5 % and 12.87～53.29 %. Ti and Ti6Al7Nb exhibit obvious character of abrasive wear and adherent trace. Stainless steel is primarily characterized by abrasive wear. The optimal wear resistance is acquired by three samples which were implanted with a dose of 1×1017 ions/cm2 of Cu and Ag ion implantation. Potentiodynamic test results show that the corrosion resistance of three samples deteriorated appreciably after copper ions implantation, but Ag-implanted three samples maintain their original good corrosion resistance. AES result indicates that Ag reaches its maximum concentration (4.59 %) at a depth of 12 nm and its total depth exceeds 36 nm with a dose of 2×1017 ions/cm2. The high resolution TEM shows three distinct areas near the...