Oxygen plasma ion implantation of biomedical titanium alloy

Titanium alloys have attracted more attention as biomaterials. Plasma ion implantation is utilized in this paper to improve the bioactivity, wear resistance, and corrosion resistance of Ti6Al4V alloy. As an effective surface-modification technique, plasma ion implantation eliminates the limitation of light of sight compared to conventional beam ion implantation. The plasma is excited by an RF power ranging from 200 to 400 W with sample bias of 20 kV. The results show the improvement in hardness, corrosion resistance, and tribological properties. Longer treatment time or higher RF power leads to a higher wear resistance. The friction coefficient rapidly increases at 500 s with the sample treated with the RF power of 400 W, while it changes abruptly at 1500 s with the sample processed with the RF power of 600 W. After the treatment, the corrosion resistance is considerably improved, which demonstrate that the potential of the samples shift positively while the corrosion current decreases substantially. The corrosion current may decrease by a factor of six compared to that of the control sample. The precipitates containing phosphorous and calcium appear, indicating a better activity while nothing grows on the untreated sample.