Silver Ions Into Stainless Steel, Titanium Nitride Film And Pyrolytic Carbon Antibacterial, Anti-corrosion Research

The antimicrobial test of silver implanted silicon, SS(stainless steel) 317L substrates and the silver implanted TiN coatings on them was performed using Staphylococcus aureus which is gram positive, and Ag⁺-implanted pyrolytic carbon are also tested at same time. The results show that Ag⁺-implanted pyrolytic carbon has better antibacterial properties than that of TiN and SS317. While TiN film with lower dose implantation exhibit poor antibacterial properties. The initial surface of sample play a very important role in killing bacteria, especially in flakelet and samdwich form which can be assigned induce the adhesion of bacterium and destruction of it. The concentration of solution of the samples were only 4 ppb, which did not attain the minimum inhibitory concentration(MIC) . So, the death of the bacterium is most probably caused by the adhesion of it on the surface of the sample, and the antibacterial test proved that the laminated structure of the Ag⁺-implanted pyrolytic carbon have best antimicrobial effect in comparison with the TiN film. Silver can induce the adhesion of hydrogen and oxygen atomic, then -OH and O₂^-comes out, which have strong oxidation ability, It can be assigned to induce the destruction of bacteria. One silver atom can adsorb only one oxygen atom. Sliver doped pyrolytic carbon have the same excellent bactericidal properties with the silver doped active carbon.The corrosion experiments show that the corrosion resistance of the sample E1 and E2(the ion dose was 9×10¹⁶, 5×10¹⁷ ions/cm²) have almost the same i_c (current density), and it is higher than that of the pure TiN thin film up to two orders of magnitude. E4 (the dose was 5 × 10¹⁸ ions/cm )shows about 250 mV in the breakthrough potential of pitting corrosion and its current density increased sharply and distinct from the sample with low silver ion dose and pure TiN thin film. The more silver implanted, the higher current density performed, especially when the dose attained about 10¹⁸ ion/cm in magnitude, and the corrosion resistance decreased accordingly. With increasing ion dose, E_c (corrosion potential)becomes more positive. E_c shifted to anodic direction for Ag⁺- implanted TiN film and SS 317L due to silver ion implantation and the i_c oscillates pronouncedly with large ion implantation dose.So the active corrosion starts.The hardness test of the TiN thin film on SS317 and silicon show that the nanohardness decreases with the ion dose. The hardness value fluctuates around the saturated dose. While Ag+-implanted SS 317 has opposite characteristics, its hardness value increased with the ion dose when the ion dose did not exceeded the saturated dose. However, the hardness becomes smaller with long time implantation.The XRD analysis of Ag+-implanted and non-implanted samples, E0,E2,E4,E0\E2\E4' has shown there were silver peaks in the spectra. Silver lattice structure formed initially. The silver implantation did not change the preference orientation and other crystal plane such as TiN(lll), TiN(220), TiN(200), TiN(lOl), TiN(102), TiN(103), TiN(311). Silver exist in form of (111 ),(200),(220),(311) crystal plane. It can be approved to be pure silver by XPS spectrum.XPS test shows that silver peaks at surface mainly exist in Ag3d5 state. The silver existed as AgO in the surface of E4 , the binding energy were367.83 eV. Silver existed as pure Ag form in the C4 surface and near surface. The TiN film has been sputtered entirely for long time implantation. The fee structure silver and diamond structure silicon interact each other. SiO and SiO2 existed in the surface of C4 which may be due to the process of TiN film deposition.AES profile has been carried out on multi-arc deposited TiN film. N and Ti decreased with the depth of sputerring and the Fe increased at the same time. Which proves that an intermixing layer formed and it makes the strong adhesion between the film and the substrate. The depth of silver ion implantation of C3 and E3 are 48, 36 nanometer respectively, the concentration peak apears at the position of 6 nanometer from the surface of the sample. The gauss distribution of silver has been shifted towards the surface because of the sputtering effect.RBS analysis shows that silver is penetrated into carbon substrate , there is a sharp silver peak at 420 channel . The intensity of silver peak is not propertional to the implantation dose. There is other defect peak at 367 channel, which is probably caused by impurities induced during high dose ion implantation.Scanning electron microscopy (SEM) of the sample surface suggest that there is...